Thread conceptual problem

Hi there;
I have a stream from which I get data continuously, in an ordered fashion. I have a thread opened other than the main thread to listen to the stream. After I get a portion of data, I send this data to a module with a lock on the module to process it appropriately in the same thread. But then the operation of this module takes too long that I cannot receive data, actually miss some data on the stream since I am waiting for the module to complete its operation.
How can I resolve the problem of missing the data, should I open new threads, if so where?
Thanks a lot
Melis

Melis,
Just a thought. You create another thread inside this thread which can process the data; For example
Main Thread contains ThreadOne which recieve the data from continous Stream. Now ThreadOne wants to call the module to process the data which takes long time ( causes you to miss data which comes in from the Stream) Create ThreadTwo inside the ThreadOne to work with the module; ThreadOne is free now. Another stream comes in so the ThreadOne is ready and Create ThreadThree to take care of it ( ThreadOne delegate the work with module to newly created threads to do the job; ThreadOne is not interested in working with the module anymore)
You will need to coordinate the locking between these newly created thread. If the lock is acquired by the ThreadTwo on the module, Thread Three has to wait and when ThreadTwo finishes, it calls for TreadThree to start so that ThreadThree acquire the lock on the module or whoever is in queue waiting and get the chance to acquire the lock ( OS who decides who is next to wake up.
Let me know what do you think.
Regards,
Alan Mehio
London, UK

Similar Messages

Conceptual problem: AJAX Memory tree for navigation

Hello,
I have a conceptual problem with a navigation tree.
I have to implement a AJAX memory tree for navigation purposes, which should be on page 0, so this tree is on the left side of every page.
Therefore I searches some examples and found this: http://www.oracle.com/technology/pub/articles/spendolini-tree.html
So I try to rebuild this example with my custom tables and recognised that this example is very slow. I have round about 100 nodes in the tree and my database and network connection is extremly fast(I`m sitting in a proffesional data center).
So first of all I am wondering why the tree is so slow when I try to expand it and if it is possible to use this tree on the page 0.
Because of the performance problem I searched for some alternatives, but I didn`t found one.
Every custom APEX-tree is not dynamic(AJAX) and the dynamic APEX-lists can not base on a select-statement.
So at this moment I don`t know how to build a AJAX memory tree for navigation which is fast, looks good and works as expected.
Does anybody have an idea why the tree is so slow?
Are there alternatives which I can try to use?
Thank you,
Tim

Hi Tim
100 nodes is not a lot of data for a tree, so why bother with AJAX at all.
Just render the entire tree, and let the user expand and collapse nodes as they like.
APEX has a dhtml tree in the standard themes which is enough to get you started.
The issue I had with it is that it isn't stateful, so doesn't remember which nodes are open between page refreshes.
That's what got me into ExtJS originally.
If you look at my demo, I have a couple of examples worth looking at:
- [tree using APEX lists|http://apex.oracle.com/pls/otn/f?p=200801:2025:0::NO:::] uses APEX built in hierarchical lists, which allows conditional logic on nodes
- [AJAX editable tree|http://apex.oracle.com/pls/otn/f?p=200801:2013:0::NO:::] which is fully AJAX enabled.
The other point worth mentioning is if you are using hierarchical queries for your tree you should consider restructuring your data set.
Typically trees are fairly static, in that the data changes very little over time.
This makes a very strong case for maintaining the node sequence and level in a denormalised way.
Data updates become more expensive, but read operations, which will be the bulk of your operations will be very fast.
Many choices on how to implement, e.g. materialized views with refresh on demand.
Regards
Mark
[Random Insights into Oracle|http://oracleinsights.blogspot.com/] | [Marks Playpen|http://apex.oracle.com/pls/otn/f?p=200801]

Java Threads compilation problem

Hi everyone,
I've having problems getting a simple thread program to compile, the programs says " ; " expected when there is already one present. I've gone through the program many times and still can't put my finger on whats going wrong. If someone could take a quick look and if possible tell me where I am going wrong.
Many Thanks
Its class ThreadA that will not compile
***code********************************************
public class ThreadA extends Thread
private int id;
public ThreadA(int i) (id = i);
public void run()
for (int i=0}; i < 10; i++);
try {sleep(1000};)catch (InterruptedException e)();
System.out.println("Output from Thread " + id);
import java.io.*;
public class TestThreads1
public static void main (String args [] )
Thread t1 = new ThreadA (1);
Thread t2 = new ThreadA (2);
Thread t3 = new ThreadA (3);
t1.start();
t2.start();
t3.start();
**code***********************************************************

public class ThreadA extends Thread
private int id;
public ThreadA(int i) (id = i); // <-- problem
public void run()
for (int i=0}; i < 10; i++); // <-- two problems
try {sleep(1000};)catch (InterruptedException e)(); // <-- more problems
System.out.println("Output from Thread " + id);
}

