Clarification of the handle/body idiom in multi threaded applications

Hello
As some DBXML classes use the handle-body idiom (handle/body idiom in some docs), could someone please clarify the consequences of that in a multi threaded application like a web container?
For 100% Java people, like me, this is known in the Java world as 'programming towards interfaces', or as the Bridge pattern; which is seen as good practice.
Let's take an example. The class XmlQueryContext is not thread safe, but it has a copy constructor. Imagine that your web application has one XmlQueryContext, that we never use in a query, but that we prepare only to be copied in new threads. Is it thus safe to instantiate various new XmlQueryContexts using that copy constructor in various new threads and use them simultaneously?
Thank you
Koen
PS What I am really asking here is if somebody could please translate the following to Java parlé:
A copy constructor is provided for this class. The class is implemented using a handle-body idiom. When a handle is copied both handles maintain a reference to the same body.

As a Java user you do not have to worry about how the C++ copy constructors behave. In the Java API if a copy constructor exists for the object, then the copy constructor will copy all of the original object's data into a new object (XmlContainer is the one exception to this rule, generally one should not use that copy constructor at all). So in short, what you plan to do will work.
Lauren Foutz

Similar Messages

Multi-Thread application and common data

I try to make a multi-Thread application. All the Threads will update some common data.
How could I access the variable �VALUE� with the Thread in the following code:
public class Demo {
private static long VALUE;
public Demo(long SvId) {
VALUE = 0;
public static class makeThread extends Thread {
public void run() {
VALUE++;
public static long getVALUE() {
return VALUE;
The goal is to get the �VALUE� updated by the Thread with �getVALUE()�
Thanks for your reply
Benoit

That code is so wrong in so many ways......
I know you're just experimenting here, learning what can and can't be done with Threads, but bad habits start early, and get harder to kick as time goes on. I am going to give a little explanation here about what's wrong, and what's right.. If you're going to do anything serious though, please, read some books, and don't pick up bad habits.
Alright, The "answer" code. You don't use Thread.sleep() to wait for Threads to finish. That's just silly, use the join() method. It blocks until the threads execution is done. So if you have a whole bunch of threads in an array, and you want to start them up, and then do something once they finish. Do this.
for(int k=0; k<threads.length; k++) {
threads[k].start();
for(int k=0; k<threads.length; k++) {
threads[k].join();
System.out.println("All Threads Done");Now that's the simple problem. No tears there.
On to the java memory model. Here where the eye water starts flowing. The program you have written is not guarenteed to do what you expect it to do, that is, increment VALUE some amount of time and then print it out. The program is not "Thread Safe".
Problem 1) - Atomic Operations and Synchronization
Incrementing a 'long' is not an atomic operation via the JVM spec, icrementing an int is, so if you change the type of VALUE to an int you don't have to worry about corruption here. If a long is required, or any method with more then one operation that must complete without another thread entering. Then you must learn how to use the synchronized keyword.
Problem 2) - Visiblity
To get at this problem you have to understand low level computing terms. The variable VALUE will NOT be written out to main memory every time you increment it. It will be stored in the CPUs cache. If you have more then one CPU, and different CPUs get those threads you are starting up, one CPU won't know what the other is doing. You get memory overwrites, and nothing you expect. If you solve problem 1 by using a synchronized block, you also solve problem 2, because updating a variable under a lock will cause full visiblity of the change. However, there is another keyword in java.. "volatile".. A field modified with this keyword will always have it's changes visible.
This is a very short explaination, barely scratching the surface. I won't even go into performance issues here. If you want to know more. Here's the resources.
Doug Lea's book
http://java.sun.com/docs/books/cp/
Doug Lea's Site
http://g.cs.oswego.edu
-Spinoza

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

Java Security Manager in Multi-threaded application

I am writing a multi-threaded application listening (TCP and UDP) to several ports. To help implement certain security features (eg. refusing connections from certain ip address), I'm using the java.lang.SecurityManager (by subclassing it). I am having a few problems and queries and am hoping someone here can help me.
1. As all the threads are calling the checkAccept(host, port) method. Is there a way to know which thread is currently accessing the security manager? For example if host A were to make 2 connections to the application, one to thread 1 (say listening to port 5001) and the other to to thread 2 (say listening to port 5002). I intend to refuse the connection to thread 2 but there is not way of differentiating the 2 connections since they are from the same host and there isnt any way of knowing their port number.
2. Are calls to the Security Manager thread safe?
I have been having this problem for a long time, would appreciate if someone can help point me to the right direction. cheers.

