Number of instances of SingleThreaded servlet

Does anybody know how many instances of a SingleThreaded servlet does WL
          server create per request? Does it do it in say pool of 5 and then if all 5
          are used and a new request comes - does it create another 5 (or so many)? I
          could't find info on this in WL doc.
          Thanks,
          Natasha

Here is my understanding:
          The pool is incremental one by one when all instances of the pool are used.
          Say, if all 5 are used and a new request comes, WL will create a new
          instance for this request, and return this instance to pool later, the size
          of the pool is 6 at this time.
          Cheers - Wei
          Natasha Stavisky <[email protected]> wrote in message
          news:[email protected]..
          > Does anybody know how many instances of a SingleThreaded servlet does WL
          > server create per request? Does it do it in say pool of 5 and then if all
          5
          > are used and a new request comes - does it create another 5 (or so many)?
          I
          > could't find info on this in WL doc.
          >
          > Thanks,
          > Natasha
          >
          >

Similar Messages

ABAP-OO: Create any number of instances

Hello,
please, look at this simple scenario:
DATA:
my_class type ref to zcl_xyz.
create object my_class.
In that case I have just created one instance. Now I need a mechanism to create and identify any number of instance of the type zcl_xyz. <b>That means, I dont know exactly, if I need 5 or 200 instances.</b> Any feasible idea, how to handle that?
Thanks and regards.

Hi,
Declare one static attribute in the class.
Here is the sample code to trap the number of instance created for an object type.
CLASS C1 DEFINITION.
PUBLIC SECTION.
    CLASS-DATA CREATE_COUNT TYPE I.
    METHODS CONSTRUCTOR.
ENDCLASS.
DATA: O1 TYPE REF TO C1,
      O2 LIKE O1,
      O3 LIKE O1.
CREATE OBJECT: O1,
               O2,
               O3.
WRITE: 'Number of created objects:', C1=>CREATE_COUNT.
CLASS C1 IMPLEMENTATION.
METHOD CONSTRUCTOR.
    CREATE_COUNT = CREATE_COUNT + 1.
ENDMETHOD.
ENDCLASS.
Hope this hint helps you.

How count the total number of instances ?

I have 2 scenarios :-
1. How to get the total number of instances of the node in a BO?
eg :
businessobject BO1   {
element BO_ID;
                   node NODE1 [0..n]
                     element Node_ID;
                     element Status ;
                     element value:
I want to get total number of the NODES instances in the particular instance of the BO1.   !!!?????
2. I want to make some calculations based on the attributes of the NODE1 , in the   BeforeSave .absl of the Business Object BO1.
eg:
something like this :-
In BeforeSave of BO1.absl -
for ( all the instances in NODE1 )
{   if (NODE1.status == true)
             sum = sum + NODE1.value
Please help !!!!

Your approach is correct.
You can use a standard Query or create your own Query to run through Datainstances.
Documentation with examples for Queries in ABSL see here: https://my020062.sapbydesign.com/sap/ap/ui/repository/SAP_BYD_WEKTRA/CP/sapLSUIContentPlayerTestPage.html?manifest=067D03A7602B1D490899DF46B5082089&COMPONENT=A1S_PDI&RELEASE=260&LANGUAGE=en&REGION=&INDUSTRY=&TASK=CR_VIEW&sap-language=EN
Looking / Clincking for "SAP Business ByDesign Scripting Language" and "Syntax for Implementation of Actions and Events" and "Query"

The difference of minor number and instance number

I study how to develop device drivers. I am beginner.
I'm confusing the differece of minor number and instance number
what is the exact difference of them???

Hi,
I guess a good example would be a disk. Each disk you have would be a different instance. To use a disk it is divided into slices, each of which has a different minor number.
Your device driver needs to map the minor number to the correct instance of the device. How you do this is completely up to you, so to start you could map them one to one.
Hope that helps.
Ralph
SUN DTS

Updating the BPM workspace view based on the number of instances in view

Hi All,
We are using ALBPM 6.0.5 enterprise with Weblogic 10 server. We have a requirement to update dynamically the view name in the left side panel in BPM workspace. Based on the number of instances created, the view(view name ABC) should carry something like "ABC(2)". 2 being the number of instances in the view. It's more like a mailbox client InBox. Depending on the number of mails, the Inbox changes the number highlighting new mails.
I've tried using the Workspace API to update the cusom decorator class getRow() method to update the view CSS property. But it doesn't seem to work. All I'm able to do with the decorator class is to update the propeties of instances, but not other panels?
Is there any API to control the panel properties in BPM workspace?
By the way, I'm using the standard workspace without any changes.
Any pointer will be much appreciated.
Cheers.

