Spawning threads from a webapp

Can I spawn a thread from a webapp the same way I do in a normal java app?
Is there anything I should know before I get started doing this(i.e. special circumstances)?
Any comment are welcome, thanks in advance
silastad

anyone???, I know that you can spawn a thread from a webapp, I just want to know if there is anything in particular that I should look out for before I begin.
silastad

Similar Messages

  • Spawning threads from within a UnicastRemoteObject

    I have a question regarding spawning threads from within a class that extends UnicastRemoteObject. Would it be okay to spawn new thread(s) in the constructor/ remote methods of the class that extends UnicastRemoteObject .? Are there any pitfalls to doing so? Is it against the suggested practice of writing RMI server code?
    rajkumar

    You can do anything you like in the Class that extends URO.
    The classic problem of doing anything within a constructor is that the object under construction may not be available to the threads you are spawning. That is, since the object is not fully constructed, any fields the new threads need may not be available. There have been discussions on this subject in the forums before. You might give a look and see.

  • EJB client spawning threads

    We've got problems with respect to the number of EJB client threads (ExecuteThread) spawned by WebLogic in a client JVM. As the number of threads increase (~1700 in a JVM with 512Mb of memory and 2 hours of uptime), the JVM performance degrades substantially - although almost all these threads are waiting for requests, as one can see in the thread dump attached bellow.
    This problem happens in an integration scenario involving both WebLogic (8.1 and 6.1 as service providers) and webMethods Integration Server (version 6.0.1); the webMethods EJB adapter (version 1.2) acts like EJB client from the WebLogic instances, and the "EJB client spawning threads" can be detected by thread dumps extracted from the Integration Server JVM. The URL property from the wm EJB adapter has been setup as t3://server:port. The Integration Server runs with Java HotSpot(TM) Server VM (build 1.4.2 1.4.2.02-040225-19:18-PA_RISC2.0 PA2.0 (aCC_AP), mixed mode) JRE in HP-UX (11.11) environment.
    Although we couldn't reproduce this problem in a prod like environemnt, we'd identified that initially, WebLogic (weblogic.jar from WebLogic 6.1) spawns 5 ExecuteThreads plus 3 additional threads (TimeEventGenerator, SpinnerRandomSource and HighPriority TimeEventGenerator) in the first access of an EJB not matter the instance used, as well as two new threads (ExecuteThread) for each access to new WebLogic instances (different from previously accessed WebLogic instances). With weblogic.jar from the WebLogic 8.1 SP4 the behavior is slightly different: from the second instance access toward, only two new Threads (ExecuteThread in weblogic.JavaSocketReaders queue) are created.
    We have also noticed that this problem should not be reflect of context classloaders because the counter of the ExecuteThread for the default pool only increases; in case of a pool cached in separate context classloaders, we should see "duplicate" threads with the same counter (starting with 0), which is not the case.
    The questions are 1) why weblogic is spawning so much threads; 2) is there any setup/config to limit the number of WebLogic threads in the client context ?
    Excerpt from the thread dump:
    Full thread dump Java HotSpot(TM) Server VM (1.4.2 1.4.2.02-040225-19:18-PA_RISC2.0 PA2.0 (aCC_AP) mixed mode):
    "ExecuteThread: '1749' for queue: 'default'" daemon prio=10 tid=05734140 nid=4813 lwp_id=583942 in Object.wait() [0x0dfbe000..0x0dfbe4f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <4a5ef9f0> (a weblogic.common.internal.DynaQueue)
         at weblogic.common.internal.DynaQueue.getW(DynaQueue.java:228)
         - locked <4a5ef9f0> (a weblogic.common.internal.DynaQueue)
         at weblogic.socket.JavaSocketMuxer.processSockets2(JavaSocketMuxer.java:252)
         at weblogic.socket.JavaSocketMuxer.processSockets(JavaSocketMuxer.java:233)
         at weblogic.socket.SocketReaderRequest.execute(SocketReaderRequest.java:24)
         at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:139)
         at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
    "ExecuteThread: '1742' for queue: 'default'" daemon prio=10 tid=04c263f0 nid=4812 lwp_id=583845 runnable [0x06449000..0x064494f0]
         at java.net.SocketInputStream.socketRead0(Native Method)
         at java.net.SocketInputStream.read(SocketInputStream.java:129)
         at weblogic.socket.JavaSocketMuxer.processSockets2(JavaSocketMuxer.java:281)
         - locked <4a5ee690> (a java.net.Socket)
         at weblogic.socket.JavaSocketMuxer.processSockets(JavaSocketMuxer.java:233)