1. As all the threads are calling the
checkAccept(host, port) method. Is there a way to
know which thread is currently accessing the security
manager?Just use Thread.currentThread(). As specified in the Javadoc for e.g. SecurityManager.checkAccept().
2. Are calls to the Security Manager thread safe? No.

Multi-threaded application crashing the VM

Hi,
I have a multi-threaded (about 120 threads) application which crashes without after running for a while.
I get this in the windows event viewer
Faulting application java.exe, version 0.0.0.0, faulting module kernel32.dll, version 5.2.3790.0, fault address 0x000017b1.
Anyone knows why this would happen?
- vineet

Hi Alexis,
Thanks for the response to my post!!
Which version of the JVM?C:\>java -version
java version "1.4.2_05"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_05-b04)
Java HotSpot(TM) Client VM (build 1.4.2_05-b04, mixed mode)
Are you using the -server option?I was not using this option earlier but even on using this the jvm crashes after running for sometime.
I am using these jvm options now -
java -server -Xss128K -Xms256M -Xmx512M
- vineet

The problem of profiling a multi-thread flash game using adobe scout cc

I have a multi-thread flash game code, it can run perfectly. The main swf creates another swf which will connect to a remote server. I can get profiling information of the main swf using adobe scout cc, but the problem is that I can't get profiling information of another swf ! The scout complains " can't start a session because the telemetry data isn't valid" for another swf. Although some times, the scout does not complain, the Summary Panel of scout provides information“We encountered an error while processing this session: Some of the data we present may not be correct". And the scout log file shows:
Log file created: 2014/11/20 15:35:08
11/20/2014 15:35:08.395 Scout starting up.
11/20/2014 15:35:08.471 InitDNSService failed
11/20/2014 15:36:47.055 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [100000,200000] is greated than its parent
11/20/2014 15:36:47.057 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [200000,300000] is greated than its parent
11/20/2014 15:36:47.058 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [300000,400000] is greated than its parent
11/20/2014 15:36:47.058 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [400000,500000] is greated than its parent
11/20/2014 15:36:47.061 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [500000,600000] is greated than its parent
11/20/2014 15:36:47.062 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [600000,700000] is greated than its parent
11/20/2014 15:36:47.063 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [700000,800000] is greated than its parent
11/20/2014 15:36:47.063 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [800000,900000] is greated than its parent
11/20/2014 15:36:47.064 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [900000,1000000] is greated than its parent
11/20/2014 15:36:47.064 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [1000000,1100000] is greated than its parent
11/20/2014 15:36:47.064 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [1100000,1200000] is greated than its parent
11/20/2014 15:36:47.065 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [1200000,1300000] is greated than its parent
11/20/2014 15:36:47.065 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [1300000,1400000] is greated than its parent
11/20/2014 15:36:47.065 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [1400000,1500000] is greated than its parent
11/20/2014 15:36:47.066 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [1500000,1600000] is greated than its parent
11/20/2014 15:36:47.066 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [1600000,1700000] is greated than its parent
11/20/2014 15:36:47.066 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [1700000,1800000] is greated than its parent
11/20/2014 15:36:47.067 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [1800000,1900000] is greated than its parent
11/20/2014 15:36:47.067 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [1900000,2000000] is greated than its parent
11/20/2014 15:36:47.067 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [2000000,2100000] is greated than its parent
11/20/2014 15:36:47.068 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [2100000,2200000] is greated than its parent
11/20/2014 15:36:47.068 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [2200000,2300000] is greated than its parent
11/20/2014 15:36:47.068 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [2300000,2400000] is greated than its parent
11/20/2014 15:36:47.069 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [2400000,2500000] is greated than its parent
11/20/2014 15:36:47.069 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [2500000,2600000] is greated than its parent
11/20/2014 15:36:47.069 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [2600000,2700000] is greated than its parent
11/20/2014 15:36:47.070 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [2700000,2800000] is greated than its parent
11/20/2014 15:36:47.070 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [2800000,2900000] is greated than its parent
11/20/2014 15:36:47.070 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [2900000,3000000] is greated than its parent
11/20/2014 15:36:47.071 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [3000000,3100000] is greated than its parent
11/20/2014 15:36:47.071 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [3100000,3200000] is greated than its parent
11/20/2014 15:46:30.931 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [100000,200000] is greated than its parent
11/20/2014 15:46:30.933 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [200000,300000] is greated than its parent
11/20/2014 15:46:30.936 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [300000,400000] is greated than its parent
11/20/2014 15:46:30.937 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [400000,500000] is greated than its parent
11/20/2014 15:46:30.937 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [500000,600000] is greated than its parent
11/20/2014 15:46:30.937 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [600000,700000] is greated than its parent
11/20/2014 15:46:30.937 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [700000,800000] is greated than its parent
11/20/2014 15:46:30.938 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [800000,900000] is greated than its parent
11/20/2014 15:46:30.938 <2896> <telemetryCore.Query> <1> Incorrect data: Memory category 7 for frame stats query over time interval [900000,1000000] is greated than its parent
I run flash code directly on flash_player_11_7_sa.exe. I think the problem may have something to do with ActionScript Sampler of scout, because I can get the correct profiling information without ActionScript Sampler.
But I don't know what the information in the log file means.

