Multi Threading..on object locking
when a synchronised method of an object is invoked by a thread that object gets locked. can another thread invoke unsynchronized method of the same object? howz it possible..if it is possible..pl give the rationale behind this..
Yes it can. And the reason is part of your homework assignment.
Similar Messages
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Immutable Objects in multi threaded application - how does it works?
Hi
I have this code will work in multithreaded application.
I know that immutable object is thread safe because its state cannot be changed. And if we have volatile reference, if is changed with e.g.
MyImmutableObject state = MyImmutableObject.newInstance(oldState, newArgs); i.e. if a thread wants to update the state it must create new immutable object initializing it with the old state and some new state arguments) and this will be visible to all other threads.
But the question is, if a thread2 starts long operation with the state, in the middle of which thread1 updates the state with new instance, what will happen? Thread2 will use reference to the old object state i.e. it will use inconsistent state? Or thread2 will see the change made by thread1 because the reference to state is volatile, and in this case thread1 can use in the first part of its long operation the old state and in the second part the new state, which is incorrect?
Therad1: Thead2:
State state = cache.get(); //t1
Result result1 = DoSomethingWithState(state); //t1
State state = cache.get(); //t2
->longOperation1(state); //t1
Result result2 = DoSomethingWithState(state); //t2
->longOperation1(state); //t2
->longOperation2(state);//t1
cache.update(result1); //t1
->longOperation2(state);//t2
cache.update(result2);//t2
Result DoSomethingWithState(State state) {
longOperation1(state);
//Imaging Thread1 finish here and update state, when Thread2 is going to execute next method
longOperation2(state);
return result;
class cache {
private volatile State state = State.newInstance(null, null);
cache.update(result) {
this.state = State.newInstance(result.getState, result.getNewFactors);
get(){
return state;
}Please don't cross post
http://stackoverflow.com/questions/6803487/immutable-objects-in-multi-threaded-application-how-does-it-work -
Multi-thread application recompile object with make but runs with old value
Hi. I am working on a simulation in Java, and there is some behavior going on that I cannot understand. Granted, I'm a mechanical engineer, not a CS student (a fact that is probably made obvious by the code I'm posting below). The simulation comprises three parts: a controller, a robot, and a 3-d sensor. Here's the code for the "Simulation" application.
class Simulation {
void go() {
ThreeDSensor sensorRunner = new ThreeDSensor();
VSController controllerRunner = new VSController();
KukaKR15SL robotRunner = new KukaKR15SL();
Thread sensorThread = new Thread(sensorRunner);
Thread controllerThread = new Thread(controllerRunner);
Thread robotThread = new Thread(robotRunner);
sensorThread.start();
try {
Thread.sleep(1000); // Give sensorThread time to start in order to catch first triggers
} catch(InterruptedException ex) {
ex.printStackTrace();
controllerThread.start();
try {
Thread.sleep(1000); // Give controllerThread time to open the socket for communication with robotThread
} catch(InterruptedException ex) {
ex.printStackTrace();
robotThread.start();
public static void main(String[] args) {
Simulation sim = new Simulation();
sim.go();
}I guess the big reason I'm using multi-threading is that once this simulation is working I want to be able to just run VSController alone and have it interface with a robot controller and a PC performing image processing. So with multiple threads I'm sending TCP and UDP messages around just like the final system will.
I have made an object for my VSController that just stores values used by the simulation. That way I could have them all in one place instead of hunting through methods to change them. One example is "double noiseThreshold". Quickly, here is the code for "ControllerSettings.java".
class ControllerSettings {
final double cameraXOffset = 0; // If > 0 then the origin of the camera CS is not on the center line of the lens
final double cameraYOffset = 0; // If > 0 then the origin of the camera CS is not on the center line of the lens
final double cameraZOffset = 700; // The distance that must be kept between the camera and the target
// Error magnitude less than this is disregarded (in centimeters if roundingData else in millimeters)
final double noiseThreshold = 60;
final boolean estimatingEndPoints = false; // If the controller is using two images per cycle then true
final boolean roundingData = false;
final boolean using3DData = true; // How double[] sent from Matlab image processing is used
* If the robot controller uses the output of this controller to command
* motions in cartesian space then true. This is used in two places: 1) initial guess of Jacobian,
* and 2) "commandType" element sent to robot controller.
final boolean useRobotControllerModel = false;
final double thetaBumpValueForEstimationOfJacobian = .1; // Distance each joint is jogged in estimation process
final double bumpDistance = 50; // Distance robot moves each time (magnitude of translation in mm)
final double limitAngular = .5; // Max amout robot joint will be commanded to rotate (in degrees)
}And here is some pertinent code from "VSController.java".
class VSController implements Runnable{
ControllerSettings cSettings; // Stores all the preferences used by the controller
NGN controller; // This is the controller algorithm.
int dof; // The degrees of freedom of the robot being controlled
KukaSendData ksd; // This provides communication to the robot.
protected DatagramSocket socketForVisionSystem = null;
ImageFeaturesData ifd; // This parses and stores data from the image system.
double[] errorVector; // This is what's acted on by the algorithm
PrintWriter errorTrackerOut = null; // For analysis of error vector
public void run() {
VSController vsc = new VSController();
vsc.go();
public void go() {
initWriters();
cSettings = new ControllerSettings();
public boolean isNoise() {
boolean ret = false;
double magnitude = 0;
for (int i = 0; i < errorVector.length; i++) {
magnitude += errorVector[i] * errorVector;
magnitude = Math.sqrt(magnitude);
if (magnitude <= cSettings.noiseThreshold) {
System.out.println("VSController: magnitude (of errorVector) = " + magnitude +
", threshold = " + cSettings.noiseThreshold); // Debug
Now here's my issue: I change the value for "noiseThreshold" in "ControllerSettings.java" then run make from terminal (makefile code posted below) and rerun "Simulation". However, despite my changes to "ControllerSettings.java" the value for "noiseThreshold" is not changed, as evidenced by the output on the terminal screen:VSController: magnitude (of errorVector) = 6.085046125925263, threshold = 10.0 See, that value of 10.0 is what I used to have for noiseThreshold. I do not know why this value does not update even though I save the java file and execute make in between executions of Simulation. I would love it if someone could explain this problem to me.
