Application wide connection pooling
Just a quick question about connection pooling. How would one go about using application-side connection pooling? For example, I have multiple users logged into my application, all wanting to access the same database (with different username/password credentials). Is this possible? And if so, could someone provide a (brief) code snippet?
Thanks in advance :)
Ben
Thank you for your replies. I understand everything that you have said, but I think that I will elaborate my question further just to make sure that I have everything the right way around in my head.
My application defines a class called Product. This class represents a particular database schema/product. Within the Product class is the member variable;
private transient ConnectionPoolDataSource connectionPool = null;
When the product is constructed a platform-specific pooled datasource is created (either Oracle or MS SQL Server).
com.microsoft.jdbcx.sqlserver.SQLServerDataSource ds = new com.microsoft.jdbcx.sqlserver.SQLServerDataSource();
or
oracle.jdbc.pool.OracleConnectionPoolDataSource ds = new oracle.jdbc.pool.OracleConnectionPoolDataSource();
which is assigned to the aforementioned member variable.
I also have a class called UserSpace which represents a user's work area. Multiple users can access the same product concurrently, and this is why I want to use connection pooling.
A user will do a lot of work "in situ". What I mean by this is that the user will take some time to construct a SQL query, and while they do so their work area is updated with relevant information. When they have fully specified the query that they want to execute I want to be able to grab a connection from the relevant product's connection pool, execute the query, and then hand the connecton back (so that it can be used by someone else).
To me it seems that this should be possible. Indeed I note that there is a method in the ConnectionPoolDataSource class called "getPooledConnection(String username, String password)". This suggests to me that username and password details can be set after the pool is created and that different connections in the pool can have differing user/password details and hence different access priviledges.
Is this correct?
Ben
Similar Messages
-
KIMYONG : Applications Database Connection Pool 관련 parameter 설명
Purpose
JVM 이 과도한 CPU / Memory를 사용하게 되어 Application Performance에 영향을 미칠때가 있으며 이럴경우 Connection Pool 관련하여 Parameter Tunning을 해야 할때가 있습니다. 이때 사용되는 Parameter들의 의미를 설명하고자 합니다.
The Applications Database Connection Pool is a pool of JDBC database connections that are shared among java applications. Applications obtain connections from the pool by using the getJDBCConnection(...) methods of AppsContext.
Essentially, each AppsContext has a single database connection associated with it at all times.
The AOL/J layer internally borrows and returns this connection to the pool as needed to maintain connection reference that is properly initialized for the current Java tier AOL security context and NLS state.
FND_MAX_JDBC_CONNECTIONS
============================
The maximum pool size is the maximum allowed sum of the number of available connections and thenumber of locked connections. If the pool reaches the maximum size and all connections are locked, new clients will not be able to borrow a connection until one of the current clients has returned one. The default setting for this parameter is essentially unlimited (about 2 billion).
FND_JDBC_BUFFER_MIN
======================
The buffer minimum is the minimum number of connections that the pool should try to maintain in the available list. When the buffer size falls below the buffer minimum, the pool maintenance thread will be notified to create new connections. When notified, the thread will immediately attempt to create the number of connections to fill the difference. New connections will not be created if the pool is already at its maximum size. When creating new connections the thread uses the attributes of the most recent client request that resulted in a new connection being created.
Setting this parameter to "0" will disable maintenance of the buffer minimum.
However, the buffer maximum will still be maintained.
Setting this parameter to a number greater than the maximum pool size(FND_MAX_JDBC_CONNECTIONS) will disable all buffer maintenance.
FND_JDBC_BUFFER_MAX
======================
The buffer maximum is the maximum number of connections that the pool should try to maintain in the available list. During heavy usage, the buffer may exceed this maximum. However, during periods of low usage, the maintenance thread will decrease the buffer size until the buffer maximum is reached.
If the value of this parameter is an integer, (for example "20") the buffer maximum is static. If the value is a percent (for example, "20%"), the buffer maximum is not constant but instead is calculated dynamically as a percent of total pool size. The buffer minimum is also taken into account when
determining a dynamic buffer maximum.
The exact expression used is:
maximum(t) = buffer minimum + ( (FND_JDBC_BUFFER_MAX/100) * size(t) )
where maximum(t) and size(t) are the buffer maximum and pool size at some time t.
The thread is configured to periodically check the buffer size. If the buffer size is greater than the maximum, the thread will remove either the number of available connections specified by FND_JDBC_BUFFER_DECAY_SIZE or the number of connections in excess of the buffer minimum, whichever is smaller. When connections are removed from the available list, the least recently used ones are removed first.
Setting this parameter to100%, or to a number equal to FND_MAXIMUM_JDBC_CONNECTIONS, or to a number less than or equal to FND_JDBC_BUFFER_MIN will effectively prevent the maintenance thread from ever removing any connections.
FND_JDBC_BUFFER_DECAY_INTERVAL
===================================
The buffer decay interval specifies how often the connection pool maintenance thread should check the buffer size. The thread will check the buffer size at most once every FND_JDBC_BUFFER_DECAY_INTERVAL seconds. The actual time between consecutive thread cycles will vary somewhat depending on the JVM load.
This parameter, along with FND_JDBC_BUFFER_DECAY_SIZE, allows the buffer decay rate to be tuned. For example, if the buffer decay size is 2 and the buffer decay interval is one minute, the buffer decay rate will never exceed two connections per minute. When connections are removed, the least recently used ones are removed first.
FND_JDBC_BUFFER_DECAY_SIZE
=============================
The buffer decay size specifies the maximum number of connections that should be removed during any single thread cycle during which the number of available connections is greater than the buffer size. This parameter, along with FND_JDBC_BUFFER_DECAY_INTERVAL, allows the buffer decay rate to be tuned.
FND_JDBC_MAX_WAIT_TIME
=========================
The maximum wait time specifies how much time a client should spend trying to get a connection. The borrow algorithm, used to borrow an object from the pool, contains check points at which the elapsed time is compared to the maximum wait time. If it exceeds the maximum wait time, then a null object will be returned to the client. The pre-configured value for the maximum wait time is
10 seconds.
FND_JDBC_SELECTION_POLICY
============================
The selection policy determines how a connection is selected from the list of available connections for a particular client. The connection pool is pre-configured to use a cost-based selection algorithm, which selects the connection that will require the smallest amount of initialization to match the
client's context.
FND_JDBC_USABLE_CHECK
===========================
The FND_JDBC_USABLE_CHECK parameter governs whether a pl/sql query is performed before giving a connection to a client. The pool checks whether a connection is usable before handing it to a client. This always involves checking that the connection is not null and is not closed. If FND_JDBC_USABLE_CHECK is set to true, then it also verifies that the connection can be used to perform a simple PL/SQL query. (This parameter may have to be set to "true" in order to clean up
connections to a database that has been restarted.)
FND_JDBC_CONTEXT_CHECK
==========================
The FND_JDBC_CONTEXT_CHECK parameter governs whether the AOL security context and NLS state is obtained from the database when the connection is returned to the pool. If FND_JDBC_CONTEXT_CHECK is "true", when the connection is returned to the pool, the AOL security context and NLS state will be obtained from the database. (This is implemented in the DBConnObj.isReusable() method). This check must be done when the connection is returned (rather than when it is borrowed) so that the selection matching algorithm has access to the actual
session context of the connections in the available list.
FND_JDBC_PLSQL_RESET
========================
The PL/SQL reset flag, set using the variable FND_JDBC_PLSQL_RESET, governs whether the PL/SQL state associated with a connection should be freed before the pool hands the connection to the client. By default this flag is false.