Yes, I'm hoping to fill in DataGridA with all records from dc where dc["ENTITY_ID"] = dr["ENTITY_ID"]
I tried your statement and received the following errors:
Error 1
The left-hand side of an assignment must be a variable, property or indexer
C:\ISMG_7210\MedicalSequenceDataAnalysisProject\OTCS_Algorithm\OTCS_Algorithm\Form1.cs
87 71
OTCS_Algorithm
Error 2
Cannot implicitly convert type 'object' to 'int'. An explicit conversion exists (are you missing a cast?)
C:\ISMG_7210\MedicalSequenceDataAnalysisProject\OTCS_Algorithm\OTCS_Algorithm\Form1.cs
87 99
OTCS_Algorithm
Thank you for your help.
Joel Fredrickson
Yes, please follow example provided by Kristin, the error is because of missing comparison operator ==, and that the dr["ENTITY_ID"] is of type object that needs to be converted to int. I've updated my code, if you have Entity_ID in your DB as
double use Convert.ToDouble instead.
Fouad Roumieh

Why doesn't a search show the number of instances found?

I'm shocked that Internet Explorer does this but Firefox doesn't -- when I do a search on a page (ctrl-F), why doesn't it show the number of instances found on that page? See IE8 for an example. This should be built-in and not require an add-on, but I'll take it any way I can.

*Find In Numbers: https://addons.mozilla.org/firefox/addon/6738

How to control the number of instances of an object ?

Hi all,
Can anybody answer, How to control the number of instances of an object being created?
suppose at any point of time, if i would like to have 5 instances at the maximum, how can i disable the further requests?
Thanks in advance
Pradi

write a factory method that controls the number of instances for you:
import java.util.List;
import java.util.Arrays;
public class Bar
   private static final int MAX_BARS = 5;
   private static int numBars = 0;
   private int id;
   public static void main(String [] args)
      try
         int numBars = ((args.length > 0) ? Integer.parseInt(args[0]) : MAX_BARS+1);
         Bar [] bars = new Bar[numBars];
         for (int i = 0; i < bars.length; ++i)
            bars[i] = Bar.create();
         System.out.println(Arrays.asList(bars));
      catch (Exception e)
         e.printStackTrace();
   private Bar() { this.id = numBars++; }
   public String toString() { return "I am bar number " + this.id; }
   public static Bar create()
      Bar nextBar = null;
      if (numBars < MAX_BARS)
         nextBar = new Bar();
      return nextBar;
}%

The maximum number of instances has been exceeded

Hi,
I my PROD environment i am getting this type of exception.
Instance Cache: Opening the cache for process '/ProcessName#Default-1.0'. The maximum number of instances has been exceeded.
any suggestion ?
Thanks,
Brijesh Kumar Singh

Hi Brijesh,
Please post the Complete StackTrace. When are you getting this exception...means which operation are u performing?
Are u in a Clustered Environment?
Which version of WLS are u using?
by anychance Are you getting the following Oracle Error Code in your Server Logs anywhere: ORA-00020 ?
Thanks
Jay SenSharma
http://jaysensharma.wordpress.com (WebLogic Wonders Are Here)

Number of instances

does any one know a simple way to return the number of
instances or the number of synchronized objects in a
fms application??
thank you in advance.

does any one know a simple way to return the number of
instances or the number of synchronized objects in a
fms application??
thank you in advance.

Number of Instances of any Object in JVM

Hello Guys, Is there any way to know number of instances for any perticular class in JVM. For example i want to know how many instance of calss "Vector" are there in JVM. Can we write any program which take class name as parameter and tells the number of instances ? is there any thing readly available in some place or if some of you guys might already written.
Please let me know, thanks.