         at weblogic.socket.SocketReaderRequest.execute(SocketReaderRequest.java:24)
         at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:139)
         at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
    "ExecuteThread: '1735' for queue: 'default'" daemon prio=10 tid=05733fd8 nid=4811 lwp_id=583784 in Object.wait() [0x064ca000..0x064ca4f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <4c40a6b8> (a weblogic.kernel.ExecuteThread)
         at java.lang.Object.wait(Object.java:429)
         at weblogic.kernel.ExecuteThread.waitForRequest(ExecuteThread.java:94)
         - locked <4c40a6b8> (a weblogic.kernel.ExecuteThread)
         at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:118)
    "ExecuteThread: '1734' for queue: 'default'" daemon prio=10 tid=01ecd940 nid=4810 lwp_id=583783 in Object.wait() [0x0654b000..0x0654b4f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <4c40a728> (a weblogic.kernel.ExecuteThread)
         at java.lang.Object.wait(Object.java:429)
         at weblogic.kernel.ExecuteThread.waitForRequest(ExecuteThread.java:94)
         - locked <4c40a728> (a weblogic.kernel.ExecuteThread)
         at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:118)
    "ExecuteThread: '1733' for queue: 'default'" daemon prio=10 tid=05733e70 nid=4806 lwp_id=583777 in Object.wait() [0x066ce000..0x066ce4f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <4c40a798> (a weblogic.kernel.ExecuteThread)
         at java.lang.Object.wait(Object.java:429)
         at weblogic.kernel.ExecuteThread.waitForRequest(ExecuteThread.java:94)
         - locked <4c40a798> (a weblogic.kernel.ExecuteThread)
         at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:118)
    "ExecuteThread: '1732' for queue: 'default'" daemon prio=10 tid=01ecd7d8 nid=4801 lwp_id=583771 in Object.wait() [0x065cc000..0x065cc4f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <4c40a808> (a weblogic.kernel.ExecuteThread)
         at java.lang.Object.wait(Object.java:429)
         at weblogic.kernel.ExecuteThread.waitForRequest(ExecuteThread.java:94)
         - locked <4c40a808> (a weblogic.kernel.ExecuteThread)
         at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:118)
    "ExecuteThread: '1731' for queue: 'default'" daemon prio=10 tid=05733d08 nid=4798 lwp_id=583766 in Object.wait() [0x067d0000..0x067d04f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <4c40a878> (a weblogic.kernel.ExecuteThread)
         at java.lang.Object.wait(Object.java:429)
         at weblogic.kernel.ExecuteThread.waitForRequest(ExecuteThread.java:94)
         - locked <4c40a878> (a weblogic.kernel.ExecuteThread)
         at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:118)
    ... (cut for brevity)
    "ExecuteThread: '2' for queue: 'default'" daemon prio=10 tid=009251b8 nid=172 lwp_id=569500 in Object.wait() [0x3d61f000..0x3d61f4f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <4a5b4498> (a weblogic.kernel.ExecuteThread)
         at java.lang.Object.wait(Object.java:429)
         at weblogic.kernel.ExecuteThread.waitForRequest(ExecuteThread.java:94)
         - locked <4a5b4498> (a weblogic.kernel.ExecuteThread)
         at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:118)
    "ExecuteThread: '1' for queue: 'default'" daemon prio=10 tid=00924ee8 nid=171 lwp_id=569499 in Object.wait() [0x3d6a0000..0x3d6a04f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <4a5b40f0> (a weblogic.kernel.ExecuteThread)
         at java.lang.Object.wait(Object.java:429)
         at weblogic.kernel.ExecuteThread.waitForRequest(ExecuteThread.java:94)
         - locked <4a5b40f0> (a weblogic.kernel.ExecuteThread)
         at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:118)
    "ExecuteThread: '0' for queue: 'default'" daemon prio=10 tid=00925050 nid=170 lwp_id=569498 in Object.wait() [0x3d7a2000..0x3d7a24f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <4a5b3d48> (a weblogic.kernel.ExecuteThread)
         at java.lang.Object.wait(Object.java:429)
         at weblogic.kernel.ExecuteThread.waitForRequest(ExecuteThread.java:94)
         - locked <4a5b3d48> (a weblogic.kernel.ExecuteThread)
         at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:118)
    "Thread-2" daemon prio=10 tid=00bec5f0 nid=18 lwp_id=569246 in Object.wait() [0x41e2e000..0x41e2e4f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <46c14ff0> (a com.wm.app.repov4.server.RepoServer$RepoLockTimeoutMgr)
         at com.wm.app.repov4.server.RepoServer$RepoLockTimeoutMgr.run(RepoServer.java:1533)
         - locked <46c14ff0> (a com.wm.app.repov4.server.RepoServer$RepoLockTimeoutMgr)
    "Thread-1" daemon prio=10 tid=00bec488 nid=17 lwp_id=569244 in Object.wait() [0x41eaf000..0x41eaf4f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <46c150a8> (a com.wm.driver.queue.data.DataQueue)
         at java.lang.Object.wait(Object.java:429)