If the flag is set by true, by including the line "FND_JDBC_PLSQL_RESET=true" in the .dbc file, each connection to the database will have its PL/SQL state cleared before the pool returns the connection to the client.
This is how it works. After the pool selects a connection from the available list for a client, it initializes the connection. One of the things initialization does is to set a flag that is later used by SessionManager to determine if the apps initialization routine needs to be performed for the connection. When FND_JDBC_PLSQL_RESET has been set to "true", this flag will always be set to true. After the pool initializes the connection, it also checks whether the connection is usable. In this case, this check will include a call to DBMS_SESSION.RESET_PACKAGE, which frees the PL/SQL state. The table below summaries the affect of FND_JDBC_PLSQL_RESET and the other safety check parameters on borrowing a connection from the pool.
The FND_JDBC_PLSQL_RESET parameter has been added to only to address the case where production PL/SQL global bugs are known to exist. The performance of the pool is reduced by setting this flag to true.
Reference : Note 264599.1Purpose
JVM 이 과도한 CPU / Memory를 사용하게 되어 Application Performance에 영향을 미칠때가 있으며 이럴경우 Connection Pool 관련하여 Parameter Tunning을 해야 할때가 있습니다. 이때 사용되는 Parameter들의 의미를 설명하고자 합니다.
The Applications Database Connection Pool is a pool of JDBC database connections that are shared among java applications. Applications obtain connections from the pool by using the getJDBCConnection(...) methods of AppsContext.
Essentially, each AppsContext has a single database connection associated with it at all times.
The AOL/J layer internally borrows and returns this connection to the pool as needed to maintain connection reference that is properly initialized for the current Java tier AOL security context and NLS state.
FND_MAX_JDBC_CONNECTIONS
============================
The maximum pool size is the maximum allowed sum of the number of available connections and thenumber of locked connections. If the pool reaches the maximum size and all connections are locked, new clients will not be able to borrow a connection until one of the current clients has returned one. The default setting for this parameter is essentially unlimited (about 2 billion).
FND_JDBC_BUFFER_MIN
======================
The buffer minimum is the minimum number of connections that the pool should try to maintain in the available list. When the buffer size falls below the buffer minimum, the pool maintenance thread will be notified to create new connections. When notified, the thread will immediately attempt to create the number of connections to fill the difference. New connections will not be created if the pool is already at its maximum size. When creating new connections the thread uses the attributes of the most recent client request that resulted in a new connection being created.
Setting this parameter to "0" will disable maintenance of the buffer minimum.
However, the buffer maximum will still be maintained.
Setting this parameter to a number greater than the maximum pool size(FND_MAX_JDBC_CONNECTIONS) will disable all buffer maintenance.
FND_JDBC_BUFFER_MAX
======================
The buffer maximum is the maximum number of connections that the pool should try to maintain in the available list. During heavy usage, the buffer may exceed this maximum. However, during periods of low usage, the maintenance thread will decrease the buffer size until the buffer maximum is reached.
If the value of this parameter is an integer, (for example "20") the buffer maximum is static. If the value is a percent (for example, "20%"), the buffer maximum is not constant but instead is calculated dynamically as a percent of total pool size. The buffer minimum is also taken into account when
determining a dynamic buffer maximum.
The exact expression used is:
maximum(t) = buffer minimum + ( (FND_JDBC_BUFFER_MAX/100) * size(t) )
where maximum(t) and size(t) are the buffer maximum and pool size at some time t.
The thread is configured to periodically check the buffer size. If the buffer size is greater than the maximum, the thread will remove either the number of available connections specified by FND_JDBC_BUFFER_DECAY_SIZE or the number of connections in excess of the buffer minimum, whichever is smaller. When connections are removed from the available list, the least recently used ones are removed first.
Setting this parameter to100%, or to a number equal to FND_MAXIMUM_JDBC_CONNECTIONS, or to a number less than or equal to FND_JDBC_BUFFER_MIN will effectively prevent the maintenance thread from ever removing any connections.
FND_JDBC_BUFFER_DECAY_INTERVAL
===================================
The buffer decay interval specifies how often the connection pool maintenance thread should check the buffer size. The thread will check the buffer size at most once every FND_JDBC_BUFFER_DECAY_INTERVAL seconds. The actual time between consecutive thread cycles will vary somewhat depending on the JVM load.
This parameter, along with FND_JDBC_BUFFER_DECAY_SIZE, allows the buffer decay rate to be tuned. For example, if the buffer decay size is 2 and the buffer decay interval is one minute, the buffer decay rate will never exceed two connections per minute. When connections are removed, the least recently used ones are removed first.
FND_JDBC_BUFFER_DECAY_SIZE
=============================
The buffer decay size specifies the maximum number of connections that should be removed during any single thread cycle during which the number of available connections is greater than the buffer size. This parameter, along with FND_JDBC_BUFFER_DECAY_INTERVAL, allows the buffer decay rate to be tuned.
FND_JDBC_MAX_WAIT_TIME
=========================
The maximum wait time specifies how much time a client should spend trying to get a connection. The borrow algorithm, used to borrow an object from the pool, contains check points at which the elapsed time is compared to the maximum wait time. If it exceeds the maximum wait time, then a null object will be returned to the client. The pre-configured value for the maximum wait time is
10 seconds.
FND_JDBC_SELECTION_POLICY
============================
The selection policy determines how a connection is selected from the list of available connections for a particular client. The connection pool is pre-configured to use a cost-based selection algorithm, which selects the connection that will require the smallest amount of initialization to match the
client's context.
FND_JDBC_USABLE_CHECK
===========================
The FND_JDBC_USABLE_CHECK parameter governs whether a pl/sql query is performed before giving a connection to a client. The pool checks whether a connection is usable before handing it to a client. This always involves checking that the connection is not null and is not closed. If FND_JDBC_USABLE_CHECK is set to true, then it also verifies that the connection can be used to perform a simple PL/SQL query. (This parameter may have to be set to "true" in order to clean up
connections to a database that has been restarted.)
FND_JDBC_CONTEXT_CHECK
==========================
The FND_JDBC_CONTEXT_CHECK parameter governs whether the AOL security context and NLS state is obtained from the database when the connection is returned to the pool. If FND_JDBC_CONTEXT_CHECK is "true", when the connection is returned to the pool, the AOL security context and NLS state will be obtained from the database. (This is implemented in the DBConnObj.isReusable() method). This check must be done when the connection is returned (rather than when it is borrowed) so that the selection matching algorithm has access to the actual
session context of the connections in the available list.
FND_JDBC_PLSQL_RESET
========================
The PL/SQL reset flag, set using the variable FND_JDBC_PLSQL_RESET, governs whether the PL/SQL state associated with a connection should be freed before the pool hands the connection to the client. By default this flag is false.
If the flag is set by true, by including the line "FND_JDBC_PLSQL_RESET=true" in the .dbc file, each connection to the database will have its PL/SQL state cleared before the pool returns the connection to the client.
This is how it works. After the pool selects a connection from the available list for a client, it initializes the connection. One of the things initialization does is to set a flag that is later used by SessionManager to determine if the apps initialization routine needs to be performed for the connection. When FND_JDBC_PLSQL_RESET has been set to "true", this flag will always be set to true. After the pool initializes the connection, it also checks whether the connection is usable. In this case, this check will include a call to DBMS_SESSION.RESET_PACKAGE, which frees the PL/SQL state. The table below summaries the affect of FND_JDBC_PLSQL_RESET and the other safety check parameters on borrowing a connection from the pool.
The FND_JDBC_PLSQL_RESET parameter has been added to only to address the case where production PL/SQL global bugs are known to exist. The performance of the pool is reduced by setting this flag to true.