64-bit JNI C++ to JAVA invocation multiple threads classloader problem

Hi ALL,
I have a C++ app that invokes Java classes on 64-bit Solaris 10 with 64-bit JVM.
Here is the problem:
The native non-main (not the thread that initializes the JVM) threads would not be able to find any user-define class.
Here are the symptoms and observations:
1. JNIEnv::ExceptionDescribe() showed the following StackOverflowError:
Exception in thread "Thread-0" java.lang.StackOverflowError
 at java.util.Arrays.copyOf(Arrays.java:2734)
 at java.util.Vector.ensureCapacityHelper(Vector.java:226)
 at java.util.Vector.addElement(Vector.java:573)
 at java.lang.ClassLoader.addClass(ClassLoader.java:173)
 at java.lang.ClassLoader.defineClass1(Native Method)
 at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
 at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
 at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
 at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
 at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
 at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
 at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)2. The "main thread" that instantiates the JVM has no problem finding and loading any class or method
3. But the other threads (non-main threads) would not be able to find the user-defined classes unless the classes were already loaded by the main thread.
4. The non-main threads can find the "standard" java classes with no problem
5. The same app ran fine on 32-bit system.
6. Except for the JVM reference is global, each thread acquired JNIEnv by either GetEnv() or AttachCurrentThread().
Any idea why it is a problem with 64-bit?
I have the sample program to reproduce this issue in this thread: http://forums.sun.com/thread.jspa?messageID=10885363&#10885363. That was the original thread I raised but I have narrowed it down to a more concrete scenario. That's why I am creating this new thread. I hope this does not break any rule on this forum. If it does, I apologize.
I really appreciate it if anyone can provide any help/suggestion.
Regards,
- Triet

Here is the sample program. Again, this works on 32-bit but not 64-bit.
#include <string>
#include "jni.h"
#include "TestThread.h"
static JavaVM *g_pjvm = NULL; /* denotes a Java VM */
static JNIEnv *g_penv = NULL; /* pointer to native method interface */
void initJVM(char** jvmOptions) {
 printf("RJniTest init starts...\n");
 JavaVMInitArgs vm_args; /* JDK/JRE 6 VM initialization arguments */
 JavaVMOption* poptions;
 int optionLen = 0;
 while (jvmOptions[optionLen]) {
 optionLen++;
 printf("RJniTest::init len=%d\n", optionLen);
 if (optionLen > 0) {
 printf("RJniWrapper::init jvmOptions\n");
 poptions = new JavaVMOption[optionLen];
 //poptions[0].optionString = "-Djava.class.path=/usr/lib/java";
 int idx = 0;
 while (jvmOptions[idx]) {
 poptions[idx].optionString = jvmOptions[idx];
 idx++;
 printf("RJniTest::init vm_args: version(%x), nOptions(%d)\n",
 JNI_VERSION_1_6, optionLen);
 vm_args.version = JNI_VERSION_1_6;
 vm_args.nOptions = optionLen;
 vm_args.options = poptions;
 vm_args.ignoreUnrecognized = JNI_FALSE;
 // load and initialize a Java VM, return a JNI interface
 // pointer in env
 printf("RJniTest::init creates JVM\n");
 JNI_CreateJavaVM(&g_pjvm, (void**)&g_penv, &vm_args);
 printf("RJniTest init ends\n");
void findClass(const char* classname) {
 static const char* fname = "justFindClasses";
 printf("%s: findClass: %s\n", fname, classname);
 JNIEnv* jenv;
 jint ret = g_pjvm->GetEnv((void**)&jenv, JNI_VERSION_1_6);
 if (ret == JNI_EDETACHED) {
 ret = g_pjvm->AttachCurrentThread((void**)&jenv, NULL);
 if (ret != JNI_OK || jenv == NULL) {
 printf("%s: get env error: ret=%d\n", ret, fname);
 } else {
 printf("%s: got new env\n", fname);
 } else if (ret == JNI_OK) {
 printf("%s: env already there\n");
 jclass classref;
 classref = jenv->FindClass(classname);
 if (classref == NULL) {
 printf("%s: %s class not found!\n", fname, classname);
 if (jenv->ExceptionOccurred()) {
 jenv->ExceptionDescribe();
 jenv->ExceptionClear();
 printf("%s: found class: %s\n", fname, classname);
class RJniTestThread : public TestThread {
public:
 void threadmain();
void RJniTestThread::threadmain() {
 printf("RJniTestThread::threadmain: Starting testing\n");
 findClass("org/apache/commons/logging/Log");
 findClass("java/util/List");
 printf("RJniTestThread::threadmain: done.\n");
int main(int argc, char** argv) {
 char **jvmOptions = NULL;
 printf("RJniTestDriver starts...\n");
 if (argc > 1) {
 jvmOptions = new char*[argc];
 for (int i = 0; i < argc ; i ++) {
 jvmOptions[i] = argv[i + 1];
 jvmOptions[argc - 1] = NULL;
 } else {
 int size = 8;
 int i = 0;
 jvmOptions = new char*[size];
 jvmOptions[i++] = (char*) "-Djava.class.path=<list of jar files and path here>";
 jvmOptions[i++] = (char*) "-Djava.library.path=/sandbox/mxdev/3rdparty/java/unix/jdk1.6.0_14/jre/lib/sparc";
 jvmOptions[i++] = (char*) "-Djava.compiler=NONE";
 jvmOptions[i++] = (char*) "-verbose:jni";
 jvmOptions[i++] = (char*) "-Xcheck:jni";
 jvmOptions[i++] = NULL;
 printf("init JVM\n");
 initJVM(jvmOptions);
 // UNCOMMENT HERE
 // findClass("org/apache/commons/logging/Log");
 // findClass("java/util/List");
 // UNCOMMENT END
 printf("start test thread\n");
 RJniTestThread testThread;
 ThreadId tid = testThread.launch();
 printf("wait for test thread\n");
 int ret = pthread_join(tid, NULL);
 printf("RJniTestDriver ends\n");
}