In the destoryMine set the object to null and
decrease the minecount by one.I follow everything you say but this. How do you "set
the object to null"? Could you provide some Java
source code as an example?I guess I don't see the problem you do. Assuming Mine has a single constructor taking a String parameter, what is wrong with this:
public class MineFactory {
    private static int counter = 0;
    public static Mine createMine(String value) {
        counter++;
        return new Mine(value);
    public static void destroyMine(Mine mine) {
        mine = null;
        counter--;
    public int getMineCount() {
        return counter;
}? The line         mine = null; is not a problem, is it?
-- Scott

Instance variables in Servlets.

Hi
Is it a good practice to use instance variable in servlet.
Please refer code snippet below.
public class ExcelAction extends HttpServlet {
private int var1 =0;
doGet () {
var1++;
fun1();
fun1 (){
var1++;
}Like in above code I have used an instance variable var1 because I wish the same to be accessible in all servlet functions.
I guess it is not a good practice, as different requests to this servlet at same time will result in multiple threads of this servlet. Which will make the state of var1 unsafe.
If this is correct then what are the alternates if I wish to share variables between functions in a servlet.
Thanks

money321 wrote:
Because in beginning I was not sure that Servlets instances are also actually threads.They are not not threads. Each call to doGet(), doPost() etc is called in a Thread and since there can be many simultaneous calls each having it's own thread a Servlet has to be thread safe.
My other question was specific to threads as I was trying to implement threads.Why?
>
But in this one I rather used servlets.
But apologies, as instance of servlet are also threads.As I said, they are not threads.
>
But still one last doubt.
Sabre if you could please clarify the same as well :How about you do some reading [http://java.sun.com/developer/onlineTraining/Servlets/Fundamentals/|http://java.sun.com/developer/onlineTraining/Servlets/Fundamentals/] and use Google.
>
in your option 2 and three I will have to pass request object to function fun().No. You will need access to the request object for 2 and the servlet context for 3. You need to pass something
If i am correct on this then is this too a better approach ?My preferred approach is 1 since it makes much of your code testable outside of a Servlet.

Instance of each servlet

I have a web page ,JSP, which calls different servlets for DB stuff. My question is this : will there be a new instance of each servlet for each user when connecting to the the website or should I do something about it.