Reference : Note 264599.1 -
Oracle Application server connection pool and database links
I am using Oracle application server 10g with connection pools, the db used by the application connects to another oracle db using a database link. My question is when the application starts it creates 10 connections, does it also create x amount of database links as well?
Hi,
Is there any way to use the connection pool or Datasource while connecting to database?If I am using a stateless sesssion bean and using a Data Access layer which just creates a database session to write the persistence toplink objects how I can make use of application server connection pool?Hi Vinod,
Yes, TopLink allows you to use the app server's connection pooling and transaction services. Chapter 2 of the Oracle9iAS TopLink Foundation Library Guide provides details as do the TopLink examples. The easiest way to set this up is by using the sessions.xml file. The sample XML below is from the file <toplink903>\examples\ias\examples\ejb\sessionbean\sessions.xml. Here we are adding the datasource defined in OC4J and specifying that we are using the OC4J transaction controller also.
<login>
<user-name>sa</user-name>
<password></password>
<datasource>java:comp/env/jdbc/ejbJTSDataSource</datasource>
<uses-external-transaction-controller>true</uses-external-transaction-controller>
<uses-external-connection-pool>true</uses-external-connection-pool>
</login>
<external-transaction-controller-class>oracle.toplink.jts.oracle9i.Oracle9iJTSExternalTransactionController</external-transaction-controller-class>
When using this approach you need to change your TopLink code slightly in the EJB methods:
a. Acquire the ACTIVE unit of work from the server
session (again, see the EmployeeSessionEJB code
example) with something like:
UnitOfWork uow = clientSession.getActiveUnitOfWork();
b. Calls to uow.commit() can be ommitted or commented out
because the EJB will handle this. Note that of course
the methods you create in the EJB that are using this
approach must have TX Required (default).
Hope this helps.
Pete -
Windows Service Enterprise Library Data Access Application Blocks Connection Pooling Issue
Hello,
We are developing a windows service using c# .net v 4.5.1 which communicates with SQL database (SQL 2008 R2 x64), communication with SQL server is done using Enterprise Library data access block v 6, The windows service does a file copy process in bulk &
updates the database about the status of file copy, it is observed that as soon as we start the service the number of connections get max out & we start receiving a "Timeout expired. The timeout period elapsed prior to obtaining a connection
from the pool. This may have occurred because all pooled connections were in use and max pool size was reached."
This issue is only observed when we run the code logic by deploying it as a windows service, When we run the exactly same code as a standalone exe (right click -> run as administrator) / non windows service, the connections on database are not exceeded
& we do not receive the above mentioned error.
The code block which makes calls to the database is under the c# "using" statement, hence connection pooling should be handled by default.
Could you please recommend any suggestions on areas which I might have missed on to investigate this issue.
Thanks in advance.Hi
The issue got resolved after refresh the SCOM Data base access service account in SQL 2012.
Unable to launch the operations manager 2012 R2 console after extended the C drive of the SQl server ,getting error "The Data
Access service is either not
running or not yet initialized.
Got to your SQL server -->databases-operationsmanager--security-users--locate the daa service account and refresh.issue fixed and am able to luanch. -
Connection Pool and Database Sessions
Hi,
Is there any way to use the connection pool or Datasource while connecting to database?If I am using a stateless sesssion bean and using a Data Access layer which just creates a database session to write the persistence toplink objects how I can make use of application server connection pool?
Thanks,
VinodHi,
Is there any way to use the connection pool or Datasource while connecting to database?If I am using a stateless sesssion bean and using a Data Access layer which just creates a database session to write the persistence toplink objects how I can make use of application server connection pool?Hi Vinod,
Yes, TopLink allows you to use the app server's connection pooling and transaction services. Chapter 2 of the Oracle9iAS TopLink Foundation Library Guide provides details as do the TopLink examples. The easiest way to set this up is by using the sessions.xml file. The sample XML below is from the file <toplink903>\examples\ias\examples\ejb\sessionbean\sessions.xml. Here we are adding the datasource defined in OC4J and specifying that we are using the OC4J transaction controller also.
<login>
<user-name>sa</user-name>
<password></password>
<datasource>java:comp/env/jdbc/ejbJTSDataSource</datasource>
<uses-external-transaction-controller>true</uses-external-transaction-controller>
<uses-external-connection-pool>true</uses-external-connection-pool>
</login>
<external-transaction-controller-class>oracle.toplink.jts.oracle9i.Oracle9iJTSExternalTransactionController</external-transaction-controller-class>
When using this approach you need to change your TopLink code slightly in the EJB methods:
a. Acquire the ACTIVE unit of work from the server
session (again, see the EmployeeSessionEJB code
example) with something like:
UnitOfWork uow = clientSession.getActiveUnitOfWork();
b. Calls to uow.commit() can be ommitted or commented out
because the EJB will handle this. Note that of course
the methods you create in the EJB that are using this
approach must have TX Required (default).
Hope this helps.
Pete -
Listener EA2: database connection pool and connection revalidation
Hi all,
As one can expect from early adopter release there could be some bugs but I can't find any references in forum to my situation:
* My 11g XE database and listener are starting as windows services when server boots operating system (Windows Server 2003 R2).
* I configured my web server (unsupported Jetty 9.0.0.M1) to start as windows service when operating system starts.
* Apex Listener 2.0.0.268.17.05 configured to connect with XE using JDBC thin driver with default settings (initial pool size 3, max statements 10, min connections 1, max connections 10, inactivity timeout 1800, abandoned connection timeout 900)
* Because web server starts a bit faster than Oracle database when apex connects first time it gets "ORA-12528, TNS:listener: all appropriate instances are blocking new connections" (could be that database still starting but already registered service with listener)
* From listener.log file I can see that all further connections made from Apex listener succeeds
* When I try to open any apex page with browser I am getting 404 error and apex listener logs error (*time is 2 days after system startup*):
2012-11-30 3:56:02 PM oracle.dbtools.common.config.db.DatabaseConfig badConfiguration
SEVERE: The pool named: apex is not correctly configured, error: Listener refused the connection with the following error:
ORA-12528, TNS:listener: all appropriate instances are blocking new connections
ConnectionPoolException [error=BAD_CONFIGURATION]
at oracle.dbtools.common.jdbc.ConnectionPoolException.badConfiguration(ConnectionPoolException.java:62)
at oracle.dbtools.common.config.db.DatabaseConfig.badConfiguration(DatabaseConfig.java:146)
at oracle.dbtools.common.config.db.DatabaseConfig.createPool(DatabaseConfig.java:168)
at oracle.dbtools.common.config.db.DatabaseConfig.getConnection(DatabaseConfig.java:68)
at oracle.dbtools.common.jdbc.ora.OraPrincipal.connection(OraPrincipal.java:25)
at oracle.dbtools.apex.ModApexContext.getConnection(ModApexContext.java:320)
at oracle.dbtools.apex.Procedure.getProcedure(Procedure.java:166)
at oracle.dbtools.apex.OWA.validateProcedure(OWA.java:384)
at oracle.dbtools.apex.security.Security.isValidRequest(Security.java:171)
at oracle.dbtools.apex.ModApex.validateRequest(ModApex.java:233)
at oracle.dbtools.apex.ModApex.doGet(ModApex.java:79)
at oracle.dbtools.apex.ModApex.service(ModApex.java:263)
at oracle.dbtools.rt.web.HttpEndpointBase.modApex(HttpEndpointBase.java:288)
at oracle.dbtools.rt.web.HttpEndpointBase.service(HttpEndpointBase.java:127)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:848)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:665)
<... Jetty web server stack ...>
at java.lang.Thread.run(Unknown Source)
2012-11-30 3:56:02 PM oracle.dbtools.rt.web.HttpEndpointBase modApex
* Oracle listener log for same time (no errors here):
30-NOV-2012 15:56:01 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))(SERVICE_NAME=xe)(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1078)) * establish * xe * 0
30-NOV-2012 15:56:01 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))(SERVICE_NAME=xe)(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1079)) * establish * xe * 0
30-NOV-2012 15:56:01 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))(SERVICE_NAME=xe)(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1080)) * establish * xe * 0
30-NOV-2012 15:56:01 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))(SERVICE_NAME=xe)(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1081)) * establish * xe * 0
* For some reason apex listener keeps first connection status and won't try to establish new connection if first attempt finished with ORA-12528
* The same scenario is valid when at time of web server start oracle database/listener is not available - even if database and listener starts and apex successfully establishes further connections all apex pages gets 404 error
* If I restart web server windows service (while oracle db and listener still running) browser opens apex pages without errors and apex listener does not log any errors
* I know that I can avoid this error delaying start of web server windows service but it would be nice to have production release 2.x without such bugsHi,
Is there any way to use the connection pool or Datasource while connecting to database?If I am using a stateless sesssion bean and using a Data Access layer which just creates a database session to write the persistence toplink objects how I can make use of application server connection pool?Hi Vinod,
Yes, TopLink allows you to use the app server's connection pooling and transaction services. Chapter 2 of the Oracle9iAS TopLink Foundation Library Guide provides details as do the TopLink examples. The easiest way to set this up is by using the sessions.xml file. The sample XML below is from the file <toplink903>\examples\ias\examples\ejb\sessionbean\sessions.xml. Here we are adding the datasource defined in OC4J and specifying that we are using the OC4J transaction controller also.