Here's the contents of makefile.
JFLAGS = -cp ../Jama\-1\.0\.2.jar:../utils/:/usr/share/java/vecmath\-1\.5\.2.jar:.
JC = javac
.SUFFIXES: .java .class
.java.class:
$(JC) $(JFLAGS) $*.java
CLASSES = \
ControllerSettings.java \
ImageFeaturesData.java \
KukaKR15SL.java \
../utils/KukaSendData.java \
NGN.java \
Puma560.java \
Robot.java \
RobotSettings.java \
Simulation.java \
SimulationSettings.java \
SixRRobot.java \
Targets.java \
TargetsSettings.java \
ThreeDData.java \
ThreeDSensor.java \
VSController.java
default: classes
classes: $(CLASSES:.java=.class)
clean:
$(RM) *.classEdited by: raequin on Apr 5, 2010 1:43 PMI saw this explanation about what's causing my problem.
"When the Java compiler sees a reference to a final static primitive or String, it inserts the actual value of that constant into the class that uses it. If you then change the constant value in the defining class but don't recompile the using class, it will continue to use the old value."
I verified that the value updates if I also change something in VSController.java, forcing it to recompile. I think I will solve this problem by just making the variables in ControllerSettings no longer final (and then recompile VSController to make sure it takes effect!). Is there another solution? I saw intern(), but that seems to only apply to Strings.
Thanks. -
Would you give me some information about objective-c multi thread
hello,
I am studing objective-c multi thread, but have not enough information. would you give me some, please? Thanks very much!Have you tried the ADC pages: http://developer.apple.com/macosx/?
Multi-threading can be a complicated business in any programming language, so good luck! -
Would you give me some information about objective-c multi thread please
hello,
I am studing objective-c multi thread, but have not enough information. would you give me some, please? Thanks very much!Hello
You rang at the wrong door.
This forum is dedicated to AppleWorks, not to objective-c
Yvan KOENIG (from FRANCE mercredi 9 août 2006 07:38:25) -
Hi there.
I have a question about when a thread acquires an objects lock.
Just to get some facts straight in my head:
When a thread gets a hold of an objects lock, does it hold onto that
lock even when the thread is moved from a running state back to a runnable
state, say, due to time-slicing?
Thanks and regards.Boeing-737 wrote:
DrLaszloJamf wrote:
Absolutely. For example, a thread can acquire a lock then Thread.sleep for an hour.That isn't the same scenario though, is it?
I thought that when a thread sleeps, it's not runnable until after it wakes up...
Maybe im wrong. Go easy on me!
Edited by: Boeing-737 on Jun 3, 2008 11:45 AMYou're right. I was just stressing that a thread doesn't release a lock easily. -
InfoPath: the multi-threading challenge
Or to be more specific: calling a DataSource from a different thread.
A project I'm working on includes an InfoPath form in which some heavy duty tasks are executed. These tasks can take over 10+ seconds to execute. To avoid the GUI to get stuck during execution, multi-threading is implemented. The problem lies in providing
feedback to the user. Several methods have been used, but all end in the exceptions shown below.
Unlike WinForms and such, InfoPath does not seem to provide a way to invoke the GUI. What we are trying to do is change field values to reflect the status of the process. This is done through the MainDataSource. I've tried several methods to call
this datasource through another thread, like invoking a provided delegate, or execution context. However all these methods have similar results.
When calling a method or property on the datasource the following exception is thrown:
System.InvalidOperationException was unhandled
Message="Operation is not valid due to the current state of the object."
Source="Microsoft.Office.InfoPath.Client.Internal.Host"
StackTrace:
at Microsoft.Office.Interop.InfoPath.SemiTrust.ICLRExtensionsWrapper.IncrementSqmPoint(Int32 idDataPt)
at Microsoft.Office.InfoPath.Internal.DataSourceHost.CreateNavigator()
at Form1.FormCode.ContextCallbackMethod(Object obj) in E:\Projects\InfoPath Multithreading\Source\Form1\FormCode.cs:line 74
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at Form1.FormCode.ThreadMethod(Object myParamsObj) in E:\Projects\InfoPath Multithreading\Source\Form1\FormCode.cs:line 68
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart(Object obj)
This seems to indicate the DataSource is locked for some reason. Even the ReadOnly property can not be read.
When calling the SetValue method on an XPathNavigator provided by a datasource and passed through another thread, the following exception is thrown:
System.AccessViolationException was unhandled
Message="Attempted to read or write protected memory. This is often an indication that other memory is corrupt."