hello again
could you also tell me whats the correct way to do
this. As far as I know I can mix the Model and
controller inside a servlet, but with this fixture
everything will go nuts! do you think I should use
the servlet as a controller and a javabean as a
model. OR something else.
Thanks again for the help.I was in your situation 1 or 2 years ago, and I would just like to share what I've found and try to explain in an easy manner what technologies you could use, and how they work.
The problem with servlets is that each connection to the same servlet will create a new thread. This is different from the classical CGI approach, where each connection starts a new process.
The consequence is that you end up coding in a multithreaded environment, with all the hassles with deadlocks, race conditions, problems with shared variables (as mentioned in previous posts) etc.. These problems are difficult to solve, and time consuming. The reason for the multithreaded solution is that it provides a significant performance boost over the "new process" solution. However, it is obvious that a developer doesn't want to worry about multithreading when he/she has a deadline to comply with ;) So, you ask, should I just scrap Servlets or is there a better solution?
Well, to get rid of this problem for developers, Sun proposed a standard to reduce the complexity of web development. It's called Java EE (http://java.sun.com/javaee/5/docs/tutorial/doc/)
By maintaining persistent (long lasting) state in a database, and temporary state (session state etc) in a controlled manner, Java EE proposed a way of getting rid of the classical problems in Java web development, and also added several cool new features.
When using Java EE, you have a special type of beans to save persistent state, they're called entity beans. If you have defined a entity bean (wrote an ordinary java class, and supplied some settings), you can create a new entity bean, set its properties, and tell the Java EE system to save it to your database. You can also search among saved ones (something like "select p from Person as p where p.username='foo' and p.cousin.name='bar'"), let them reference each other and all sorts of neat things.
There are also beans which are supposed to perform logic using your entity beans, and they're called session beans. They have methods containing your business logic, namely methods like 'getLatestForumPost(), or 'createUser(String name)'...
The session beans can also save temporary state. If they do so, they're called "stateful session beans". The state they keep is stored like ordinary class attributes, but Java EE makes sure that you won't get thread problems (even though there still are multiple threads). For example, you can use this state to keep track of items in a shopping cart (based on the current user). If several users want their own cart, Java EE just creates a new stateful session bean for each user, you don't have to modify your bean in any way!
Until now, I've used the word "Java EE", as if it's an actual product, but as I mentioned, it's just a standard. Since it is just a standard, telling how things should work, there are several companies that have made solutions (programs) that actually make things work like this. An application that "make thing work" is called a Java EE Application Server. You need to start the application server in order to run you own Java EE program (you program will be almost like a plugin to the server, or you could say that you program runs within the server). Behind the scenes, the application server usually uses ordinary Servlets to process each request, but it handles all the multithread problems (and others) for you. If you for some reason would like to, you can always gain finer control by using Servlets directly.
When a user connects to your computer, the server can automaticly identify the user, give him some cookies identifying him, ask for login (if you told the server to do so), and then hand over control to you, telling you this persons login name, what he asked to do, amongst other things, which saves you a lot of hassle. You can alway tell the server how to behave in different situations (for example wich pages or requests that require login etc), by writing some xml config files for each application.
The application server also lets you send mails from your session beans, send messages between computers, run your application on clusters, parse XML and several of other neat things. It's a dream for a web application developer.
I hope this will inspire you to have a look at these things, because it really simplifies things, and if you learn it correctly, you can also make some serious money as a Java EE developer ;)
The only downside is that it seems pretty complex in the beginning, and that it's pretty hard to understand all the vague definitions in the docs etc... I would recommend that you download the Application server from Sun (http://www.sun.com/software/products/appsrvr/index.xml), read the tutorial at http://java.sun.com/javaee/5/docs/tutorial/doc/ and start to write some own programs.
Don't be passive, just try everything out and you'll figure out that it's less complicated than it seems at the first glance.
I really hope that this helps!, and sorry for my bad English.
Best regards
/Alexander T

Maximum number of instances that can be created on an oracle server ?

Hello all....
Can you tell me what is the maximum number of instances that can be created on an oracle server ?
thanks and regards
vinay raj

vinay raj wrote:
Hello all....
Can you tell me what is the maximum number of instances that can be created on an oracle server ?
thanks and regards
vinay raj
The answer would be that as many as the server's ram would hold up . There is no limitation otherwise as such. How many maximum you have created so far?
Aman....

Number of Instances 2 or 4?

Hi, I just got the 2.66GHz Quad-Core Intel Xeon "Nehalem" processor MacPro. Do I select the Number of Instances to 2 or 4? Thanks

I've noticed that all of my processors are active during processing, no matter what the number of Qmaster instances are. The instances are not the cores that are in use, but rather how many parallel process are running.
Example:
If you have a 4 core Mac and set it to 2 instances, then you will see in the batch monitor window that two process are running, but that all cores are processing the information. You can see this if you have a system utility like menu meters running, which shows how your cores are being used.
The advantage here is that the more processes that are running in parallel, more of the head room for each processor is consumed, (till it reaches 100% for each processor.) Qmaster will also split up a single file into many mini files, so that different parts of the same file can be worked on in parallel, so that the single file will finish sooner, than when it is encoded from start to finish as a single encode, (like when you select "This computer" under the submit button of compressor, rather than using a cluster.
I have two 4 core Mac's one is a G5/quad and the other is an Intel 3.0Ghz 4 core. I run both in Qmaster with 3 instances, which puts it just under 100% of all cores headroom being consumed and works just fine, finishing project very quickly.

MDB and number of instances

Hello,
How could I setup the number of instances limitation for a MDB ? I use for deploy Sun Application Server 8.0
Thank you for feedbacks

Hi Gazi,
You can control this using the max-pool-size element of bean-pool in sun-ejb-jar.xml. See the sun-ejb-jar dtds in lib/dtds for more info. This sets the value on a per-bean basis. You can also set the default for all message-driven beans in domain.xml.
--ken
Kenneth Saks
J2EE SDK Team
SUN Microsystems

Number of instances of SingleThreaded servlet

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