<login>
<user-name>sa</user-name>
<password></password>
<datasource>java:comp/env/jdbc/ejbJTSDataSource</datasource>
<uses-external-transaction-controller>true</uses-external-transaction-controller>
<uses-external-connection-pool>true</uses-external-connection-pool>
</login>
<external-transaction-controller-class>oracle.toplink.jts.oracle9i.Oracle9iJTSExternalTransactionController</external-transaction-controller-class>
When using this approach you need to change your TopLink code slightly in the EJB methods:
a. Acquire the ACTIVE unit of work from the server
session (again, see the EmployeeSessionEJB code
example) with something like:
UnitOfWork uow = clientSession.getActiveUnitOfWork();
b. Calls to uow.commit() can be ommitted or commented out
because the EJB will handle this. Note that of course
the methods you create in the EJB that are using this
approach must have TX Required (default).
Hope this helps.
Pete -
Hi All ,
i am developing a struts based web-application with JBoss 4.0.5 as Application Server and Oracle 10g Express edition .
I am configuring my application for connection pooling .
I have tried following methods :
1. Oracle Connection Pooling following thius link http://www.lc.leidenuniv.nl/awcourse/oracle/java.920/a96654/connpoca.htm
2. Configuring Jboss's Internal Container Level Connection pooling simply creating the datasources
3. JDBC level Connection Pooling
but unluckily did not succeed in any of these method .
The application works OK with Second method but When it is being hit with 200 request/second The pool gets exhaulsted .
i am unable to decide which approach i should be using as my application can receive large no. of requests around 1000/sec ?
Please help me out ,
Tell some useful link if possible ..
Regards JasdeepThe pool can't do magic. If your database operations take ten seconds each, you get 1000 requests a second, and you have a pool size of 200, the pool will effectively empty instantly.
You need to get some measurements of how long the typical transactions last and figure out an appropriate pool size for that. If it's more than the database can handle then you're going to have to upgrade.
It's that simple. -
Regarding connection pooling in java mail
Hi,
Im implementing enterprise application which has ability of sending/receiving emails. Im using java mail API 14.3. I have implemented the application level connection pooling which keep track of open folders, perform the time-out and other tasks. The connection pooling setting of IMAPStore is default setting. When we run our application in high load we get StoreClosedExcepton (Socket closed exception). My assumption is that when we perform some operation on folder, java mail also sends the noop command for store connection so there is no chance of store getting timeout.
Is there anything wrong in my understanding?JavaMail does not do anything to keep the connection "alive". Servers are free to close
connections that have been unused for too long (usually 30 minutes). If you need to
keep the connection alive, you'll need to do some operation periodically, such as checking
the number of messages in the folder. Even that doesn't guard against server or network
failures, of course, so you always have to be prepared for a StoreClosedException or
FolderClosedException. -
Oracle: slow performance with SELECT using ojdbc14 and connection pooling
Hello,
i'm working hard the last days to solve a performance problem with our customer using a oracle 10g database. For testing I used our oracle 9.2.0.1.0 database which shows the same symptoms. All doing solved nothing: the performance while using this oracle is much slower than other databases. This result I cannot trust and so I need some advice. What is missing to improve the performance on the java side?
The webapplication I use runs fast on MySQL 4.x and SQLServer 2000, but on the above mentioned Oracle it was always 4 times slower. The webapplication uses a lot of simple SELECT-Statements without complicated joins and so on (because it should run on many different databases). Doing some days of creating tests within this webapplication, I was not able to find any entrance point for a change. All databases server I'm using, having only the default configurations after a common installation.
To reduce the complexity I wrote a simple java application with connection pooling using only the latest libraries from apache-commons(dbcp, pool), and the latest ojdbc14 for oracle 9.2.
First the results than the code: MySQL needed less than 1000 millisecond, SQLServer around 1000 milliseconds and Oracle over 2000 milliseconds. I stopped pooling and the results are for Oracle even worse: over 18000 milliseconds (mysql:2500, sqlserver:4100).
I changed the classes for Oracle and used the class oracle.jdbc.pool.OracleConnectionCacheImpl from the ojdbc14-library. No difference (around 100 milliseconds more or less).
The only Select-Statement works on this table, which has one index on HICTGID.
It contains 259 entrances.:
CREATE TABLE HIERARCHYCATEGORY (
HICTGID NUMBER (19) NOT NULL,
HICTGLEVEL NUMBER (10) NOT NULL,
HICTGEXTID NUMBER (19) NOT NULL,
HICTGEXTPARENTID NUMBER (19) NOT NULL,
HICTGNAME VARCHAR2(255) NOT NULL
);The application simply loops through this table using
SELECT Hictgid, Hictgname FROM HIERARCHYCATEGORY WHERE HICTGID = ?, but I always open a connection before this query and closes this connection afterwards. So I use the pooling as much as possible. That's all SQL I'm using.
protected static DataSource setupDataSource(String sDriver, String sUrl, String sUser, String sPwd) throws SQLException {
BasicDataSource ds = new BasicDataSource();
ds.setDriverClassName(sDriver);
ds.setUsername(sUser);
ds.setPassword(sPwd);
ds.setUrl(sUrl);
// The maximum number of active connections:
ds.setMaxActive(3);
// The maximum number of active connections that can remain idle in the pool,
// without extra ones being released, or zero for no limit:
ds.setMaxIdle(3);
// The maximum number of milliseconds that the pool will wait (when there are no available connections)
// for a connection to be returned before throwing an exception, or -1 to wait indefinitely:
ds.setMaxWait(3000);
return ds;
}I can switch by using external properties between three databases (oracle, mysql and sqlserver) and if I want I can switch pooling off. And all actions I'm interested are logged by Log4J.