Conceptual problem in using a PCI-6602?

Hi, All You Wild and Crazy NI/LabVIEW Types --
I have a problem that's been close to sending me off the deep end for more than a month now, and I think that I'm so enmeshed in it that I can't see the forest for the trees anymore. I'd like to apologize in advance for the length of this post, but there are some details that might or might not be important, and I'd rather make the mistake of giving you too much information than not enough.
We do impact-cratering experiments, using a gun to launch (usually) spherical projectiles at a variety of targets. One of our big efforts is to measure the velocities at which material is ejected from growing craters. We do that with a line-generating laser, oriented so the "sheet" of laser light is perpendicular to the target's surface and through the impact point; we strobe the laser at a programmed rate (with our PCI-6259 board) and take a time exposure of the scene with a Nikon D100 DSLR. When target material -- usually grains of sand -- is ejected, the laser illuminates a "slice" through the curtain of ejecta, illuminating a small portion of the fragments numerous times in their trajectories. Since we know the scale of the photograph and its orientation relative to the laser's illumination, and we also know the rate at which the laser is flashing, we can easily calculate the velocities of the illuminated particles. I'm attaching a picture (file 4044, cropped.jpg) of an example taken with an older camera to give you an idea. In the picture, the laser's illuminating the scene from the right of the frame and the projectile flew into the picture from the top of the frame, traveling along the left-hand edge. The brightest portion is the flash from the impact, and the rest of the parabolic trajectories are the grains of sand in flight. The target bucket, full of coarse sand, is the elliptical looking cylinder at the bottom of the picture. It's roughly 28 cm in outside diameter, if you'd like a scale.
As you might imagine, with our projectiles moving anywhere between 0.7 and 3 km/s, sequencing everything is pretty important. We're using (or trying to use) LabVIEW to do all of the sequencing, instrument control, and data storage. Things are going pretty well so far, except for what I'll describe in more detail below. A couple more things, though, first. It's important that we measure the projectile's speed in each shot, as that controls impact energy and momentum, which are critical to know in a given experiment. We do that with simple laser-photodetector pairs (which we normally call "velocity stations") arranged along the projectile's trajectory. As the projectile passes between a laser and its detector, its shadow is detected and a TTL pulse is sent to our PCI-6602 board. Depending on the experiment, we use three or four such laser-dector pairs. They use counters 0, 1, 2, and 3. We know the distances between the laser stations and, once we get the times between detections, it's s simple matter to calculate the projectile's velocity.
We also use LabVIEW to fire the gun, and we do that because opening the camera's shutter has to be synchronized with the firing pulse, which currently is sent via P1.1 on the 6259. Here's the problem: when we test the laser-detector arrays in a "standalone" mode (that is, without any other tasks or operations being done with LabVIEW), they work infallibly. It's when we try to use LabVIEW to fire the gun that we get either very erratic results from the velocity stations/6602 or no results at all.
I've tried a range of things, from starting the two-edge measurement task before the firing signal is sent, to trying to force things with a timed sequence, to doing things with brute force via a seuqence structure. When I try to start the two-edge measurement task first, though, the firing signal isn't sent until the counters time out. This of course, wrecks the experiment, because all of the timing is then messed up. The VI that I've attached (Version 1.vi) is a HIGHLY simplified version of the initial attempt I made at doing this, with all sorts of background stuff removed just so I can cut to the chase. (Only one two-edge measurement task is shown, for instance.) I think that the VI is pretty self-explanatory (and embarrassingly primitive), so it probably doesn't need much in the way of explanation. Counter 7 and PFI 0 on the 6602 are used to accept the signal from the firing button and trigger the event structure, which contains the two-edge separation and gun-firing tasks. (In reality, I use a separate VI to have three to four concurrent two-edge separation tasks running concurrently, one for each velocity station.) I start the two-edge separation tasks first so the detectors and counters are ready for the projectile. It's not necessary here, but I kept the 500 ms wait frame in this example because that's why the sequence structure exists -- to allow the shutter of the Nikon to open completely before the gun fires. After those 500 ms, the firing signal is sent to the circuit that actually fires the gun.
What happens in this configuration is that the second frame of the sequence structure doesn't execute until the 5-s timeout transpires in the two-edge separation task. I've also tried this using a line on the 6602 to fire the gun instead of P0.1 on the 6259, but that ends up with the same result. (Both counters are used on the 6259 to strobe the main illumination laser, so they're unavailable, if you're wondering. In any case, we need four counters for the four velocity stations.)
FINALLY, my question: What am I doing wrong, here? If I put the two-edge separation tasks in the same frame of the sequence structure as the firing task, the gun fires when it's supposed to, but we get no velocity measurements. I've also tried to force the timing with another version of a sequence structure; I'm attaching another very simplified version below as Fire and speed example.vi.
After you recover from your violent fits of laughter, I'd really appreciate hearing what you might recommend. (And no, surrender isn't an option.)
Thanks for taking all of your valuable time to read this huge post -- I really appreciate it!
Mark
Attachments:
4044, cropped.jpg ‏197 KB
Version 1.vi ‏35 KB
Fire and speed example.vi ‏30 KB