         at com.wm.driver.queue.data.DataQueue.dequeue(DataQueue.java:310)
         - locked <46c150a8> (a com.wm.driver.queue.data.DataQueue)
         at com.wm.driver.queue.data.DataQueue.dequeueCommit(DataQueue.java:260)
         - locked <46c150a8> (a com.wm.driver.queue.data.DataQueue)
         at com.wm.driver.queue.data.DataQueue.dequeueCommit(DataQueue.java:254)
         - locked <46c150a8> (a com.wm.driver.queue.data.DataQueue)
         at com.wm.app.repov4.server.RepoServerBase$RepoEventManager.run(RepoServerBase.java:224)
    "Log Thread" prio=10 tid=00bec320 nid=16 lwp_id=569243 in Object.wait() [0x41f30000..0x41f304f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <46c15120> (a com.wm.util.sync.SimpleQueue)
         at com.wm.util.sync.SimpleQueue.deq(SimpleQueue.java:171)
         - locked <46c15120> (a com.wm.util.sync.SimpleQueue)
         at com.wm.util.sync.SimpleQueue.deq(SimpleQueue.java:126)
         - locked <46c15120> (a com.wm.util.sync.SimpleQueue)
         at com.wm.app.b2b.server.ServerLogHandler$LogThread.run(ServerLogHandler.java:268)
    "Cron Daemon" prio=10 tid=00bec1b8 nid=15 lwp_id=569241 in Object.wait() [0x41fb1000..0x41fb14f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <46c15190> (a java.util.Vector)
         at com.wm.util.Cron.run(Cron.java:424)
         - locked <46c15190> (a java.util.Vector)
         at java.lang.Thread.run(Thread.java:534)
    "Cron Daemon Pool2" prio=10 tid=00bec050 nid=14 lwp_id=569240 in Object.wait() [0x42032000..0x420324f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <46c15268> (a com.wm.util.pool.PooledThread)
         at java.lang.Object.wait(Object.java:429)
         at com.wm.util.pool.PooledThread.run(PooledThread.java:103)
         - locked <46c15268> (a com.wm.util.pool.PooledThread)
         at java.lang.Thread.run(Thread.java:534)
    "Cron Daemon Pool1" prio=10 tid=00bebee8 nid=13 lwp_id=569239 in Object.wait() [0x420b3000..0x420b34f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <46c152d0> (a com.wm.util.pool.PooledThread)
         at java.lang.Object.wait(Object.java:429)
         at com.wm.util.pool.PooledThread.run(PooledThread.java:103)
         - locked <46c152d0> (a com.wm.util.pool.PooledThread)
         at java.lang.Thread.run(Thread.java:534)
    "webMethods Integration Server" prio=10 tid=000870e0 nid=12 lwp_id=569238 in Object.wait() [0x42134000..0x421344f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <46c152f0> (a com.wm.app.b2b.server.Server)
         at java.lang.Object.wait(Object.java:429)
         at com.wm.app.b2b.server.Server.run(Server.java:353)
         - locked <46c152f0> (a com.wm.app.b2b.server.Server)
    "Signal Dispatcher" daemon prio=10 tid=00086f78 nid=7 lwp_id=569231 waiting on condition [0x00000000..0xffffffff]
    "Finalizer" daemon prio=10 tid=00086e10 nid=5 lwp_id=569229 in Object.wait() [0x4293b000..0x4293b4f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <46c15668> (a java.lang.ref.ReferenceQueue$Lock)
         at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:127)
         - locked <46c15668> (a java.lang.ref.ReferenceQueue$Lock)
         at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
         at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:188)
    "Reference Handler" daemon prio=10 tid=00086ca8 nid=4 lwp_id=569228 in Object.wait() [0x429bc000..0x429bc4f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <46c15340> (a java.lang.ref.Reference$Lock)
         at java.lang.Object.wait(Object.java:429)
         at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:120)
         - locked <46c15340> (a java.lang.ref.Reference$Lock)
    "main" prio=10 tid=00086b40 nid=1 lwp_id=569222 in Object.wait() [0x68ff3000..0x68ff24f0]
         at java.lang.Object.wait(Native Method)
         - waiting on <46c152f0> (a com.wm.app.b2b.server.Server)
         at java.lang.Thread.join(Thread.java:1001)
         - locked <46c152f0> (a com.wm.app.b2b.server.Server)
         at java.lang.Thread.join(Thread.java:1054)
         at com.wm.app.b2b.server.Server.start(Server.java:141)
         at com.wm.app.b2b.server.Main.main(Main.java:40)
         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
         at java.lang.reflect.Method.invoke(Method.java:324)
         at com.wm.proxy.Proxy.invokeStaticMethod(Proxy.java:166)
         at com.wm.app.server.ServerProxy.ServerMain_main(ServerProxy.java:77)
         at com.wm.app.server.ServerApp.start(ServerApp.java:105)
         at com.wm.app.Application.launch(Application.java:490)
         at com.wm.app.server.Main.main(Main.java:50)
    "VM Thread" prio=7 tid=000167f8 nid=3 lwp_id=569227 runnable
    "VM Periodic Task Thread" prio=8 tid=00016908 nid=11 lwp_id=569235 waiting on condition
    "Suspend Checker Thread" prio=10 tid=00016880 nid=6 lwp_id=569230 runnable