public static Connection getConnection() throws SQLException {
Connection result = null;
String sJdbcDriver = m_oJbProp.getString("jdbcDriver");
String sJdbcUrl = m_oJbProp.getString("databaseConnection");
String sJdbcUser = m_oJbProp.getString("dbUsername");
String sJdbcPwd = m_oJbProp.getString("dbPassword");
try {
if (m_oJbProp.getString("useConnectionPooling").equals("true")) {
if (log.isDebugEnabled()) {
log.debug("ConnectionPooling true");
if(null == m_ds) {
m_ds = setupDataSource(sJdbcDriver,sJdbcUrl,sJdbcUser,sJdbcPwd);
if (log.isDebugEnabled()) {
log.debug("DataSource created");
result = m_ds.getConnection();
} else {
// No connection pooling:
if (log.isDebugEnabled()) {
log.debug("ConnectionPooling false");
try {
Class.forName(sJdbcDriver);
result = DriverManager.getConnection(sJdbcUrl, sJdbcUser, sJdbcPwd);
} catch (ClassNotFoundException cnf) {
log.error("Exception: Class Not Found. ", cnf);
System.exit(0);
(.. ErrorHandling ...)Here is the code fragment which is doing the work:
StringBuffer sb = new StringBuffer();
while (lNextBottom <= lNextCeiling) {
con = getConnection();
innerSelStmt = con.prepareStatement("SELECT Hictgid, Hictgname FROM HIERARCHYCATEGORY WHERE HICTGID = ?");
innerSelStmt.setLong(1, lNextBottom);
rsInner = innerSelStmt.executeQuery();
if ((rsInner != null) && (rsInner.next())) {
sb.append(rsInner.getLong(1) + ", " + rsInner.getString(2) + "\r");
if (log.isDebugEnabled()) {
log.debug("Inner Statement: " + rsInner.getLong(1) + "\r");
rsInner.close();
con.close();
lNextBottom++;
if (log.isInfoEnabled()) {
log.info("\rResult values: Hictgid, Hictgname \r");
log.info(sb.toString());
}and the main method:
public static void main(String[] args) {
try {
long lStartTime = System.currentTimeMillis();
JdbcBasic oJb = new JdbcBasic();
boolean bSuccess = false;
bSuccess = oJb.getHierarchycategories();
if (log.isInfoEnabled()) {
log.info("Running time: " + (System.currentTimeMillis() - lStartTime));
if (null != m_ds) {
printDataSourceStats(m_ds);
shutdownDataSource(m_ds);
if (log.isInfoEnabled()) {
log.info("Datasource closed.");
} catch (SQLException sqe) {
log.error("SQLException within main-method", sqe);
}My database values are
databaseConnection=jdbc:oracle:thin:@SERVERDB:1521:ora
jdbcDriver=oracle.jdbc.driver.OracleDriver
databaseConnection=jdbc:jtds:sqlserver://SERVERDB:1433/testdb
jdbcDriver=net.sourceforge.jtds.jdbc.Driver
databaseConnection=jdbc:mysql://localhost/testdb
jdbcDriver=com.mysql.jdbc.Driver
dbUsername=testusr
dbPassword=testpwdThanks for your reading and maybe for your help.A few comments.
There is of course another difference between your test cases then just the database. There is also the driver. And I suspect that in at least the case with the jtds driver it is helping you along where you are doing something silly and the Oracle driver is not.
Before I explain the next part I would say the speed differences between MS-SQL and MySQL look about right I think you are aiming here for MS-SQL level performance not MySQL. (For a bunch of reasons MySQL is inherently faster but there are MANY drawbacks as well which have been well discussed on previous threads)
Here is where I believe your problem lies
while (lNextBottom <= lNextCeiling) {
con = getConnection();
innerSelStmt = con.prepareStatement("SELECT Hictgid, Hictgname FROM HIERARCHYCATEGORY WHERE HICTGID = ?");
innerSelStmt.setLong(1, lNextBottom);
rsInner = innerSelStmt.executeQuery();
if ((rsInner != null) && (rsInner.next())) {
sb.append(rsInner.getLong(1) + ", " + rsInner.getString(2) + "\r");
if (log.isDebugEnabled()) {
log.debug("Inner Statement: " + rsInner.getLong(1) + "\r");
rsInner.close();
con.close();
lNextBottom++;
}There at least four things that are wrong with above.
1) Why are you preparing the statement INSIDE the loop. Let us for a moment say that the loop will spin 100 times. That means that you are preparing the same statement 100 times. This is bad. It is also very relevant because for example the Jtds driver is going to be caching the prepared statements you make so that actually while you try and prepare it 100 times it only actually does it once... but in Oracle I don't know what it is doing for sure but if it is preparing on each pass well than that bit of it is going take 100 times longer then it should.
2) You are opening and closing the connection on each pass through the loop... also a terrible idea. You need to fix this first so that you can repeatedly use the same prepared statement.
3) Why are you looping in the first place? More on this later.
4) Where do you close the PreparedStatement? It doesn't look like you do.
Okay so for starters your loop should look a lot more like this...
code]
con = getConnection();
innerSelStmt = con.prepareStatement("SELECT Hictgid, Hictgname FROM HIERARCHYCATEGORY WHERE HICTGID = ?");
while (lNextBottom <= lNextCeiling) {
innerSelStmt.setLong(1, lNextBottom);
rsInner = innerSelStmt.executeQuery();
if ((rsInner != null) && (rsInner.next())) {
sb.append(rsInner.getLong(1) + ", " + rsInner.getString(2) + "\r");
rsInner.close();
lNextBottom++;
innerSelStmt.close();
con.close();
I think the code above (and you can put your debug stuff back if you want) which uses ONE connection and ONE prepared Statement will improve your performance dramatically.
The other question though I would as is why in the hell you are doing 100 or whatever number of queries anyway. This can be done all in ONE query which again will improve performance.
Your query and such should look like this I think.
String sql = "SELECT Hictgid, Hictgname FROM HIERARCHYCATEGORY WHERE HICTGID >=? AND HICTGID<=?";
PreparedStatement ps = conn.prepareStatement(sql);
ps.setLong(1,lNextBottom );
ps.setLong(2,lNextCeiling);
ResultSet rs = ps.executeQuery();
while(rs.next()){
// your appending to string buffer code goes here
}and I can't understand why you're not doing that in the first place. -
Connection Pooling .. Cant Close Them!
Hi,
I have an application that goes off to a SQL Server database and pulls back certain data. I am currently just opening a new connection, and then getting the data and then closing the connection.
This is proving to be quite expensive in resources, and is very slow.
I took the step to move to connection pooling.
What I have found is that it DRAMATICALLY increased the speed of returning the data, though when I look at the processors running on the database, there seem to be heaps of connections on there, and they dont seem to close down or time out.
Is this usually the way this works?
Thanks
M
Here is my connection pooling code.
ConnectionPool.java
package con;
import java.sql.*;
import java.util.*;
public class ConnectionPool {
// JDBC Driver Name
private String driver = null;
// URL of database
private String url = null;
// Initial number of connections.
private int size = 5;
// Username
private String username = new String("username");
// Password
private String password = new String("password");
// Vector of JDBC Connections
private Vector pool = null;
public ConnectionPool() {
// Set the value of the JDBC Driver
public void setDriver(String value) {
if ( value != null ) {
driver = value;
// Get the value of the JDBC Driver
public String getDriver() {
return driver;
// Set the URL Pointing to the Datasource
public void setURL(String value ) {
if ( value != null ) {
url = value;
// Get the URL Pointing to the Datasource
public String getURL() {
return url;
// Set the initial number of connections
public void setSize(int value) {
if ( value > 1 ) {
size = value;
// Get the initial number of connections
public int getSize() {
return size;
// Set the username
public void setUsername(String value) {
if ( value != null ) {
username = value;
// Get the username
public String getUserName() {
return username;
// Set the password
public void setPassword(String value) {
if ( value != null ) {
password = value;
// Get the password
public String getPassword() {
return password;
// Creates and returns a connection
private Connection createConnection() throws Exception {
Connection con = null;
// Create a Connection
con = DriverManager.getConnection(url,
username, password);
return con;
// Initialize the pool
public synchronized void initializePool() throws Exception {
// Check our initial values
if ( driver == null ) {
throw new Exception("No Driver Name Specified!");
if ( url == null ) {
throw new Exception("No URL Specified!");
if ( size < 1 ) {
throw new Exception("Pool size is less than 1!");
// Create the Connections
try {
// Load the Driver class file
Class.forName(driver);
// Create Connections based on the size member
for ( int x = 0; x < size; x++ ) {
Connection con = createConnection();
if ( con != null ) {
// Create a PooledConnection to encapsulate the
// real JDBC Connection
PooledConnection pcon = new PooledConnection(con);
// Add the Connection to the pool.