Source="Microsoft.Office.InfoPath.Client.Internal.Host.Interop"
StackTrace:
at Microsoft.MsoOffice.InfoPath.MsxmlInterop.NativeHelpers.SetText(IXMLDOMNode* , Char* )
at Microsoft.MsoOffice.InfoPath.MsxmlInterop.MsxmlNodeImpl.set_Text(String strText)
at Microsoft.Office.InfoPath.MsxmlNavigator.SetValue(String value)
at Form1.FormCode.DelegateMethod(XPathNavigator nav) in E:\Projects\InfoPath Multithreading\Source\Form1\FormCode.cs:line 81
at Form1.FormCode.ThreadMethod(Object myParamsObj) in E:\Projects\InfoPath Multithreading\Source\Form1\FormCode.cs:line 70
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart(Object obj)
I have searched through the internet but am unable to find any useful information about this subject. There are only a few weeks remaining before the deadline. A work-around has been implemented, but since it requires additional active user interaction
it is far from ideal. I hope you can help me in finding a solution.For anyone who is still interested all this time later....
I wouldn't use a Dispatcher in InfoPath simply because InfoPath requires .Net 2.0 only and Dispatcher was not added until .Net 3.0 which means you would have to enforce installation of .Net 3.0 yourself.
There is an easy alternative which is SynchronizationContext (more specifically a WindowsFormsSynchronizationContext).
Also I suggest you do not use ThreadStart but rather use one of the more modern and well known threading paradigms. A good alternative is a BackgroundWorker.
e.g.
private BackgroundWorker _Worker;
public void InternalStartup()
InitializeWorker();
((ButtonEvent)EventManager.ControlEvents["Button"]).Clicked += new ClickedEventHandler(ButtonClick);
public void InitializeWorker()
_Worker = new BackgroundWorker();
_Worker.WorkerReportsProgress = true;
_Rorker.WorkerSupportsCancellation = true;
_Worker.DoWork += new DoWorkEventHandler(_Worker_DoWork);
_Worker.ProgressChanged += new ProgressChangedEventHandler(_Worker_ProgressChanged);
_Worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(_Worker_RunWorkerCompleted);
public void ButtonClick(object sender, ClickedEventArgs e)
if (_Worker.IsBusy)
_Worker.CancelAsync();
else
// Very important to include this line!
AsyncOperationManager.SynchronizationContext = new WindowsFormsSynchronizationContext();
_Worker.RunWorkerAsync();
void _Worker_DoWork(object sender, DoWorkEventArgs e)
// Do stuff in another thread and report back to the UI thread.
object state;
int percentage = 0;
_Worker.ReportProgress(percentage, state).
public void _Worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
// This is called on the thread that started the worker.
// In this case the UI thread which means it is safe to use the MainDataSource.
CreateNavigator().SelectSingleNode("my:Main/my:Progress", NamespaceManager).SetValue(e.ProgressPercentage);
void _Worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
// Do anything you want to do on completion here.
One thing of note is that the SynchronizationContext in InfoPath for some reason or other always seems to be Null. The result is that when you call RunWorkerAsync() it captures the current synchronization context (null) which means the default is used and
a ProgressChanged is called on a new thread each time. To prevent this we need to manually set the context before calling RunWorkerAsync() which is done using the AsyncOperationManager. -
When implementing the Singleton design pattern in Java, we must use keyword <b>synchronized</b> with <b>getInstance()</b> method to ensure multi-threading safety, so that we can get the one and only instance.
What shall I do in ABAP? or just leave it alone? Would you help me find a example?
thanks and regards,
Davin,WANGHi Davin,
I do not understand fully what you are going to do in ABAP terms so I hope my comment will be of any value.
Multithreading may be achieved in ABAB by calling a function with the addition STARTING NEW TASK IN GROUP.... See my sample program for <a href="https://wiki.sdn.sap.com/wiki/display/Snippets/Easilyimplementparallelprocessinginonlineandbatchprocessing">Easily implement parallel processing in online and batch processing</a>
The second question may be solved by help of SAP lock concept. This is used primarily to secure a consistent database by not allowing two processes to change data at the same time. Chose a lock object of your choice and set at start of first instance. At end, remove the lock. Before creating the second instance, try so set the same lock. If you get a foreign lock error, you know the process is running.
See documentation on lock objects on how to lock/unlock.
Regards,
Clemens
Hope your internet connection is broken no longer so you can read this. -
Hi all,
What is multi threading? How to implement multi threading in ABAP?
Regards,
BryanHi
How the vision connector framework works
The connector interacts with an SAP application using connector modules. The connector modules make calls to SAP's Native Interfaces and pass data (business object or event data) to and from an SAP application. The connector's flexible design enables different modules to be used for different tasks such as initializing the connector with the SAP application or passing business object data.
Communication between the connector and an SAP application
The connector uses SAP's Remote Function Call (RFC) library to communicate with an SAP application. SAP's RFC API allows external programs to call ABAP function modules within an SAP application.
Processing business objects
The connector is metadata driven. Metadata, in the WebSphere business integration system, is application-specific data that is stored in business objects and that assists a connector module in its interaction with the application. A metadata-driven connector module handles each business object that it supports based on metadata encoded in the business object definition rather than on instructions hard-coded in the connector module.
Business object metadata includes the structure of a business object, the settings of its attribute properties, and the content of its application-specific information. Because connector modules are metadata driven, they can handle new or modified business objects without requiring modifications to the connector-module code.
The vision connector framework uses the value of the verb application-specific information in the top-level business object to call the appropriate connector module to process the business object. The verb application-specific information provides the classname of the connector module.