    We already opened a case. Actually, we did reproduce the problem: it happens because there is a hardware load balancing between the client and the WebLogic Server.
    As far as I know, EJB load balancing can be done only with WebLogic clusters. Could you confirm that ?

  • Spawning Threads inside the Web Container

    What are the ramifications of a developer spawning off threads from a "helper"
    object called from a servlet service() method ?
    Thanks in advance.

    That's what I said, it is not at all advisable but if you know what you
    are doing it can work just fine.
    The biggest issue is migration since the behavior is not defined in the
    spec and thus all vendors can implement it differently and it can change
    from version to version, which in turn defeats the J2EE portability
    advantage.
    That is why I highly recommended using JMX timers since it is going to
    be available on all J2EE servers and then the only vendor dependent
    thing is to get the MBeanServer.
    Dejan
    DN wrote:
    Hello
    I was also doing the same thing from my servlet but using another class which
    extends thread.
    I was using JDBC calls in the new thread , eventhough it worked fine I was getting
    warning messages in the console when I was using WSAD.(websphere studio).
    My app is deployed to WLS , i did not see any messages in WLS.
    When I post this issue in a forum , some one advised me that it is not advisable
    to open up threads from the servlets and this is what he said 'quote'
    so eventually (i.e.
    J2EE 1.4) spun threads from a Servlet accessing a
    database outside of a transaction will not be
    supported either.
    "Deyan D. Bektchiev" <[email protected]> wrote:
    Whit,
    If you are not careful you can very well starve the JVM, lose your
    security, transaction contexts and probably some other bad things I
    don't know about...
    But having said all those scary things, I must admit that we do it all
    the time and don't have any issues with that.
    For most purposes you should try to use the JMX timer service instead
    of
    spawning your own threads. You callback will be called in a different
    thread from the Weblogic thread pool and I guess this will be sufficient
    for most cases.
    Regards,
    Dejan
    Whit Armstrong wrote:
    What are the ramifications of a developer spawning off threads from
    a "helper"
    object called from a servlet service() method ?
    Thanks in advance.

  • Spawning Threads in WebLogic - forbidden in 5.1.  what about 6.x?

              Is spawning threads in 6.x permitted?
              http://websupport.beasys.com/websupport/clearexp_cgi/solution.htm?probdesc.objid=268519040
              

    I do not think it is forbidden, but certainly not recommended. In 5.1 using user
              threads was causing all sorts of problems ranging from memory leaks (caused by
              threadlocal implementation) to mysterious exceptions when ivoking EJBs etc.
              Threadlocal was fixed in 6, but still, you can never tell what will break if you
              try to invoke WebLogic services (EJBs etc) from user threads.
              You can use this trick to borrow threads from WebLogic execute threads pool:
              http://dima.dhs.org/misc/AsyncServlet.jsp
              Mike Reiche <[email protected]> wrote:
              > Is spawning threads in 6.x permitted?
              > http://websupport.beasys.com/websupport/clearexp_cgi/solution.htm?probdesc.objid=268519040
              Dimitri
              

  • Spawning thread in the stateful session bean

    I ran into an interesting issue: I am spawning a thread inside
    my stateful session bean's ejbCreate(...) method. The spawned
    thread runs in an infinite loop until some stop signal. The
    thread uses some BMP entity beans to access some data from DB,
    it creates some BMP entity beans as well as creates another
    stateful session bean in each iteration. The application ran
    into a crash. Now I have a couple questions:
    - First, is it an allowed operation to have a stateful session
    bean spawn off threads? Am I violating the specs?
    - Second, is it also allowed to have that thread create another
    bmp entity bean and another stateful session bean? Again, am I
    violating the specs also in here?
    Your responses will be very much appreciated.
    - Simon

    From the EJB 2.0 Spec, Section 24.1.2:
    <quote>
    These networking functions are reserved for the EJB Container.
    Allowing the enterprise bean to use these functions could compromise
    security and decrease the Container’s ability to properly manage the
    runtime environment.
    • The enterprise bean must not attempt to manage threads. The
    enterprise bean must not attempt to start, stop, suspend, or resume
    a thread; or to change a thread’s priority or name. The enter-prise
    bean must not attempt to manage thread groups.
    <quote>
    And, spawning threads in weblogic is highly discouraged in any
    server-side component. An application should not be designed this
    way.
    Bill
    Simon wrote:
    I ran into an interesting issue: I am spawning a thread inside
    my stateful session bean's ejbCreate(...) method. The spawned
    thread runs in an infinite loop until some stop signal. The
    thread uses some BMP entity beans to access some data from DB,
    it creates some BMP entity beans as well as creates another
    stateful session bean in each iteration. The application ran
    into a crash. Now I have a couple questions:
    - First, is it an allowed operation to have a stateful session
    bean spawn off threads? Am I violating the specs?
    - Second, is it also allowed to have that thread create another
    bmp entity bean and another stateful session bean? Again, am I
    violating the specs also in here?
    Your responses will be very much appreciated.
    - Simon

  • Shutting down a panel in one thread from another thread.