addConnection(pcon);
catch (Exception e) {
System.err.println(e.getMessage());
throw new Exception(e.getMessage());
// Adds the PooledConnection to the pool
private void addConnection(PooledConnection value) {
// If the pool is null, create a new vector
// with the initial size of "size"
if ( pool == null ) {
pool = new Vector(size);
// Add the PooledConnection Object to the vector
pool.addElement(value);
public synchronized void releaseConnection(Connection con) {
// find the PooledConnection Object
for ( int x = 0; x < pool.size(); x++ ) {
PooledConnection pcon =
(PooledConnection)pool.elementAt(x);
// Check for correct Connection
if ( pcon.getConnection() == con ) {
System.err.println("Releasing Connection " + x);
// Set its inuse attribute to false, which
// releases it for use
pcon.setInUse(false);
break;
// Find an available connection
public synchronized Connection getConnection()
throws Exception {
PooledConnection pcon = null;
// find a connection not in use
for ( int x = 0; x < pool.size(); x++ ) {
pcon = (PooledConnection)pool.elementAt(x);
// Check to see if the Connection is in use
if ( pcon.inUse() == false ) {
// Mark it as in use
pcon.setInUse(true);
// return the JDBC Connection stored in the
// PooledConnection object
return pcon.getConnection();
// Could not find a free connection,
// create and add a new one
try {
// Create a new JDBC Connection
Connection con = createConnection();
// Create a new PooledConnection, passing it the JDBC
// Connection
pcon = new PooledConnection(con);
// Mark the connection as in use
pcon.setInUse(true);
// Add the new PooledConnection object to the pool
pool.addElement(pcon);
catch (Exception e) {
System.err.println(e.getMessage());
throw new Exception(e.getMessage());
// return the new Connection
return pcon.getConnection();
// When shutting down the pool, you need to first empty it.
public synchronized void emptyPool() {
// Iterate over the entire pool closing the
// JDBC Connections.
for ( int x = 0; x < pool.size(); x++ ) {
System.err.println("Closing JDBC Connection " + x);
PooledConnection pcon =
(PooledConnection)pool.elementAt(x);
// If the PooledConnection is not in use, close it
if ( pcon.inUse() == false ) {
pcon.close();
else {
// If it is still in use, sleep for 30 seconds and
// force close.
try {
java.lang.Thread.sleep(30000);
pcon.close();
catch (InterruptedException ie) {
System.err.println(ie.getMessage());
PooledConnection.java
package con;
import java.sql.*;
public class PooledConnection {
// Real JDBC Connection
private Connection connection = null;
// boolean flag used to determine if connection is in use
private boolean inuse = false;
// Constructor that takes the passed in JDBC Connection
// and stores it in the connection attribute.
public PooledConnection(Connection value) {
if ( value != null ) {
connection = value;
// Returns a reference to the JDBC Connection
public Connection getConnection() {
// get the JDBC Connection
return connection;
// Set the status of the PooledConnection.
public void setInUse(boolean value) {
inuse = value;
// Returns the current status of the PooledConnection.
public boolean inUse() {
return inuse;
// Close the real JDBC Connection
public void close() {
try {
connection.close();
catch (SQLException sqle) {
System.err.println(sqle.getMessage());
<html>
<body>
<%@ page errorPage="errorpage.jsp" %>
<%@ page import="java.util.*" %>
<%@ page import="java.sql.*" %>
<!-- Instantiate the ConnectionPool bean with an id of "pool" -->
<jsp:useBean id="pool" scope="application" class="con.ConnectionPool" />
<%
Connection con = null;
try {
// The pool is not initialized
if ( pool.getDriver() == null ) {
// initialize the pool
pool.setDriver("sun.jdbc.odbc.JdbcOdbcDriver");
pool.setURL("jdbc:odbc:Stuff");
pool.setSize(5);
pool.initializePool();
// Get a connection from the ConnectionPool
con = pool.getConnection();
// Create the statement
Statement statement = con.createStatement();
// Use the created statement to SELECT the DATA
// FROM the Titles Table.
ResultSet rs = statement.executeQuery("SELECT * " +
"FROM Titles");
// Iterate over the ResultSet
%>
<!-- Add an HTML table to format the results -->
<center>
<table border="1" cellspacing="0" cellpadding="2"width="500">
<tr>
<th>Title</th><th>Rating</th><th>Price</th><th>Quantity</th>
<%
while ( rs.next() ) {
// get the title_name, which is a String
out.println("<tr>\n<td>" +
rs.getString("title_name") + "</td>");
// get the rating
out.println("<td align=\"center\">" +
rs.getString("rating") + "</td>");
// get the price
out.println("<td align=\"center\">" +
rs.getString("price") + "</td>");
// get the quantity
out.println("<td align=\"center\">" +
rs.getString("quantity") + "</td>\n</tr>");
// Close the ResultSet
rs.close();
out.println("</table></center>");
catch (IOException ioe) {
out.println(ioe.getMessage());
catch (SQLException sqle) {
out.println(sqle.getMessage());
catch (ClassNotFoundException cnfe) {
out.println(cnfe.getMessage());
catch (Exception e) {
out.println(e.getMessage());
finally {
try {
if ( con != null ) {
// release the connection no matter what
pool.releaseConnection(con);
catch (Exception e) {
out.println(e.getMessage());
%>
</body>
</html>No, it's not the same....
Here....
The basic idea behind connection pooling is simple. In an application that opens and closes many database connections, it is efficient to keep unused Connection objects in a pool for future re-use. This saves the overhead of having to open a new physical connection each time a connection is opened.
The JdbcConnectionPool.getConnection() method tries to save the overhead of opening a new connection by using a connection that is already in the pool. When a lookup is performed to find a connection in the pool, a match is found if the user name equals the user name that was originally used to create the pooled connection. Password is not considered when trying to match a user. A new connection is requested from the factory only if no match is found in the pool.
When an application uses connection pooling, a connection should always be explicitly closed when no longer in use. This allows the connection to be returned to the pool for later use, which improves performance.
The factory which creates connections for the pool should use the same property settings for all of them, except for the user name and password. A connection pool, therefore, accesses one database, and all its connections have the same JDBC connection property settings (but can have different usernames/passwords). -
How to use JDBC Connection Pools in a standalone application?