The verb application-specific information of most top-level business objects must identify the classname of the connector module. The syntax of this verb application-specific information is:
AppSpecificInfo = PartialPackageName.ClassName,
For example,
AppSpecificInfo = sap.sapextensionmodule.VSapBOHandler,
In this example, sap.sapextensionmodule is the partial package name, and VSapBOHandler is the classname. The full package name includes the com.crossworlds.connectors prefix, which the WebSphere business integration system adds to the name automatically. In other words, the full text of the example is:
com.crossworlds.connectors.sap.sapextensionmodule.VSapBOHandler
Note:
The verb application-specific information of most top-level business objects must use a comma (,) delimiter after the connector classname. However, the Server verb, which is used by the RFC Server Module, is delimited instead by a semi-colon (;). For information about the Server verb, see How the RFC Server Module works and Supported verbs.
You need not specify the package name and classname for the verb application-specific information if the business object is used:
by the ALE Module to process application events; however, when you use the ALE Module to process service call requests, you must specify the package name and classname
by the ABAP Extension Module, which uses the default business object handler (sap.sapextensionmodule.VSapBOHandler)
Important:
Customer-generated connector modules that process business objects for the RFC Server Module must specify a full package name, which must begin with bapi. For example, bapi.client.Bapi_customer_getdetail2. The full package name in this example is bapi.client, and the classname is Bapi_customer_getdetail2.
Most business object processing is specific to each connector module. By default the connector uses the ABAP Extension Module. For more information on business object processing for the ABAP Extension Module, see Installing and customizing the ABAP Extension Module and Business object data routing to ABAP handlers. .
For more information on specifying verb application-specific information for the ALE Module, see Event processing and Processing multiple IDocs with a wrapper business object.
Processing multiple concurrent interactions
The Adapter Framework can create separate threads for processing an application event and a business object request. When processing multiple requests from the integration broker, it can create multiple threads to handle multiple business object requests. For example, when InterChange Server is the integration broker, the connector can receive multiple business object requests from multiple collaborations or from a multi-threaded collaboration.
Figure 4 illustrates the multi-threading architecture.
Figure 4. Multi-Threading Architecture of the Connector for SAP
Event processing
The connector performs the following steps when handling a poll call:
The Adapter Framework creates a single dedicated thread to handle poll calls. This thread calls the pollForEvents() method of the vision connector framework at the frequency specified in the PollFrequency configuration property.
The thread polls SAP, which uses a dialog process to locate and return the event.
Note:
If the connector's MaxNumberOfConnections configuration property evaluates to a number greater than 1, the vision connector framework dedicates a connection to SAP for polling. If MaxNumberOfConnections evaluates to 1, event and service-call request processing share a single connection to SAP.
The polling thread dies only when the connector shuts down.
Note:
Because the RFC Server connector agent pushes events out of SAP instead of polling for events, it spawns its own threads instead of using threads created by the connector framework. Because the ALE connector agent uses the RFC Server connector agent to access events, it also spawns its own threads instead of using threads created by the connector framework when it processes events.
Request processing
Independently of polling, the Adapter Framework can create multiple request-processing threads, one for each request business object. Each request thread instantiates the appropriate business object handler.
For example, when processing business object requests from InterChange Server, the number and type of business object handlers depends on the number and type of the collaborations sending the requests:
If multiple collaborations send business objects, each request thread instantiates a business object handler of the appropriate type.
If a multi-threaded collaboration sends multiple business objects of the same type, the request threads instantiate an equal number of business object handlers of that type.
If the connector's MaxNumberOfConnections configuration property evaluates to a number greater than 1, the vision connector framework dedicates one connection to SAP for polling and allocates the remaining connections to a pool used only for request processing.
As illustrated in Figure 4, the connector performs the following steps when handling a business object request:
The Adapter Framework creates a separate thread for each business object request. Each thread calls the doVerbFor() method of the Vision business object handler.
If the connector's MaxNumberOfConnections configuration property evaluates to a number greater than 1, the Vision business object handler checks the vision connector framework's connection pool to determine if a connection handle is available.
If the handle is available, the thread sends the request to SAP, which uses a dialog process to handle the request.
If the handle is not available, the thread waits until one becomes available. Thread sequencing determines the order in which each business object handler thread claims or waits for an available connection handle.
If the connector's MaxNumberOfConnections configuration property evaluates to 1, the Vision business object handler shares a connection with event processing.
SAP releases the dialog process after it completes processing and sends a return code.
The connector releases the connection handle after it receives the return code from SAP.
Setting the number of available connections
Use the MaxNumberOfConnections configuration property to specify the maximum number of connection handles available. The number of connections cannot exceed the number of dialog processes.
SAP locks the dialog process while processing an interaction, releasing it only when the interaction completes. Therefore, multiple concurrent requests lock an equal number of dialog processes until processing finishes.
Important:
Before setting a value for MaxNumberOfConnections, contact your SAP BASIS administrator to determine an appropriate value to maximize throughput without negatively affecting performance on the application server.
Support for multiple connections
By default the connector supports multiple-threads.
<b>
REWARD IF USEFULL</b> -
Multiple Containers read/write access in multi-threaded environment
I'm been reading the Berkeley DB XML Transaction Processing document and have a few questions. I have a multi-threaded environment (not multi-process).
1) In the "Summary and Examples" section, there is an example of several worker threads that perform many writes to a shared container. The one container is passed to all the worker threads, rather them having their own instance of the container. In my application, I could potentially have multiple worker threads acting on the same container, is it better to provide some type of connection pool, so each thread has access to the same container? Is their a problem with each thread creating a new instance of the container and writing to that? Is their pros and cons to each approach?