I agree with all 3 of Kevin's points. His first suggestion will probably fix your problem (see below). The 2nd and 3rd suggestion would improve efficiency and responsiveness, but #2 might not be possible since independently triggering four outputs in hardware would require the use of 4 counters (on the 6602 anyway) which might be busy doing other tasks in your application (although if you don't need the stations to trigger independently then you could implement this with a single counter).
I think I have an explanation of the problematic behavior you are seeing based off of the following bits of information from your post:
1. Running the small example code by itself works flawlessly, but adding other simultaneous functionality fails. You mentioned you are doing this on 4 stations, so I'm assuming 4 counter input tasks running in parallel.
2. The behavior you are seeing is that the 2nd sequence does not execute until after the read times out (note that the sequence is supposed to be executing in parallel with the read).
It sounds like the problem is coming from a combination of calling into DAQmx Read before data is available (this consumes one of the threads that LabVIEW has allocated to your application until DAQmx Read finishes executing) along with the fact that LabVIEW allocates 4 threads per execution system per priority by default. Since all of your threads (from what I can tell) are executing on the same priority, the 4 reads you are calling will block anything else from executing until they have completed. By then it's too late and the firing of your gun happens after the counter task has already timed out.
You *may* increase the number of threads allocated to your application by using a VI that is included with LabVIEW (vi.lib\Utility\sysinfo.llb\threadconfig.vi) and this would also probably remedy the behavior you are seeing. However, rather than throwing more threads at this application I think the better solution would be to change the sequencing of your tasks like Kevin suggested ("create and start the 2-edge task before entering the sequence structure, and defer the 2-edge *reading* until *after* firing the DO")--in doing this you would now expect to see data immediately upon calling DAQmx Read and you avoid the situation where Read is blocking indefinitely and consuming an application thread. You could take this a step further by checking the Available Samples per Channel property (or using the DAQmx EveryNSamplesAcquiredIntoBuffer event) to ensure that data is actually available before calling Read.
Best Regards,
John Passiak

Error thread java : problem with the function "resume 0x***" (forum sun)