Hi, there,
I have a question about how to use JDBC Connection Pools in an application. I know well about connection pool itself, but I am not quite sure how to keep the pool management object alive all the time to avoid being destroyed by garbage collection.
for example, at the website: http://www.developer.com/java/other/article.php/626291, there is a simple connection pool implementation. there are three classes:JDBCConnection, the application's gateway to the database; JDBCConnectionImpl, the real class/object to provide connection; and JDBCPool, the management class to manage connection pool composed by JDBCConnectionImpl. JDBCPool is designed by Singleton pattern to make sure only one instance. supposing there is only one client to use connection for many times, I guess it's ok because this client first needs instantiate JDBCPool and JDBCConnectionImpl and then will hold the reference to JDBCPool all the time. but how about many clients want to use this JDBCPool? supposing client1 finishes using JDBCPool and quits, then JDBCPool will be destroyed by garbage collection since there is no reference to it, also all the connections of JDBCConnectionImpl in this pool will be destroyed too. that means the next client needs recreate pool and connections! so my question is that if there is a way to keep pool management instance alive all the time to provide connection to any client at any time. I guess maybe I can set the pool management class as daemon thread to solve this problem, but I am not quite sure. besides, there is some other problems about daemon thread, for example, how to make sure there is only one daemon instance? how to quit it gracefully? because once the whole application quits, the daemon thread also quits by force. in that case, all the connections in the pool won't get chance to close.
I know there is another solution by JNDI if we develop servlet application. Tomcat provides an easy way to setup JNDI database pooling source that is available to JSP and Servlet. but how about a standalone application? I mean there is no JNDI service provider. it seems a good solution to combine Commons DBCP with JNID or Apache's Naming (http://jakarta.apache.org/commons/dbcp/index.html). but still, I don't know how to keep pool management instance alive all the time. once we create a JNDI enviroment or naming, if it will save in the memory automatically all the time? or we must implement it as a daemon thread?
any hint will be great apprieciated!
SamTo my knoledge the pool management instance stays alive as long as the pool is alive. What you have to figure out is how to keep a reference to it if you need to later access it.
-
How database connection pooling works in a application
Hi Guys,
I am new to Java and looking into best way of doing J2ee database conectivity. I am using Eclipse galileo3.5 J2EE with Mysql database and Tomcate 6.0.
I am developing an email application where I need to implement MVC model for my webapplication, using jsp for presentation, servlet for control and java beans for model.
I came across two tutorial for database connection pooling as given below.
Eclipse Corner Article: Creating Database Web Applications with Eclipse - In this tutorial connection pooling is configure in Tomcate 6.0
It says Copy and paste the following into your context.xml file (you may have to click on the Source tab at the bottom of the editor to be able to paste). This defines a DataSource with the name "jdbc/SampleDB". Our application will retrieve database connections from the pool using this name.
<?xml version="1.0" encoding="UTF-8"?>
<Context>
<Resource name="jdbc/SampleDB" auth="Container"
type="javax.sql.DataSource"
username="app" password="app"
driverClassName="org.apache.derby.jdbc.ClientDrive r"
url="jdbc:derby://localhost:1527/sample"
maxActive="8" />
</Context>
Where as in second tutorial - http://www.roseindia.net/answers/viewanswers/2838.html
It uses java bean for connection pooling and then use straight way in JSP and no Servlet used.
conpool.jsp
<%@page import="java.sql.Connection"%>
<jsp:useBean id="pl" class="com.CoreJava.ConnectionPooling"/>
<% Connection con = pl.getConnection(); %>
//do something using con
connectionPooling.java
import com.mysql.jdbc.jdbc2.optional.MysqlConnectionPoolD ataSource;
public class ConnectionPooling
static Connection con=null;
public static Connection getConnection()
try
MysqlConnectionPoolDataSource po=new MysqlConnectionPoolDataSource();
po.setServerName("localhost");
po.setPortNumber(3306);
po.setDatabaseName("mydatabase"); //changeur database name
po.setUser("root");//ur username
po.setPassword("");//ur password
con = po.getConnection();
catch(Exception e)
System.out.println("Exception Connection :"+e);
return con;
Please some one explain which is the best way of doing connection pooling to the database by using MVC pattern
Please if some one advise me how to use MVC architecture for simple email application and database connectivty.
Thanks>
>
Where as in second tutorial - http://www.roseindia.net/answers/viewanswers/2838.html
Never EVER use roseindia. It is terrible shit.
[http://balusc.blogspot.com/2008/06/what-is-it-with-roseindia.html]
The correct answer is what you found in the eclipse article. And you can read the Tomcat docs for more.
As per usual the code you have posted from Roseindia is a big pile of rubbish that was written by a complete idiot. I mean the person who wrote it apparently doesn't know much Java at all. Let alone JDBC. Or Connection pools. Or J2EE. It's not the worst I've seen from them but it's pretty bad. -
Creating a connection pool using Oracle 10g, Sun ONE Application Serve 8.1
Has any one succesfully configured Oracle 10g to work with Sun ONE Application Server 8.1 on Windows 2000 server service pack 4? I am embarking on a new J2EE project and I need to configure it as soon as possible.
I haven't done it myself on that particular service pack, but I don't see why it should be any different than configuring a connection pool on other vanilla win2k/other OSes.
Would you please try and let this forum know?
thanks. -
Creating a connection pool using SQL Server 2000, Sun ONE Application Serve
Has any one succesfully configured SQL Server 2000 to work with Sun ONE Application Server 7 on Windows 2000 server service pack 4? I am embarking on a new J2EE project and I need to configure it as soon as possible.
The problem I am having is that, when I ping the data souce name, there is a connection error.
I have set the data source name and other details as follows:
Under JDBC, I have set the parameters for the connection pool as follows:
Data Source Name: com.microsoft.jdbc.sqlserver.SQLServerDriver
Database Name: jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=Test
User: test
Password: test
In the JVM settings page, I have set the prefix class path as follows for the location of the Microsoft JDBC
drivers that I downloaded as follows:
c:\microsoft\drivers/lib/msbase.jar
c:\microsoft\drivers/lib/msutil.jar
c:\microsoft\drivers/lib/mssqlserver.jar
Under JVM Options, there is a strange setting which I don't understand: perhaps this is the cause of the
connction error?
-Djdbc.drivers=com.pointbase.jdbc.jdbcUniversalDriver
Please help????I'm in a similar boat...
Trying to setup AS7 JDBC and followed the instructions on the link you provided and get the following exception. I kept the case the same, thinking 'setpassword" was incorrect, so I tried changing the property to "Password", but get the same exception but it points to "setPassword" instead.
SEVERE: RAR5041:Cannot get jdbc connection
com.sun.enterprise.repository.J2EEResourceException
java.lang.NoSuchMethodException: setpassword
at com.sun.enterprise.repository.JdbcConnectionPool.createDataSource(JdbcConnectionPool.java:243)
at com.sun.enterprise.resource.JdbcUrlAllocator.createResource(JdbcUrlAllocator.java:80)
at com.sun.enterprise.resource.IASNonSharedResourcePool.createSteadyResources(IASNonSharedResourcePool.java:856)
at com.sun.enterprise.resource.IASNonSharedResourcePool.initPool(IASNonSharedResourcePool.java:416)
at com.sun.enterprise.resource.IASNonSharedResourcePool.internalGetResource(IASNonSharedResourcePool.java:625)
at com.sun.enterprise.resource.IASNonSharedResourcePool.getResource(IASNonSharedResourcePool.java:520)
at com.sun.enterprise.resource.PoolManagerImpl.getResourceFromPool(PoolManagerImpl.java:263)
at com.sun.enterprise.resource.JdbcXAConnection.<init>(JdbcXAConnection.java:74)
at com.sun.enterprise.resource.Jdbc10XaAllocator.createResource(Jdbc10XaAllocator.java:94)
at com.sun.enterprise.resource.IASNonSharedResourcePool.createSteadyResources(IASNonSharedResourcePool.java:856)
at com.sun.enterprise.resource.IASNonSharedResourcePool.initPool(IASNonSharedResourcePool.java:416)
at com.sun.enterprise.resource.IASNonSharedResourcePool.internalGetResource(IASNonSharedResourcePool.java:625)
at com.sun.enterprise.resource.IASNonSharedResourcePool.getResource(IASNonSharedResourcePool.java:520)
at com.sun.enterprise.resource.PoolManagerImpl.getResourceFromPool(PoolManagerImpl.java:263)
at com.sun.enterprise.resource.PoolManagerImpl.getResource(PoolManagerImpl.java:170)
at com.sun.enterprise.resource.JdbcDataSource.internalGetConnection(JdbcDataSource.java:241)
at com.sun.enterprise.resource.JdbcDataSource.getConnection(JdbcDataSource.java:98)
at com.rvi.database.jdbcConnection.getConnection(jdbcConnection.java:93)
at com.webapp.database.ArticlesDAO.selectByYear(ArticlesDAO.java:102)
at com.webapp.actions.ArticleAction.list(ArticleAction.java:96)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:280)
at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:216)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:507)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.StandardWrapperValve.invokeServletService(StandardWrapperValve.java:720)
at org.apache.catalina.core.StandardWrapperValve.access$000(StandardWrapperValve.java:118)
at org.apache.catalina.core.StandardWrapperValve$1.run(StandardWrapperValve.java:278)
at java.security.AccessController.doPrivileged(Native Method)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:274)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:505)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:212)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:203)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:505)
at com.iplanet.ias.web.connector.nsapi.NSAPIProcessor.process(NSAPIProcessor.java:157)
at com.iplanet.ias.web.WebContainer.service(WebContainer.java:598) -
Connection pool for big web application
hi,
i am developing an application which had more then 20 classes and each class use databases.