We are using Microsoft SQL Server 2008 . but it's well with MySQL & JBoss

The CPU utilization is 0% for the other remaining processes when multi threading is used

I am new to AE ,so I am trying to render a project enabling multi threading process the additional processes are present but their utilization is 0% .
I want to juice out every single CPU utiliaztion .
ANy help is greatly appriciated,.
My system specs:
AMD 9690 4.7 Ghz 8 core
32 GB DDR3
C:\256 GB Solid Satte Raid 0
GeForce 780 Ti DDR5 3GB

It is very tempting to try and use all of your system resources and multiprocessing for all your projects, but this is not the way After Effects works. Many third-party plug-ins, many codecs, and many operations do not respond well to multiprocessing. All it takes is one process in your entire thread that is not MP aware to foul the whole thing and give you longer render times.
You are also leaving zero processors for the rest of your computer. Not a wise idea.
After effects renders one frame at a time. One HD frame even with multiple layers of pixel processing just isn't that much data. It does take a while to do the calculations, but expecting to have every one of your CPUs jacked up at 100% to render a single frame of video is expecting an awful lot.
I would suggest that you read up on optimizing After Effects for your computer. Do not expect to be able to utilize 100% of your system resources at all times. That's just not the way processing video on a pixel by pixel basis works.
Just a little FYI, for 99% of my projects in After Effects I have render multiple frames simultaneously turned off. It just doesn't work with most of the things I do. Sorry for the disappointment.

Question using Java API in a multi threaded application for MDX queries

Currently I’m building a web application that makes a lot of MDX calls using the Essbase Java API. Each time we run an MDX call we basically run the following code:
IEssbase ess = IEssbase.Home.create(IEssbase.JAPI_VERSION);
IEssDomain dom = ess.signOn(userName, password, false, null, "embedded");
IEssCubeView cv = cv=dom.openCubeView("view", hostName, appName, cubeName);
IEssOpMdxQuery op = cv.createIEssOpMdxQuery();
op.setQuery(false,mdx,false,IEssOpMdxQuery.EEssMemberIdentifierType.NAME);
cv.performOperation(op);
IEssMdDataSet mddata = cv.getMdDataSet();
cv.close();
My questions is, is this the correct way to use the API in multi threaded environment where many users may be hitting the application at the same time? For every request do I need to create a separate IEssbase object and sign on to an IEssDomain? Or can I use a single IEssbase and IEssDomain object for the entire application? If not should I call the IEssDomain.signOff() method after each user’s request has completed? Which of the above objects are thread safe? I’m using Essabae 9.3.1. Any insight would be really appreciated.
Thanks
David

Thanks for the input friend,
I should have mentioned that in my application all
connections to Essbase use the same user name and
password so the filtering isn’t a concern. This is my
first Java application using Essbase has a data
source, I’m used to connecting to various SQL
databases and I always use a connection pool, how is
connection pooling handled in the Essbase java API?I'm not sure what happened to it since I never used it, but there used to be something called the High Availability Services or something that was essentially a connection pool for Essbase JAPI connections, but it required an extra license.
Since you don't care about identity (everyone has full access to everything), you can create your own connection pool, but you'll have to manage your multithreading yourself. Its been this way since the beginning. The C API isn't/wasn't thread-safe either (we tried).

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 PM

I 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.