One problem with the function of jdb occured when I tried to use it to
pilot the processor with differents threads. In fact, I use a simple example with 2 threads.
I stop the two threads with two breakpoint, and I want to resume one or the other (with the function "resume 0x****"), the one wich I resumed stop again on the breackpoint and I decide again to resume one or the other. All of that to obtain a tree of execution.
I give you the code of the class and the code of jdb.
CLASS: (it's just a object Room with a variable degre that I increment and decrement with two threads increase and decrease)
public class Test{
     public static void main(String[] args){
          Room r = new Room();
          decrease de = new decrease(r);
          increase in = new increase(r);
          de.start();
          in.start();
class Room {
     private volatile int degre=20;
     public void more(){
     degre += 4;
     public void less(){
     degre -= 3;
class decrease extends Thread{
private Room room;
public decrease(Room r){
          room =r;
public void run(){
try{
     while (!interrupted()){
          room.less();
catch(InterruptedException e) {}
class increase extends Thread{
private Room room;
public increase(Room r){
     room =r;
public void run(){
     try{
          while (!interrupted()){
               room.more();
catch(InterruptedException e) {}
JDB:
Initializing jdb ...
stop at Test:7Deferring breakpoint Test:7.
It will be set after the class is loaded.
runrun Test
Set uncaught java.lang.Throwable
Set deferred uncaught java.lang.Throwable
>
VM Started: Set deferred breakpoint Test:7
Breakpoint hit: "thread=main", Test.main(), line=7 bci=30
7 in.start();
main[1] stop at room:16
Set breakpoint room:16
main[1] stop at room:20
Set breakpoint room:20
main[1] resume
All threads resumed.
>
Breakpoint hit: "thread=Thread-0", room.less(), line=20 bci=0
20 degre -= 3;
Thread-0[1] threads
Group system:
(java.lang.ref.Reference$ReferenceHandler)0x10d Reference Handler cond. waiting
(java.lang.ref.Finalizer$FinalizerThread)0x10c Finalizer cond. waiting
(java.lang.Thread)0x10b Signal Dispatcher running
Group main:
(decrease)0x146 Thread-0 running (at breakpoint)
(increase)0x147 Thread-1 running (at breakpoint)
(java.lang.Thread)0x148 DestroyJavaVM running
Thread-0[1] resume 0x147
Thread-0[1]
Breakpoint hit: "thread=Thread-1", room.more(), line=16 bci=0
16 degre += 4;
Thread-1[1] resume 0x147
Thread-1[1]
Breakpoint hit: "thread=Thread-1", room.more(), line=16 bci=0
16 degre += 4;
Thread-1[1] print degre
degre = 24
Thread-1[1] resume 0x146 //It's here the problem, thread 0x146 have to stop on the //next breakpoint of decrease but nothing happen
Thread-1[1] resume 0x147
Thread-1[1]
Breakpoint hit: "thread=Thread-1", room.more(), line=16 bci=0
16 degre += 4;
Thread-1[1] clear
Breakpoints set:
breakpoint Test:7
breakpoint room:16
breakpoint room:20
PS: I tried many other examples with other class and other kind of breakpoints, but, in any cases, on thread doesn't manage to resume. When I try with general resume (no specification of the thread), It works but it isn't interresting for me because I want to decide wich thread continue his execution.

Hi,
I have read the FAQ of the JMF.
The problem was the jar files of the JMF were not in the JRE\BIN\EXT
folder of the Java runtime!
now it works!
thanks
Reg

Killing a thread ( runnable ) - problem

Hi,
I already posted about this, and got a good answer.
But, I still have a probalem :
Here is a piece of my code :
// this is the bean which is in the EPN and I want it to create a thread that prints something :
public class EventListener implements StreamSink,com.bea.wlevs.ede.api.DisposableBean ,InitializingBean {
// the relevant methods:
RunnableTestBean runnableTestBean; // this is the thread which suppose to print ..
public void destroy() throws Exception {
          System.out.println("destroydestroydestroydestroydestroydestroydestroy");
          runnableTestBean.suspend();
     public void afterPropertiesSet() throws Exception {
          runnableTestBean=new RunnableTestBean();
          runnableTestBean.run();
          //System.out.println("afterPropertiesSetafterPropertiesSetafterPropertiesSet");
and the class RunnableTestBean :
public class RunnableTestBean implements RunnableBean {
     boolean stopped=false;
     public void run() {
          while ( !stopped){
               System.out.println(" printing...");
               try {
               wait(5000);
                    //Thread.sleep(1000);
               } catch (InterruptedException e) {
                    System.out.println(" Stoping thread ??");
                    e.printStackTrace();
     public void suspend() throws Exception {
          stopped=true;
The thing is that when I use the method as above :
public void run() {
          while ( !stopped){
               System.out.println(" printing...");
               try {
               wait(5000);
                    //Thread.sleep(1000);
               } catch (InterruptedException e) {
                    System.out.println(" Stoping thread ??");
                    e.printStackTrace();
When I undeploy the application , the destoy method ( in EventListener class ) is not called !
but,
if I implement the run "run" method like this :
public void run() {
System.out.println(" Something ");
than everything is fine!
The differrence as you can see , is that when I use an infinite loop - the destroy method never called ( seems that the caller waits for it to stop , and that's why the
destroy method not called )
When i don't use the infinaie loop- it's OK.
So, any help ?
Thanks ..