2) In some specific web applications, they only require read-access and have no intention of writing to the database. If the environment was created with transactions, can these applications open the environment in read-only mode, so as to not suffer the performance penalty of using transactions? Or do they still require transaction support since other threads in other applications might be writing to it. Is it better in this case to
3) Is there any decent connection pooling framework that work well with BDB XML? If transactions are involved, it seems pretty important to always close the container once you are finished with it, which kind of defeats the purpose of pooling. I see a container somewhat analogous to a JDBC transaction, where in connection pooling these transactions remain open, but in BDB XML, it doesn't seem like this is good practice. So clarification here would be appreciated.
Thanks in advance...
ChrisChris,
I'd be careful about trying to draw too many analogies with other sorts of systems. In many ways BDB XML is simpler -- it's just a library, no server process.
An open container is analogous to an open file handle/descriptor in your operating system. It can safely be shared by all threads within a given process. In fact, you should not create more than one -- while that works, it can just be confusing, and a source of errors (for example, if you use a different path to open the container each time, you'll have problems). So by all means share them. Most Java applications just point them in a class that is accessible to all threads.
Other objects that can, and should be shared among threads include:
Environment
XmlManager
XmlQueryExpression
Most others should not. You also mention closing your containers -- there is no reason to close your active container objects until your application needs to shut down. A long-running application will want to use db_checkpoint (or equivalent) to ensure that modified pages are flushed from the transaction log to the database files, but that's about it.
As for concurrency, you obviously need transactions for concurrent write operations. If you want concurrent read access to the same containers, they should use transactions as well. Even if you don't explicitly use transactions, locks are always taken on pages in transactional containers. You cannot open the same container transactionally and not transactionally at the same time -- bad things could happen.
Depending on your performance needs, you could using snapshot concurrency, and see how it works for you. While locking does incur some overhead, it may be acceptable.
You mention creating your own "snapshot" of a container and running read-only on that copy. That's possible to do, but you have to be careful of how you create the snapshot (following hot backup procedures). Also, if you intend to open that "new" container in the same environment or application as the old one, you need to run a program on it to change its internal identification so Berkeley DB won't think it's the same file. That is, you can't just copy a container file to a new name and just open it like it's a new container if it's still in the vicinity of the original. See the -r option for the db_load program.
Now that you are probably really confused, good luck!
Regards,
George -
SSRS - Is there a multi thread safe way of displaying information from a DataSet in a Report Header?
In order to dynamically display data in the Report Header based in the current record of the Dataset, we started using Shared Variables, we initially used ReportItems!SomeTextbox.Value, but we noticed that when SomeTextbox was not rendered in the body
(usually because a comment section grow to occupy most of the page if not more than one page), then the ReportItem printed a blank/null value.
So, a method was defined in the Code section of the report that would set the value to the shared variable:
public shared Params as String
public shared Function SetValues(Param as String ) as String
Params = Param
Return Params
End Function
Which would be called in the detail section of the tablix, then in the header a textbox would hold the following expression:
=Code.Params
This worked beautifully since, it now didn't mattered that the body section didn't had the SetValues call, the variable persited and the Header displayed the correct value. Our problem now is that when the report is being called in different threads with
different data, the variable being shared/static gets modified by all the reports being run at the same time.
So far I've tried several things:
- The variables need to be shared, otherwise the value set in the Body can't be seen by the header.
- Using Hashtables behaves exactly like the ReportItem option.
- Using a C# DLL with non static variables to take care of this, didn't work because apparently when the DLL is being called by the Body generates a different instance of the DLL than when it's called from the header.
So is there a way to deal with this issue in a multi thread safe way?
Thanks in advance!
Hi Angel,
Per my understanding that you want to dynamic display the group data in the report header, you have set page break based on the group, so when click to the next page, the report hearder will change according to the value in the group, when you are using
the shared variables you got the multiple thread safe problem, right?
I have tested on my local environment and can reproduce the issue, according to the multiple safe problem the better way is to use the harshtable behaves in the custom code, you have mentioned that you have tryied touse the harshtable but finally got
the same result as using the ReportItem!TextBox.Value, the problem can be cuased by the logic of the code that not works fine.
Please reference to the custom code below which works fine and can get all the expect value display on every page:
Shared ht As System.Collections.Hashtable = New System.Collections.Hashtable
Public Function SetGroupHeader( ByVal group As Object _
,ByRef groupName As String _
,ByRef userID As String) As String
Dim key As String = groupName & userID
If Not group Is Nothing Then
Dim g As String = CType(group, String)
If Not (ht.ContainsKey(key)) Then
' must be the first pass so set the current group to group
ht.Add(key, g)
Else
If Not (ht(key).Equals(g)) Then
ht(key) = g
End If
End If
End If
Return ht(key)
End Function
Using this exprssion in the textbox of the reportheader:
=Code.SetGroupHeader(ReportItems!Language.Value,"GroupName", User!UserID)
Links belowe about the hashtable and the mutiple threads safe problem for your reference:
http://stackoverflow.com/questions/2067537/ssrs-code-shared-variables-and-simultaneous-report-execution
http://sqlserverbiblog.wordpress.com/2011/10/10/using-custom-code-functions-in-reporting-services-reports/
If you still have any problem, please feel free to ask.
Regards
Vicky Liu -
How to write a multi threaded Cache Event Listener
I have a distributed data cache called tokenCache for my application. I have also added a mapListener to this cache to listen to a particular kind of events.
tokenCache.addMapListener((MapListener) new TokenCacheListenerBean(), new MapEventFilter(tokenFilter), false);
So bascially everytime a token (The domain object of this cache) is updated the entryUpdated() method in my EJB TokenCacheListenerBean is invoked.