    For various reasons, I have a program with two threads (actually more than two, but only two are concerned here). One is the main panel that runs at startup, another is a Virtual O'Scope panel with a real-time display. Everything works more or less well, until it's time to exit the program.
    The main program starts by calling a routine to display the VO'scope; this routine calls CmtScheduleThreadPoolFunctionAdv to schedule the VOscope thread with the function VOscopePanelMain.
    VOscopePanelMain initializes things, displays the VOscope panel, and then calls RunUserInterface(); to process events in the VOscope panel.
    When it comes time to close the window, closing the panel (the X box in the upper right corner) triggers the panel callback CB_VoscopePanel, which processes the EVENT_CLOSE: event by calling QuitUserInterface(0); which, in turn, causes RunUserInterface to return to VOscopePanelMain, which then shuts things down, closes the panel properly, and exits. So far so good.
    int CVICALLBACK CB_VoscopePanel (int panel, int event, void *callbackData,
            int eventData1, int eventData2)
        int    iPanelHeight, iPanelWidth, iV2ControlLeft, iV2ControlWidth, iWidth,
            iT2ControlTop, iT2ControlHeight, iHeight, iLeft, iGap, iScreenTop, iScreenLeft,
            iTop, iBoxWidth;
        switch (event) {
            break;
        case EVENT_GOT_FOCUS: //happens when first displayed or refreshed
        case EVENT_PANEL_SIZE: //size the controls on the panel
           ... do stuff here;
            break;
        case EVENT_CLOSE:
            QuitUserInterface(0);  //stop VOscopePanelMain, which in turn closes the panel and cleans stuff up.
            break;
        return 0;
    However, I also want the panel to stop when I close the main program. The only way that I know how to do this cleanly is to have the main program (which has closed all of its panels and is in the process of shutting down) call VOSCOPE_Close_VOScope () which, in turn, calls CallPanelCallback (iHandle_VOscope, EVENT_CLOSE, 0, 0, 0); (which forces a call to CB_VoscopePanel above with the EVENT_CLOSE event), which should call QuitUserInterface, which should cause the RunUserInterface in VOscopePanelMain to return and let it continue to shut down. In addition, after calling CallPanelCallback, the shutdown routine calls CmtWaitForThreadPoolFunctionCompletion to wait for the VOscopePanelMain thread to actually quit and clean up before proceeding.
    But, of course, it doesn't since, and it took me a while to realize this. The call to QuitUserInterface isn't coming from inside of the VOscopePanelMain thread, it's coming from the main panel's thread - which is already in the process of shutting down. So, the main panel thread is telling itself to quit, VOscopePanelMain never gets the QuitUserInterface message, and things stall.
    So: how do I have one thread tell a panel in another thread to cleanly close? Or do I have to get complicated and either replace RunUserInterface in VOscopePanelMain with a loop that processes events manually and looks for a flag, or figure out something with a thread-safe queue? Any help appreciated.
    Attachments:
    Voscope.c ‏76 KB

    Sorry for delay in answering, it took me a while to find time to build up a working example.
    The attached program spawns a thread in a new thread pool and permit you to choose whether to close it from the main thread or the spawned thread itself.
    It appears that in such a minimal configuration the process works as expected. There may be some different configuration in your actual program that prevents this.
    Proud to use LW/CVI from 3.1 on.
    My contributions to the Developer Zone Community
    If I have helped you, why not giving me a kudos?
    Attachments:
    ThreadPoolWithGUI.zip ‏7 KB

  • Start a new thread from JSP ???

    suppose my JSP code is like this,
    <%
    Obj.heavyProcess();
    %>
    How can I start a new thread to do
    out.println(" ");
    out.flush("");
    while the heavyProcess is going on? I need to do this because my ISP will cut any Idle connection after certain time and my heavyProcess takes a long time to finish.
    for certain reasons, I can not do waiting page, refreshing, etc.

    The same way as you would from a normal java application. Write your thread class
    package com.yourpkg;
    public class YourHeavyProcess implements Runnable{
       private YourObject obj;
       public YourHeavyProcess(YourObject obj){
                this.obj = obj;
       public void run(){
           obj.heavyProcess();
    }and create and invoke this thread from your jsp.
    <%
            YourObject obj = new YourObject();
            Thread t = new Thread(new YourHeavyProcess(obj));
            t.start();
    %>
    out.println()..;
    out.flush()....;Note that the thread cannot write anything to the output stream as the response is over and done with. It can only perform backend tasks (like data archival for instance)
    You could consider using a Timer and a TimerTask class which provides a slightly higher abstraction layer over threads . Look at [url http://forum.java.sun.com/thread.jspa?threadID=758874]this  post (reply 48) for an example.
    And finally you wouldnt want a large number of threads to be generated and competing for cpu time on your web server (whose primary responsibility is to receive http requests and send responses). You can use a thread pool to manage the number of threads spawned by your application. If you use java5, take a look at the [url http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/Executors.html]java.util.concurrent.Executor class for thread pool implementations that you can use off the shelf.
    cheers,
    ram.