Looking at the code that you have posted, the problem is that you are calling runnablebean.run() method in afterPropertiesSet (instead of starting a thread in which the run method is called). So, it looks like it will get stuck in afterPropertiesSet for ever.
The recommended approach for what you are trying to do is to make the EventListener class implement RunnableBean (instead of having a separate class that implements RunnableBean that gets called from afterPropertiesSet). This means that at application startup time, this EventListener's run() method will be called by OCEP framework code in a separate thread. You can still use the suspend() method to stop the thread similar to how you are doing in your code now.

Nokia 603 SMS thread view problem

Hi All, My nokia 603 is unable to display the message in thread view. whenever the SMS is sent or recieved it will show some random integers. but if i enter to the folder view I am able to view the entire message. This is happening all of a sudden without any change done in the phone. Some one pls clarify whether it is the known issue, if so please gimme the solution. Thanks, Muralids

Hi muralids,
Thank you for your post.
We haven't confirmed if this is a known bug as it's not included in the list of Nokia 603 reported issues posted here: Firmware change logs for Symbian (S60) devices.
However, you may try these troubleshooting steps to fix the problem:
1. Check if the conversation view is still activated. Go to Menu, tap on Messaging, and then hit Options ( ≡ ). After that, choose View folders, hit Options ( ≡ ) again, and then select Message View. Set it to Conversations View.
2. If the first option didn't work, try the steps provided in this link: Nokia 603 - Need help in fixing a problem?
Hope this information helps. Cheers!

Thread Problem - (Thread Blocking Problems?)

Hi Friends
In my program while using thread i found a problem in this code .
In this whlie running the 'msg' was printen only after all 5 inputs are given .
why i was not getting output after one input.why the thread out was waiting for remaining threads input.
my code is
import java.io.*;
class MyThread extends Thread
BufferedReader bin;
 MyThread()
 super();
 start();
 public void run()
 try
 bin=new BufferedReader(new InputStreamReader(System.in));
 String msg=bin.readLine();
 System.out.println(msg);
 catch(IOException e)
 System.out.println(e);
public class Threads
 public static void main(String args[])
 for(int i=0;i<5;i++)
 new MyThread();
}

Hi Friends
In my program while using thread i found a problem
em in this code .
In this whlie running the 'msg' was printen only
after all 5 inputs are given .
why i was not getting output after one input.why
hy the thread out was waiting for remaining threads
input.Probably because of how the scheduler was rotating among the threads while waiting for input and queueing up output.
When you call readLine, that thread blocks until a line is available. So it probably goes to the next thread's readLine, and so on. All threads are probably blocked waiting for input before you enter a single character.
Something inside the VM has to coordinate the interaction with the console, and between that and your threads, the out stuff just doesn't get a chance to display right away.
In general, you can't predict the order of execution of separate threads.

Thread concurrency problem - how to know when thread is dead?

My applet uses a thread to draw an iteration graph step by step.
The user as the option of pressing two buttons:
- PLAY button - iteration Points are stored in an arrayList and drawn step by step (a sleeping time follows each step) (drawIterations thread)
- TO_END button - iteration Points are all stored in the arrayList (swingworker thread) and after all of them have been stored the graph is drawn instantly.
I have problems in this situation:
When executing the PLAY-button thread, if the user presses TO_END button, the remaining graph lines should draw instantly. Sometimes I get more points on the graph than I should. It seems that the PLAY thread, which I stop when TO_END buton is pressed, still remains storing new points into the arrayList concurrently to the new thread created after TO_END button was pressed .
Any ideas?
I'm already using synchronization.
private volatile Thread drawIterations;
public void playButtonClick(JToggleButton btn) {
 pointSet1 = new ArrayList<Point2D.Double>();
 if (drawIterations == null) drawIterations = new Thread(this, "drawIterations");
 drawIterations.start();
public void toEndButtonClick(JToggleButton btn) {
 stopThread() ;
 pointSet1 = new ArrayList<Point2D.Double>();
 computeIterationGraphPointsAndRefreshGraph();
public synchronized void stopThread() {
 drawIterations = null;
 notify();
private void computeIterationGraphPointsAndRefreshGraphs() {
 SwingWorker worker = new SwingWorker() {
 public Object construct() {
 // compute all iteration points
 //repaint graph
 worker.start();
}Is there a way of testing if a thread is actually dead after setting the thread object to null??