The issue I have though is that, from what I observe on running my code is that the Cache Listener is single threaded. So if two Token Objects on my tokenCache are updated,
lets say Token Object A and Token Object B one after the other, the entryUpdated() method in my EJB is invoked for Token Object A and once the invocation is complete
then the entryUpdated() method is invoked again for Token Object B(). At a given point of time there is only one instance of TokenCacheListenerBean EJB. Is there a way to
make this happen in multi-threaded manner ?
Is there a configuration setting somewhere which allows multiple CacheListeners to be instantiated at a given point of time ?
TokenCacheListenerBean EJB_
package oracle.communications.activation.asap.ace;
import java.util.Iterator;
import java.util.Set;
import java.util.logging.Logger;
import javax.ejb.Stateless;
import com.tangosol.net.NamedCache;
import com.tangosol.util.MapEvent;
import com.tangosol.util.MapListener;
import com.tangosol.util.ValueUpdater;
import com.tangosol.util.extractor.PofExtractor;
import com.tangosol.util.extractor.PofUpdater;
import com.tangosol.util.filter.EqualsFilter;
import com.tangosol.util.filter.LikeFilter;
import com.tangosol.util.filter.LimitFilter;
import com.tangosol.util.processor.UpdaterProcessor;
* Session Bean implementation class TokenCacheListenerBean
@Stateless
public class TokenCacheListenerBean implements TokenCacheListenerBeanRemote, TokenCacheListenerBeanLocal, MapListener {
NamedCache asdlCache;
NamedCache tokenCache;
private final int PAGE_SIZE = 1;
private static Logger logger = Logger.getLogger(ConnectionManager.class.getName());;
* An instance of the JCAModeler EJB, represents the JCA-JNEP
JCAModeler jcaBean;
* Default constructor.
public TokenCacheListenerBean() {
// TODO Auto-generated constructor stub
public void entryDeleted(MapEvent Event) {
public void entryInserted(MapEvent Event) {
public void entryUpdated(MapEvent Event) {
Token newToken = (Token) Event.getNewValue();
Token oldToken = (Token) Event.getOldValue();
if ((oldToken.getState() == Token.TOKEN_RESERVED)
&& (newToken.getState()== Token.TOKEN_AVAILABLE)) {
String networkID = newToken.getNeID();
asdlCache = AceCacheFactory.getCache("asdlCache");
tokenCache = AceCacheFactory.getCache("tokenCache");
EqualsFilter filterNE = new EqualsFilter(new PofExtractor(String.class,Asdl.NETWORKID), networkID);
LimitFilter limitFilter = new LimitFilter(filterNE, PAGE_SIZE);
Set removeASDL = asdlCache.keySet(limitFilter);
Iterator asdlIterator = removeASDL.iterator();
if (asdlIterator.hasNext()) {
logger.info(printASDLCache());
ValueUpdater updater = new PofUpdater(Token.STATE);
System.out.println("Token ID:" + newToken.getTokenID());
UpdaterProcessor updaterProcessor = new UpdaterProcessor(updater, Integer.toString(Token.TOKEN_RESERVED));
tokenCache.invoke(newToken.getTokenID(), updaterProcessor);
jcaBean = new JCAModeler(tokenCache);
Object asdlID = asdlIterator.next();
Asdl provisionAsdl = (Asdl) asdlCache.get(asdlID);
asdlCache.remove(asdlID);
jcaBean.provision(provisionAsdl, newToken.getTokenID());
logger.info(ConnectionManager.printTokenCache());
logger.info(printASDLCache());
}Here is what I am asking!
I have added 2 listeners (Listener A and Listener B) which each listen on for changes made to 2 different token Cache Objects (Token A and Token B).
for (i = 0; i < 2 ; i++) {
Token tokenAdded = new Token(UUID.randomUUID().toString(),TOKEN_AVAILABLE, networkID);
tokenCache.put(tokenAdded.getTokenID(), tokenAdded);
tokenCache.addMapListener((MapListener) new TokenCacheListener(), tokenAdded.getTokenID(), false);
Now assume that updates are made to Token A and Token B simuntaneosly.
Why do i observe in my diagnostic messages that only one Listener is invoked at a given point of time.
Which means I see Listener A getting invoked and then once invocation of Listener A is complete I see Listener B bieng invoked.
Ideally I would want both listeners to be invoked simultaneously rather than in a one off fashion.
Here is the code for my token cache Listener
package oracle.communications.activation.asap.ace;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import com.tangosol.net.CacheFactory;
import com.tangosol.net.NamedCache;
import com.tangosol.util.AbstractMapListener;
import com.tangosol.util.Filter;
import com.tangosol.util.MapEvent;
import com.tangosol.util.MapListener;
import com.tangosol.util.ObservableMap;
import com.tangosol.util.ValueUpdater;
import com.tangosol.util.extractor.PofExtractor;
import com.tangosol.util.extractor.PofUpdater;
import com.tangosol.util.filter.AndFilter;
import com.tangosol.util.filter.EqualsFilter;
import com.tangosol.util.filter.LikeFilter;
import com.tangosol.util.filter.LimitFilter;
import com.tangosol.util.processor.UpdaterProcessor;
public class TokenCacheListener extends AbstractMapListener {
NamedCache asdlCache;
NamedCache tokenCache;
AceCacheFactory cacheFactoryBean = new AceCacheFactory();
private final int PAGE_SIZE = 1;
private static Logger logger = Logger.getLogger(ConnectionManager.class
.getName());;
* An instance of the JCAModeler EJB, represents the JCA-JNEP
JCAModeler jcaBean;
* This is a utility method and prints the tokens cache.