Error when using same QueueSession in a multi threaded application

I have deployed a OSSJ Trouble Ticket refererence Implementation on Sun Java System App Server Platform Edition 8.1 default server.
The TT server listens on queue MessageQueue and sends its reply on MessageReplyQueue
The application that sends the request to the TT server should support concurrent requests using threads.
The sender application creates a QueueConnection and a QueueSession.
This QueueSession is shared by all the threads that send the request to the TT server.
Each thread creates its own QueueSender, TemporaryQueue which is set as replyTo in the message, QueueReceiver using the TemporaryQueue in the run method
When the application is run multiple times i get the following exception
javax.jms.IllegalStateException: [C4055]: Resource in conflict. Concurrent operations on a session.
at com.sun.messaging.jmq.jmsclient.SessionImpl.setInSyncState(SessionImpl.java:2177)
at com.sun.messaging.jmq.jmsclient.SessionImpl.acknowledge(SessionImpl.java:972)
at com.sun.messaging.jmq.jmsclient.MessageConsumerImpl.receive(MessageConsumerImpl.java:375)
at com.sun.messaging.jmq.jmsclient.MessageConsumerImpl.receive(MessageConsumerImpl.java:347)
at xvt.tt.MessageSenderMultiThread.run(MessageSenderMultiThread.java:112)
The code looks as follows
public class MessageSenderMultiThread extends Thread {
private String strMessage = null;
private QueueSender queueSender = null;
private QueueReceiver queueReceiver = null;
private TextMessage message = null;
private TemporaryQueue tempQueue = null;
private QueueConnection tempQC = null;
private QueueSession tempQS = null;
private Queue tempQ = null;
String inputQname = "MyQueue";
String outputQname = "A";
private int sleepTime;
static InitialContext jndiContext = null;
Queue replyQueue=null;
Hashtable sessions=null;
static QueueConnection queueConnection = null;
public static String readFromFile(String fileName) {
String line = null;
try {
FileReader fr = new FileReader(fileName);
BufferedReader br = new BufferedReader(fr);
String temp = "";
line = "";
while ((temp = br.readLine()) != null) {
//System.out.println("line is"+line);
if (temp != null)
line = line + temp;
return line;
} catch (Exception ex) {
System.out.println("Exception occurred,Ex" + ex);
return line;
MessageSenderMultiThread(String strMsg, int sTime, QueueConnection qC, QueueSession qS, Queue q, String name) {
super(name);
this.strMessage = strMsg;
this.sleepTime = sTime;
this.tempQC = qC;
this.tempQS = qS;
this.tempQ = q;
sessions=new Hashtable();
System.out.println("Inside Constructior");
public void run() {
try {
queueSender = tempQS.createSender(tempQ);
tempQueue = tempQS.createTemporaryQueue();
queueReceiver = tempQS.createReceiver(tempQueue);
//queueReceiver = tempQS.createReceiver(replyQueue);
message = tempQS.createTextMessage();
message.setText(this.strMessage);
message.setJMSReplyTo(tempQueue);
//message.setJMSReplyTo(replyQueue);
message.setJMSCorrelationID("1234");
queueSender.send(message);
System.out.println(message.getText());
tempQC.start();
//while (true) {
Message m = queueReceiver.receive();
if (m != null) {
if (m instanceof TextMessage) {
message = (TextMessage) m;
if (message != null) {
System.out.println("########################corr id::"+message.getJMSCorrelationID());
queueReceiver.close();
//System.out.println("message:: " + message.getText() + "Thread Name " + this.getName());
} else
System.out.println("NULL");
} //else
//break;
System.out.println("Exiting !");
} catch (JMSException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
public static void main(String args[]) {
String inputQname = "System/RI/ApplicationType/TroubleTicket/Application/1-0;0-0;OSSJTTRI/Comp/MessageQueue";
QueueConnectionFactory queueConnectionFactory = null;
QueueSession queueSession = null;
Queue inputQueue = null;
try {
jndiContext = new InitialContext();
queueConnectionFactory = (QueueConnectionFactory) jndiContext.lookup("System/RI/ApplicationType/TroubleTicket/Application/1-0;0-0;OSSJTTRI/Comp/QueueConnectionFactory");
inputQueue = (Queue) jndiContext.lookup(inputQname);
queueConnection = queueConnectionFactory.createQueueConnection();
queueSession = queueConnection.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);
} catch (JMSException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
String strRequest = null;
strRequest = readFromFile("C:/ISM/getTroubleTicketsByKeysRequest.xml");
new MessageSenderMultiThread(strRequest, 100, queueConnection, queueSession, inputQueue, "Thread1").start();
strRequest = readFromFile("C:/ISM/getTroubleTicketsByKeysRequest1.xml");
new MessageSenderMultiThread(strRequest, 100, queueConnection, queueSession, inputQueue,"Thread2").start();
System.out.println("OVER");
// System.exit(-1);
}