In general, a Thread keeps running until it's run
method completes. Threads don't stop when their
handle is set to null. Your run method should
constantly be checking on a variable to know when to
stop running and exit the run method. In this case,
you could check on the drawIterations variable to see
if it's null. 
 Even using the following line on my run method I get the the same problem:
 
 while (myThread == drawIterations && drawIterations!=null && halfStep < 2 * totalIterations) {
 ...
 
 Here's the whole method:
 (actually there are 2 graphs being drawn and the second is only refreshed every 2 steps:)
 
 public void run() {
 Thread myThread = Thread.currentThread();
 int totalIterations = transientIterations +iterationsToDraw ;
 while (myThread == drawIterations && drawIterations!=null && halfStep < 2 * totalIterations) {
 computeNextHalfIterationGraphPoint( );
 if (!TRANSIENT_IS_ENABLED || halfStep >= 2*transientIterations ) {// is not in transient calculations
 graphArea1.repaint();
 if (halfStep%2 ==0 ) graphArea2.repaint();
 if (halfStep < 2*totalIterations){//no need to execute the following block if at last iteration point
 if (lastIterationPointsFallOutsideGraphArea(toEndCPButtonActive)) break;
 try {
 Thread.sleep(sleepingTimeBetweenHalfIterationRendering);
 if (threadInterrupted ){//if clause included to avoid stepping into a synchronized block if unnecessary
 synchronized (this) {
 while (threadInterrupted && myThread==drawIterations ) wait();
 }
 }
 } catch (InterruptedException e) {
 break;
 }
 }
 }
 stopThread();
 }

Thread scheduling problem in WLS5.1

We use a Timer Servlet to schedule some back end tasks, however we found
          that from time to time the thread scheduling often get delayed or ahead in a
          outragous magtitude.
          We run the servlet inside WLS, and right after start up, the timer works
          perfect, but after long enough time (more than one day), the timer started
          to behave weird. It could get delayed for as much as hours, and then
          suddenly fired up all delayed tasks in a very short period of time. We then
          try to run a very simple Timer doing only wake up every 10 minutes and print
          one line, that failed too. We are running WLS5.1+sp3 on
          Solaris2.6(Generic_105181-19 sun4u sparc SUNW,Ultra-5_10) with jdk1.2.1_04.
          BTW, we found that it ran well on NT, at least for three days without
          problem.
          Any feedback will be appreciated!
          Qingxiang Ke
          below is the source for the simple timer, and deploy properties for it
          inside weblogic.properties file.
          SimpleTimerServlet.java
          package com.cysive.test;
          import java.io.*;
          import java.util.*;
          import javax.servlet.*;
          import javax.servlet.http.*;
          public class SimpleTimerServlet extends HttpServlet
          class Sleepy implements Runnable
          public void run()
          while(true)
          try
          long wakeUpTime = 600 * 1000;
          Thread.currentThread().sleep(wakeUpTime);
          System.out.println(new Date().toString() + " SimpleTimer Yawn
          ............ Yawn ............");
          catch(InterruptedException ie){}
          private static boolean timerIsRunning = false;
          public void init()
          if(! timerIsRunning)
          Thread sleepy = new Thread(new Sleepy());
          sleepy.start();
          timerIsRunning = true;
          public void doGet(HttpServletRequest request,
          HttpServletResponse response)
          throws IOException, ServletException
          doPost(request, response);
          public void doPost(HttpServletRequest request,
          HttpServletResponse response)
          throws IOException, ServletException
          OutputStream os = response.getOutputStream();
          os.write("look at your std out!!!".getBytes());
          os.flush();
          os.close();
          deploy properties in weblogic.properties
          weblogic.httpd.register.simpletimer=com.cysive.test.SimpleTimerServlet
          weblogic.system.startupClass.servletSimpleTimer=weblogic.servlet.utils.Servl
          etStartup
          weblogic.system.startupArgs.servletSimpleTimer=servlet=simpletimer