  • Hi Dude,     I ve seen all the threads from first to last even am gonna geta iphone 4s from Thailand. Would like to know which sim will be working fine in chennai as you all are using d phone for past many days???  Is it advisable to buy a phone

    Hi Dude,
    I ve seen all the threads from first to last even am gonna get a iphone 4s from Thailand. Would like to know which sim will be working fine in chennai as you all are using d phone for past many days???  Is it advisable to buy a phone from abroad.

    Thanks for that. Much more constructive than the last comment. It's only the restriction code I can't recall, not the access passcode. So I can currently access the device, just not age restricted content. Does that's make a difference? I also wondered if anyone knew how many attempts you get to try to get it right. Now tried 21 times and so far nothing bad has happened but I am concerned I'll eventually be completely locked out of the device. That doesn't seem in the spirit of things though. Surely it's foreseeable that a child could repeatedly try to guess the code so I can't see that it would be right to lock the device down completely in that circumstance, particularly if the access code is being typed in correctly every time.
    Thanks

  • Calling a delegate on the UI thread from a work thread inside a child class.

    Hi All,
    I've run into a snag developing a WPF multithreaded app where I need to call a method on the UI thread from my work thread, where the work thread is running a different class.
    Currently I am trying to use a delegate and an event in the 2nd class to call a method in the 1st class on the UI thread. This so far is not working as because the 2nd class is running in its own thread, it causes a runtime error when attempting to call
    the event.
    I've seen lots of solutions referring to using the dispatcher to solve this by invoking the code, however my work thread is running a different class than my UI thread, so it seems the dispatcher is not available?
    Below is as simplified an example as I can make of what I am trying to achieve. Currently the below code results in a "The calling thread cannot access this object because a different thread owns it." exception at runtime.
    The XAML side of this just produces a button connected to startThread2_Click() and a label which is then intended to be updated by the 2nd thread calling the updateLabelThreaded() function in the first thread when the button is clicked.
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    using System.Windows;
    using System.Windows.Controls;
    using System.Windows.Data;
    using System.Windows.Documents;
    using System.Windows.Input;
    using System.Windows.Media;
    using System.Windows.Media.Imaging;
    using System.Windows.Navigation;
    using System.Windows.Shapes;
    using System.Windows.Threading;
    using System.Threading;
    namespace multithreadtest
    public delegate void runInParent();
    public partial class MainWindow : Window
    public MainWindow()
    InitializeComponent();
    threadUpdateLabel.Content = "Thread 1";
    private void startThread2_Click(object sender, RoutedEventArgs e)
    thread2Class _Thread2 = new thread2Class();
    _Thread2.runInParentEvent += new runInParent(updateLabelThreaded);
    Thread thread = new Thread(new ThreadStart(_Thread2.threadedTestFunction));
    thread.Start();
    public void updateLabelThreaded()
    threadUpdateLabel.Content = "Thread 2 called me!";
    public class thread2Class
    public event runInParent runInParentEvent;
    public void threadedTestFunction()
    if (runInParentEvent != null)
    runInParentEvent();
    I'm unfortunately not very experienced with c# so I may well be going the complete wrong way about what I'm trying to do. In the larger application I am writing, fundamentally I just need to be able to call a codeblock in the UI thread when I'm in a different
    class on another thread (I am updating many different items on the UI thread when the work thread has performed certain steps, so ideally I want to keep as much UI code as possible out of the work thread. The work threads logic is also rather complicated as
    I am working with both a webAPI and a MySQL server, so keeping it all in its own class would be ideal)
    If a more thorough explanation of what I am trying to achieve would help please let me know.
    Any help with either solving the above problem, or suggestions for alternative ways I could get the class in the UI thread to do something when prompted by the 2nd class in the 2nd thread would be appreciated.
    Thanks :)

    If I follow the explanation, I think you can use MVVM Light messenger.
    You can install it using NuGet.
    Search on mvvm light libraries only.
    You right click solution in solution explorer and choose manage nugget...
    So long as you're not accessing ui stuff on these other threads.
    using GalaSoft.MvvmLight.Messaging;
    namespace wpf_Tester
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    public MainWindow()
    InitializeComponent();
    Messenger.Default.Register<String>(this, (action) => ReceiveString(action));
    private void ReceiveString(string msg)
    MessageBox.Show(msg);
    Dispatcher.BeginInvoke((Action)delegate()
    tb.Text = msg;
    private void Button_Click(object sender, RoutedEventArgs e)
    Task.Factory.StartNew(() => {
    Messenger.Default.Send<String>("Hello World");
    What the above does is start up a new thread - that startnew does that.
    It sends of message of type string which the main window has subscribed to....it gets that and puts up a message box.
    The message is sent from the window to the window in that but this will work across any classes in a solution.
    Note that the receive acts on whichever thread the message is sent from.
    I would usually be altering properties of a viewmodel with such code which have no thread affinity.
    If you're then going to directly access properties of ui elements then you need to use Dispatcher.BeginInvoke to get back to the UI thread.
    I do that with an anonymous action in that bit of code but you can call a method or whatever instead if your logic is more complicated or you need it to be re-usable.
    http://social.technet.microsoft.com/wiki/contents/articles/26070.aspx
    Hope that helps.
    Technet articles: Uneventful MVVM;
    All my Technet Articles