A session is single threaded (so it can not be used by different threads and generate valid behavior). This behavior is covered in @ setion 4.4 of the JMS specification
If you need multiple threads to process messages you should either:
* have them share a single session
* read messages in from the session in a single thread and pass them off to
other threads processing the message
On the second option, you must have the "reading" thread also acknowledge the message in client acknowledge (or commit in transactions)

System() from a multi-threaded app

The man page for system(3S) states that its MT-Level is "unsafe." Nonetheless we need to call system() from a multi-threaded application. At present we "just go ahead and do it," and of course it doesn't work well. I'm not entirely sure of the details of the failure -- it's more a colleague's baby than mine -- but I believe the system() call often fails to complete ("hangs").
Is there a thread-safe equivalent-or-replacement for system()? Surely the need to launch other applications from a multi-threaded application is commonplace today? How is it done safely-and-correctly?

Hi,
system() is not thread safe because it internally uses vfork() system call which in turn is not MT-safe . When you do a vfork()/fork1() in threaded applications only the thread which issues the call gets duplicated in the child process , which could result in dead lock problems . Solution of running system() under the protection of a lock may not help to avoid this problem.
If you're using Solaris thread library , fork() + exec() is a safe substitute for system() . If you are using Posix library , use pthread_atfork() to make sure that you handle the locks properly before/after forking.
Hope this helps.
Thanks,
Prajeesh

What is the max. count of internal worker-threads in B1iSN 88?

Hi Experts,
We have an installation of B1iSN 88 with an ECC 6.0 and 54 SAP Business One installation. The Hardware is 8 Core multi-threads processor. 32GB Memory. Now we have a problem with the queuing of Events. What we have found is that the configuration of the internal worker-threads is set to -1(please see below for the settings). We change the settings to xcl.threads=20 and it improves the queuing. My question is what is the max. count of internal worker-threads per core? so that we can know how many worker will set and if we need to upgrade the CPU to 16 Core..
# The max. count of internal worker-threads afforded for the internal Scheduler (defaults to 1)
# The value of 0 means that there is no limit (what in general should not be set up).
# A negative value means the count of threads per available processor
xcl.threads=-1
Regards,
Wilson

You're very welcome.
Yes, they are very nice machines.
What a jump in performance when I swapped out the Pentium 4 620 mine had, for the PD 945, and tossed in 4 GB of memory.
That box will also run the Radeon HD 6570 with no problem too, which is what I put in mine.
The downside of that model is that there are no settings for ahci or raid.
I own or have owned every CMT since the d510 with the exception of the dc7900.
My main PC is now the 8200 Elite CMT which I installed W8.1 on.
It has an i7-2600 processor and 32 GB of memory, 1 TB SATA III hard drive.
I threw in a Radeon HD 6670 in that one.
Best Regards,
Paul

Multi-threading

Hi folks,
I need to have one Connection object and multiple Statement objects created from this Connection Object. Is it safe to do this from a multi-threaded application?
Does createStatement() destroy any previously created Statement?

You can have multiple statements in different threads coming of the same connection.
But, all such statements will be part of the same transacion. A DML in one thread will be reflected in a query in another thread.
If this not what you wanted, then you can have a connection pool and get connections from it in the individual threads.

XA & Oracle - Multi-threaded

Hi All,
The Oracle XA documentation says that multi threaded
applications are
possible. But when i tried to open a connection to the DB using
XA_OPEN in
thread session with the same string it is giving an error in the
second
thread saying "XA_ERRPROTO: DB Name not unique", however sucess
in the first
thread. So multi-thread means multiple connections to diff DB.
So i opened one connection in the main thread, and i did a
XA_START with
diff. XID in both the threads. Again here in the second thered
the error is
"XA_ERRPROTO: Thread already associated".
So if these are standard ones how to write a mult threaded
application using
XA which uses only one DB.
-prabha
null

要好好看，楼主为啥不解释一下呢，或者简单翻译一下思想呢。　
为了到单位不忘记该连接，故发此贴，希望不要认为是灌水。

Multi-thread BackgroundWorker

Hi,
Is BackgroundWorker a recommended way to write a multi-threading application? If not, what is the preferred way for multi-threading programming?
Thanks in advance!

Thanks for the comments.
Below is the scenario:
A main application is monitoring any incoming files in a network folder.
Whenever a new file turns up, application will start a BackgroundWorker to process the file.
There may be many files constantly go to this folder
Q: do I need to create a BackgroundWorker for each individual file?
Thanks for your help.

Clarification of the handle/body idiom in multi threaded applications

Similar Messages

Maybe you are looking for