public String printTokenCache() {
NamedCache tokenCache = cacheFactoryBean.getCache("tokenCache");
LikeFilter tokenList = new LikeFilter(new PofExtractor(String.class,
Token.STATE), "%", (char) 0, false);
Set keySet = tokenCache.keySet(tokenList);
StringBuffer cachedTokenList = new StringBuffer("\n################################## Token(s) Cache ##################################");
int counter = 1;
for (Object tokenInCache: keySet) {
Token tokenObject = (Token) tokenCache.get(tokenInCache.toString());
cachedTokenList.append("\nS.NO:" + (counter++)
+ "\t ID:" + tokenInCache.toString()
+ "\t State:" + Token.tokenToString(tokenObject.getState()));
cachedTokenList.append("\n####################################################################################");
return cachedTokenList.toString();
* This method is a utility method and it prints all the ASDL(s) currently present on the
* asdlCache.
private String printASDLCache() {
NamedCache asdlCache = cacheFactoryBean.getCache("asdlCache");
LikeFilter asdlList = new LikeFilter(new PofExtractor(String.class,
Asdl.NETWORKID), "%", (char) 0, false);
Set keySet = asdlCache.keySet(asdlList);
StringBuffer cachedASDLList = new StringBuffer("\n################ ASDL Cache ######## ########");
int counter = 1;
for (Object asdlInCache: keySet) {
cachedASDLList.append("\nS.NO:" + (counter++) + "\t ID:" + asdlInCache.toString());
cachedASDLList.append("\n################ ASDL Cache ######## ########\n");
return cachedASDLList.toString();
public TokenCacheListener() {
public void checkASDLCache(MapEvent Event) {
// Not currently used
public void entryUpdated(MapEvent Event) {
Token newToken = (Token) Event.getNewValue();
Token oldToken = (Token) Event.getOldValue();
logger.info("\n=============================================================================================="
+ "\nTOKEN CACHE LISTENER"
+ "\n=============================================================================================="
+ printTokenCache()
+ "\n==============================================================================================");
if ((oldToken.getState() == Token.TOKEN_RESERVED)
&& (newToken.getState()== Token.TOKEN_AVAILABLE)) {
String networkID = newToken.getNeID();
asdlCache = cacheFactoryBean.getCache("asdlCache");
tokenCache = cacheFactoryBean.getCache("tokenCache");
EqualsFilter filterNE = new EqualsFilter(new PofExtractor(String.class,Asdl.NETWORKID), networkID);
LimitFilter limitFilter = new LimitFilter(filterNE, PAGE_SIZE);
Set removeASDL = asdlCache.keySet(limitFilter);
Iterator asdlIterator = removeASDL.iterator();
if (asdlIterator.hasNext()) {
logger.info(printASDLCache());
ValueUpdater updater = new PofUpdater(Token.STATE);
System.out.println("Token ID:" + newToken.getTokenID());
UpdaterProcessor updaterProcessor = new UpdaterProcessor(updater, Integer.toString(Token.TOKEN_RESERVED));
tokenCache.invoke(newToken.getTokenID(), updaterProcessor);
jcaBean = new JCAModeler(tokenCache);
Object asdlID = asdlIterator.next();
Asdl provisionAsdl = (Asdl) asdlCache.get(asdlID);
asdlCache.remove(asdlID);
jcaBean.provision(provisionAsdl, newToken.getTokenID());
logger.info(printTokenCache());
logger.info(printASDLCache());
I only see one instance of this listener alive at any given point of time.
Edited by: 807103 on Nov 3, 2011 1:00 PM
Edited by: 807103 on Nov 3, 2011 1:12 PM -
What's wrong with my multi-threaded Matrix Mult. code? 1 thread is fastest
For some reason, 1 thread performs the best. What's wrong with my implementation?