  • Calling a thread from a cvi code file to another code file

                Hello, 
                I want to call a thread from a labwindows/cvi code file to another labwindows/cvi code file. Namely, my thread function (GraphLoop) is in 'TestsModel.c' ; but I will call the thread in 'Tests.c' .  My code in 'Tests.c' is in the following;
    int CVICALLBACK GraphLoop (void *functionData);
    int GraphLoopId;
    int callbackDataGraphLoop;
    int CVICALLBACK CBBasla (int panel, int control, int event,
    void *callbackData, int eventData1, int eventData2)
    switch (event)
    case EVENT_COMMIT:
    CmtInstallThreadPoolCallback (poolHandle, EVENT_TP_THREAD_BEGIN, GraphLoop, callbackDataGraphLoop, GraphLoopId);
    if (tiklandiE3631ACihazinaBaglan == 0 && tiklandi34401ACihazinaBaglan == 0) // 'E3631A Cihazına Bağlan' ve '34401A Cihazına Bağlan' tuşlarına basılmamışsa uyarı verir.
    MessagePopup ("Uyarı", "Lütfen cihaz bağlantısını kontrol ediniz.");
    else
    if (tiklandiKaydet == 0)
    MessagePopup ("Uyarı", "Lütfen ayarları kaydediniz.");
    else
    SetCtrlAttribute (Testler, PnlTestler_BASLA, ATTR_DIMMED, 1); // 'Başla' tuşunu pasif hale getirir.
    SetCtrlAttribute (Testler, PnlTestler_BASLA, ATTR_DISABLE_PANEL_THEME, 1); // 'Başla' tuşunun etiketini pasif hale getirir.
    SetCtrlAttribute (Testler, PnlTestler_BITIR, ATTR_DIMMED, 0); // 'Bitir' tuşunu aktif hale getirir.
    SetCtrlAttribute (Testler, PnlTestler_BITIR, ATTR_DISABLE_PANEL_THEME, 0); // 'Bitir' tuşunun etiketini aktif hale getirir.
    CmtNewThreadPool (DEFAULT_THREAD_POOL_HANDLE, &poolHandle); //Yeni bir thread oluşturur.
    CmtScheduleThreadPoolFunction (poolHandle, GraphLoop, NULL, &GraphLoopId); // GrapLoop thread fonksiyonunu başlatır.
    break;
    case EVENT_RIGHT_CLICK:
    break;
    return 0;
              I take that errror after executing this code;
      error:Undefined symbol '_GraphLoop' referenced in "f:\Tests.obj"
             Please, can you help me for my question?
             Regards...

    Hello Eren,
    I assume this is a link error.
    Do you have TestsModel.c file included in your project?
    Constantin.

  • Multiple message threads from same person

    I have multiple message threads from the same person in messages on my iPhone and iPad. One comes from their phone number and one from their email. Here are all the details, I would love to be able to combine them into one thread.
    This other person and myself each have a new MacBook Pro, iPad Air 2, I have an iPhone 6 and they have an iPhone 5S. They are all updated with the most recent system software.
    On my MacBook Pro, the conversations that are split on my iPhone and iPad are not split. On the MacBook Pro, all of the texts from both conversations are appearing in one. In my contacts which are syncing with iCloud I have both the phone number and email address of this other person.
    I have messages set up on all of my devices to send and receive from my phone number and my email, start new conversations is from my phone number. This other person has it set up the exact same way on all of their devices.
    So why when I text this person from one conversation thread and they respond it comes through to the other conversation thread?
    Why can't I seem to join these two conversations when everything is set up the way it should be and they ARE joined on my MacBook Pro but not my iPhone and iPad?

    She kept the same number on her new phone, but now there are 2 conversation threads. A new one started with messages sent from the new phone, the old phone should be out of service now. Why didn''t  messages sent by the new phone resume in the same conversation? I assume because it's a different IMEI.  But now whenever I use her  phone number to create a new message, it goes in the old IMEI*'s conversation thread and is therefore not delivered. It's in green so it thinks it's an SMS also not a iMessage device.
    If I want to send a message correctly  to the new phone, I have to make sure I  go into the correct newer thread and enter it there,
    For your second answer, the person is receiving the message but the thread now says "email address", not the person's name in the contact list. The sender is sending to the person's phone number, not her email address.

  • How to terminate a java thread from c++ code?