i made an connection bean and use it for database connectivity but as my code expand and my application run for longer time i start getting error of connection limit.
then i start using connection pool. in this i start using one connection for whole application.
now i want that my
1-whole application use that connection pool and i dont need to initialize it in different classes.
2- The main problem is that may at a time i have to connect database with different user and these connections should remain active.
my application will be used for enterprise level and remain active for months .
following is my connection pool
public class ConnectionPool implements Runnable
private Log log=new Log();
private String driver, url, username, password;
private int maxConnections;
private boolean waitIfBusy;
private Vector availableConnections, busyConnections;
private boolean connectionPending = false;
public ConnectionPool(String driver, String url,String username, String password,int initialConnections, int maxConnections, boolean waitIfBusy)
this.driver = driver;
this.url = url;
this.username = username;
this.password = password;
this.maxConnections = maxConnections;
this.waitIfBusy = waitIfBusy;
if (initialConnections > maxConnections)
initialConnections = maxConnections;
availableConnections = new Vector(initialConnections);
busyConnections = new Vector();
try
for(int i=0; i<initialConnections; i++)
availableConnections.addElement(makeNewConnection());
catch(Exception e)
log.write(e.getMessage());
}//EO constructor
public synchronized Connection getConnection()
if (!availableConnections.isEmpty())
log.write("Total connections="+availableConnections.size());
Connection existingConnection = (Connection)availableConnections.lastElement();
int lastIndex = availableConnections.size() - 1;
availableConnections.removeElementAt(lastIndex);
// If connection on available list is closed (e.g.,it timed out), then remove it from available list
// and repeat the process of obtaining a connection. Also wake up threads that were waiting for a connection because maxConnection limit was reached.
try
if (existingConnection.isClosed())
notifyAll(); // Freed up a spot for anybody waiting
return(getConnection());
else
log.write( "in available connection" );
busyConnections.addElement(existingConnection);
return(existingConnection);
catch(SQLException se)
log.write(se.getMessage());
} else {
// Three possible cases:
// 1) You haven't reached maxConnections limit. So establish one in the background if there isn't
// already one pending, then wait for the next available connection (whether or not it was the newly established one).
// 2) You reached maxConnections limit and waitIfBusy flag is false. Throw SQLException in such a case.
// 3) You reached maxConnections limit and waitIfBusy flag is true. Then do the same thing as in second
// part of step 1: wait for next available connection.
if ((totalConnections() < maxConnections) && !connectionPending)
makeBackgroundConnection();
else if (!waitIfBusy)
log.write("Connection limit reached");
// Wait for either a new connection to be established (if you called makeBackgroundConnection) or for
// an existing connection to be freed up.
try {
wait();
catch(InterruptedException ie)
log.write(ie.getMessage());
// Someone freed up a connection, so try again.
return(getConnection());
}//EO main if-else
return null;
}//EO getconnection method
// You can't just make a new connection in the foreground
// when none are available, since this can take several
// seconds with a slow network connection. Instead,
// start a thread that establishes a new connection,
// then wait. You get woken up either when the new connection
// is established or if someone finishes with an existing
// connection.
private void makeBackgroundConnection() {
connectionPending = true;
try {
Thread connectThread = new Thread(this);
connectThread.start();
} catch(OutOfMemoryError oome) {
// Give up on new connection
log.write(oome.getMessage());
public void run() {
try {
Connection connection = makeNewConnection();
synchronized(this) {
availableConnections.addElement(connection);
connectionPending = false;
notifyAll();
} catch(Exception e) { // SQLException or OutOfMemory
// Give up on new connection and wait for existing one free up.
log.write(e.getMessage());
// This explicitly makes a new connection. Called in
// the foreground when initializing the ConnectionPool,
// and called in the background when running.
private Connection makeNewConnection()
//log.write("make new connection with "+url+" "+username+" "+password +" and driver= "+driver);
Connection connection=null;
try
// Load database driver if not already loaded
//Class.forName(driver);
DriverManager.registerDriver(new OracleDriver());
// Establish network connection to database
connection = DriverManager.getConnection(url, username, password);
if( connection.isClosed() )
log.write("ooooooops no connection");
else
log.write("yahoooo get connection");
catch(Exception e)
log.write(e.getMessage());
return(connection);
public synchronized void free(Connection connection) {
busyConnections.removeElement(connection);
availableConnections.addElement(connection);
// Wake up threads that are waiting for a connection
notifyAll();
public synchronized int totalConnections() {
return(availableConnections.size() + busyConnections.size());
/** Close all the connections. Use with caution:
* be sure no connections are in use before
* calling. Note that you are not <I>required</I> to
* call this when done with a ConnectionPool, since
* connections are guaranteed to be closed when
* garbage collected. But this method gives more control
* regarding when the connections are closed.
public synchronized void closeAllConnections() {
closeConnections(availableConnections);
availableConnections = new Vector();
closeConnections(busyConnections);
busyConnections = new Vector();
private void closeConnections(Vector connections) {
try {
for(int i=0; i<connections.size(); i++) {
Connection connection =
(Connection)connections.elementAt(i);
if (!connection.isClosed()) {
connection.close();
} catch(SQLException sqle) {
// Ignore errors; garbage collect anyhow
log.write(sqle.getMessage());
}i get this code from internet, in which it also mention that use following code
public class BookPool extends ConnectionPool {
private static BookPool pool = null;
private BookPool(...) {
super(...); // Call parent constructor
public static synchronized BookPool getInstance() {
if (pool == null) {
pool = new BookPool(...);
return(pool);
}if some one want to use it for whole application then use connection pool by BookPool,
now main point is i m not getting the BookPool class could some one explain it to me???
and second by using it can i connect to different users of DB at a time, if cant then how i can.
its good if some one explain it by little code.
thxxxxxxxxxxxxxxxxxxIf this is a real, serious application and not just for practice, then why are you trying to write your own connection pool implementation?
You'd better use Jakarta's Commons Pool and Commons DBCP, which are widely used, well tested implementations of connection pools.
If this is a web application running in a J2EE container, you'd normally configure the connection pool in the container. The container will register the pool in JNDI and you'd look it up in JNDI from your application.
Here's some documentation on how to do that in Tomcat 5.5: JNDI Datasource HOW-TO
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