import java.util.Random;
import java.util.Date;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
public class Matrix {
private int values[][];
private int rows;
private int columns;
public Matrix(int r, int c) {
this.rows = r;
this.columns = c;
this.values = new int[r][c];
private void randomize() {
Random generator = new Random();
for (int r = 0; r < this.rows; r++) {
for (int c = 0; c < this.columns; c++) {
this.values[r][c] = generator.nextInt(10);
public String toString() {
String out = "";
for (int r = 0; r < this.rows; r++) {
for (int c = 0; c < this.columns; c++) {
if (c == 0) out += "[";
else out += "\t";
out += this.values[r][c];
out += "]\n";
return out;
public boolean equals(Object obj) {
Matrix other = (Matrix) obj;
if (this.columns != other.columns || this.rows != other.rows) {
return false;
for (int r = 0; r < this.rows; r++) {
for (int c = 0; c < this.columns; c++) {
if (this.values[r][c] != other.values[r][c]) {
return false;
return true;
// matrix multiplication using single thread
public Matrix times(Matrix other) {
assert(this.columns == other.rows);
Matrix out = new Matrix(this.rows, other.columns);
for (int r = 0; r < this.rows; r++) {
for (int c = 0; c < other.columns; c++) {
int dotProduct = 0;
for (int z = 0; z < this.columns; z++) {
dotProduct += this.values[r][z] * other.values[z][c];
out.values[r][c] = dotProduct;
return out;
// matrix multiplication with many threads
public Matrix ptimes(Matrix other, int numberOfThreads) throws InterruptedException { // parallel
assert(this.columns == other.rows);
Matrix out = new Matrix(this.rows, other.columns);
ExecutorService threadExecutor = Executors.newFixedThreadPool(numberOfThreads);
for (int r = 0; r < this.rows; r++) {
for (int c = 0; c < other.columns; c++) {
threadExecutor.execute(new HelperThread(r, c, this, other, out));
threadExecutor.shutdown();
threadExecutor.awaitTermination(2, TimeUnit.DAYS);
return out;
private class HelperThread implements Runnable {
private int row;
private int col;
private Matrix a;
private Matrix b;
private Matrix out;
HelperThread(int r, int c, Matrix a, Matrix b, Matrix o) {
this.row = r;
this.col = c;
this.a = a;
this.b = b;
this.out = o;
public void run() {
int dotProduct = 0;
for (int z = 0; z < a.columns; z++) {
dotProduct += this.a.values[row][z] * this.b.values[z][col];
this.out.values[row][col] = dotProduct;
public static void main(String[] args) throws InterruptedException {
int size = 100;
Matrix a = new Matrix(size, size);
a.randomize();
Matrix b = new Matrix(size, size);
b.randomize();
for (int t = 1; t < 15; t++) {
long start = new Date().getTime();
System.out.print(t + " threads: ");
Matrix c = a.ptimes(b, t);
//System.out.println(c);
long finish = new Date().getTime();
System.out.println((finish - start) + " milliseconds");
Matrix d = a.times(b);
assert(c.equals(d));
}This one is even faster. On my dual core I get:
Warmup
Single Threaded
5.20616 milliseconds
5.52872 milliseconds
5.12708 milliseconds
5.59048 milliseconds
5.16104 milliseconds
5.1838 milliseconds
5.37104 milliseconds
5.1788 milliseconds
5.18636 milliseconds
5.15736 milliseconds
Multi Threaded with 2 threads
3.22184 milliseconds
2.86552 milliseconds
2.86284 milliseconds
3.67032 milliseconds
3.08032 milliseconds
2.97388 milliseconds
2.93084 milliseconds
3.44012 milliseconds
2.89744 milliseconds
2.88136 milliseconds
As you can see the Multi-Threaded versions are now faster.
// matrix multiplication with many threads
ExecutorService threadExecutor = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());
public Matrix ptimes(Matrix other) throws InterruptedException, ExecutionException {
assert (this.columns == other.rows);
Matrix out = new Matrix(this.rows, other.columns);
Future futures[] = new Future[rows];
for (int r = 0; r < this.rows; r++) {
futures[r] = threadExecutor.submit(new HelperThread(r, this, other, out));
for(Future f : futures) {
f.get();
return out;
private class HelperThread implements Callable<Object> {
private int row;
private Matrix a;
private Matrix b;
private Matrix out;
HelperThread(int r, Matrix a, Matrix b, Matrix o) {
this.row = r;
this.a = a;
this.b = b;
this.out = o;
public String call() throws Exception {
int dotProduct = 0;
for (int c = 0; c < b.columns; c++) {
for (int z = 0; z < a.columns; z++) {
dotProduct += this.a.values[row][z] * this.b.values[z][c];
this.out.values[row][c] = dotProduct;
return null;
public static void main(String[] args) throws InterruptedException, ExecutionException {
int size = 100;
Matrix a = new Matrix(size, size);
a.randomize();
Matrix b = new Matrix(size, size);
b.randomize();
System.out.println("Warmup");
for (int t = 0; t < 1000; t++) {
Matrix c = a.ptimes(b);
Matrix d = a.times(b);
assert (c.equals(d));
System.out.println("Single Threaded");
for (int t = 0; t < 10; t++) {
long start = System.nanoTime();
Matrix d = a.times(b);
long finish = System.nanoTime();
System.out.println((finish - start)/1000000.0 + " milliseconds");
System.out.println("Multi Threaded with " + Runtime.getRuntime().availableProcessors() + " threads");
for (int t = 0; t < 10; t++) {
long start = System.nanoTime();
Matrix c = a.ptimes(b);
long finish = System.nanoTime();
System.out.println((finish - start)/1000000.0 + " milliseconds");
Matrix d = a.times(b);
assert (c.equals(d));
System.exit(0);
} -
Multi threading under single file channel
Hi,
We have File-Proxy scenario .
We are using fCC sender channel and using
recordset sequence as varaibale
recordsets per message was 250.
When large size file like 2GB was processed, PI is taking 45-50 min to process the file and from proxy end its taking 8 hrs to process this file.
we are using one channel and 250 recordsets per message by chunking file and process to target. We are following EOIO for sequence for these chunk files.
with this approach in PI target system proxy is taking huge time to process.
experts suggested using multi threading and multiple channels are the ideal solution for this issue.
am expecting with multiple channels and multi threading will cause issue for receiver proxy because of more objects and current approach is fine.
Please suggest any other alternatives we can acheive in PI with respect to this issue?
Note: I checked blog for file chunk option under Adv parameters and I cant use that here as FCC and Mapping is there .
Rgds,
amanHi Aman,
We had file to proxy interface and the XML payload of the proxy was around 400mb...to reduce the time taken in PI in mapping step we reduced the XML payload of the proxy by cutting the XML tagnames.
for example an xml field <firstname>Anand</firstname> was converted to <f>Anand</f>
with this we were able to achieve about 40-50% reduction in XML payload the file and a good improvement in the time taken by PI mapping to process the file.
Hope it helps,
Thanks,
Anand -
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