    Hi,
    I made a screensaver which loads a jvm, forks a thread running a java class, wait until user's action(i.e. mouse move/click keyboard input), then terminate the java thread.
    However, I met a problem, How to terminate a running java thread from c++ code?
    Here is my code, but it does not work: (even after the terminate is called, jvm throws an error)
    JNIEnv* env;
    JavaVM* jvm;
    HANDLE hThread; //handle for the startThread
    unsigned __stdcall startThread(void *arg)
         jclass cls;
         jmethodID mainId;
         jint          res;
         int threadNum = (int)arg;
         res = jvm->AttachCurrentThread((void**)&env, NULL);
    cls = env->FindClass( MAIN_CLASS);
         mainId = env->GetStaticMethodID(cls, "main", "([Ljava/lang/String;)V");
         // setup the parameters to pass to main()
         jstring str;
         jobjectArray args;
         int i=0;
         args = env->NewObjectArray(1, env->FindClass("java/lang/String"), 0); //only one input parameters
         str = env->NewStringUTF("localhost");
         env->SetObjectArrayElement(args, 0, str);
         env->CallStaticVoidMethod(cls, mainId, args); // call main()      
         if (env->ExceptionOccurred()) {
                   env->ExceptionDescribe();
         return TRUE;
    Here is the main method:
    First create the jvm and load the thread. then tries to terminate the thread, but failed here
    switch (msg)
    { case WM_CREATE:
              JavaVMOption options[NUMBEROFOPTIONS];
              JavaVMInitArgs vmargs;     
              jint rc;
              vmargs.version = JNI_VERSION_1_4; /* version 1.4 */
              vmargs.options = options;
              vmargs.nOptions = NUMBEROFOPTIONS;
              vmargs.ignoreUnrecognized = JNI_FALSE;          
              rc=JNI_CreateJavaVM( &jvm, (void **)&env, &vmargs ); /* create JVM */
              /* We pass the thread number as the argument to the invoked thread */
              unsigned int threadId = -1;
              // to initialize a thread-safe C runtime library
              hThread = (HANDLE)_beginthreadex(NULL, 0, &startThread, NULL, 0, &threadId );
    } break;
    case (WM_DESTROY):
              CloseHandle( hThread );
              jvm->DestroyJavaVM(); /* kill JVM */
              Debug("Destroy Java Virtual Machine\n");
    }break;
    Note, after the thread "startThread" runs, it has an infinite loop and will not terminate, until the user clicks to terminate.(I didn't call jvm->DetachCurrentThread();_endthreadex(0); in the "startThread" because the java thread will not terminate by itself)
    Thus, the only way to terminate the thread is to call closehandle(hthread) in the main thread, which may cause jvm to throw an error.
    Do you know how to terminate a java thread safely???
    Thanks a lot

    Assuming that your java thread is in a loop of some kind. Such as
    int i=1; /* I tried using a boolean, I just could not get my C++ env, to change this value. So i decided to use an int */
    run {
    while(i)
    isdfjsdfj
    void seti()
    i=0
    So, B/4, i call destroyVM in my C++ code, i call this seti(). so the loop terminates, therefore my thread finishes executing and ends.
    Hope this helps
    tola.

  • Enable spawn pages from template

    Hi all,
    I have a fill-in PDF form (created in Acrobat Pro X) that uses a javascript button to duplicate pages (spawn pages from template).  We got a trial version of LC Reader Extensions ES in order to enable the button to function in Reader.  The problem is, as I understand it, when our evaluation period runs out, the button will stop working in Reader.  Is this true?  The form will be distributed to LESS THAN 500 people- we just want this button to work for everyone.  Is there another way to enable users of Reader to spawn pages from template?
    I don't believe that purchasing the software is an option, as the Adobe Rep on the phone said it would be $10,000 per form. Any help is greatly appreciated.
    Thanks!

    Sorry, but the functionality you are looking for is not available with the limited Reader Eextensions capability available within Acrobat.  Reader Extensions has a set of rights, and the following rights are available only through the server product (LiveCycle Reader Extensions).  These specific rights are:
    2 - Form Data Import/Export
    5 - Spawn Pages from templates (for PDF page forms, as opposed to XFA dynamic forms)
    9 - Barcoded form data unencrypted
    10 - Browser-based annotations (note that this capability is being deprecated for use with Reader)
    11 - Web services or ODBC access from the form
    12 - Embedded File actions
    [Acrobat enables basic form fillin, signatures, and annotations, as well as the ability to save the document after the data fillin or action has been done]
    In your case, you either need to get a LiveCycle Reader Extensions license or move yourself to LiveCycle Designer-based forms where dynamic forms may do what you'd like.
    I'd suggest a deeper discussion with your salesperson.

  • Open Threads from UIX Forum?

    I've got a couple of threads on which I was still hoping for responses over on the UIX forum. I can't update them there, and it says current threads will be 'moved' here. Does that mean the existing content of the threads will literally be moved over here, or just that followups will be posted here? If I want to update a UIX thread, should I start a new one here, or how soon could I expect my open threads from there to be continued here?

    I'd just start a new one here and include a URL to the old one in case anyone needs to see the full context.
    Rob
    Team JDev

Maybe you are looking for