We use a Timer Servlet to schedule some back end tasks, however we found
          that from time to time the thread scheduling often get delayed or ahead in a
          outragous magtitude.
          We run the servlet inside WLS, and right after start up, the timer works
          perfect, but after long enough time (more than one day), the timer started
          to behave weird. It could get delayed for as much as hours, and then
          suddenly fired up all delayed tasks in a very short period of time. We then
          try to run a very simple Timer doing only wake up every 10 minutes and print
          one line, that failed too. We are running WLS5.1+sp3 on
          Solaris2.6(Generic_105181-19 sun4u sparc SUNW,Ultra-5_10) with jdk1.2.1_04.
          BTW, we found that it ran well on NT, at least for three days without
          problem.
          Any feedback will be appreciated!
          Qingxiang Ke
          below is the source for the simple timer, and deploy properties for it
          inside weblogic.properties file.
          SimpleTimerServlet.java
          package com.cysive.test;
          import java.io.*;
          import java.util.*;
          import javax.servlet.*;
          import javax.servlet.http.*;
          public class SimpleTimerServlet extends HttpServlet
          class Sleepy implements Runnable
          public void run()
          while(true)
          try
          long wakeUpTime = 600 * 1000;
          Thread.currentThread().sleep(wakeUpTime);
          System.out.println(new Date().toString() + " SimpleTimer Yawn
          ............ Yawn ............");
          catch(InterruptedException ie){}
          private static boolean timerIsRunning = false;
          public void init()
          if(! timerIsRunning)
          Thread sleepy = new Thread(new Sleepy());
          sleepy.start();
          timerIsRunning = true;
          public void doGet(HttpServletRequest request,
          HttpServletResponse response)
          throws IOException, ServletException
          doPost(request, response);
          public void doPost(HttpServletRequest request,
          HttpServletResponse response)
          throws IOException, ServletException
          OutputStream os = response.getOutputStream();
          os.write("look at your std out!!!".getBytes());
          os.flush();
          os.close();
          deploy properties in weblogic.properties
          weblogic.httpd.register.simpletimer=com.cysive.test.SimpleTimerServlet
          weblogic.system.startupClass.servletSimpleTimer=weblogic.servlet.utils.Servl
          etStartup
          weblogic.system.startupArgs.servletSimpleTimer=servlet=simpletimer

Thread Pool Problem

Hi,
I amhaving problem with a thread pooling my code once allocates a thread to a user then never is able to find that it is idle. the code is some what like this.
public class foo extends Thread{
pubblic void setPrimeData(Hashtable data){
//sets the primary data
run()
this.isrunning = true;
//does something
this.isrunning= false;
}

You cannot restart a Thread. Once it has run, it cannot be reused. If you want to hand new tasks to threads in a pool, device some means by which you can hand a running (started) thread a new Runnable to execute in its run() method.
Chuck

Weblogic 10 jsp compliation thread block problem

hi
i am using weblogic 10 and jdk1.5.
My application is deployed in ear format, with 2 wars, and 20 ejbs.
The ear works ok with weblogic 8.1.
In the application , one war passes the request to another war, that's the workflow....
Now when the request is passed on the second war, a jsp is supposed to open....but the application get stuck there.
The call is like this in a servlet....
 reqDisp = req.getRequestDispatcher("/newIndex.jsp");
reqDisp.forward(req, res);
The new index jsp is not opened....there is no problem with it it comiples ok....i check with weblogic appc...and it is working on weblogic 8.1.
when i stop the server...the log gives me following exception info.
"ExecuteThread: '12' for queue: 'default'" daemon prio=6 tid=0x2b8edad0 nid=0xc1
0 in Object.wait() [0x2da1e000..0x2da1fb64]
at java.lang.Object.wait(Native Method)
- waiting on <0x07f94608> (a javelin.client.JobWaiter)
at java.lang.Object.wait(Object.java:474)
at javelin.client.JobWaiter.blockUntilFinished(JobWaiter.java:45)
- locked <0x07f94608> (a javelin.client.JobWaiter)
at javelin.client.ClientUtilsImpl.build(ClientUtilsImpl.java:838)
at weblogic.servlet.jsp.JavelinxJSPStub.compilePage(JavelinxJSPStub.java:248)
at weblogic.servlet.jsp.JspStub.prepareServlet(JspStub.java:200)
at weblogic.servlet.jsp.JspStub.prepareServlet(JspStub.java:164)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:235)
- locked <0x07ef8220> (a weblogic.servlet.jsp.JavelinxJSPStub)
at weblogic.servlet.internal.ServletStubImpl.onAddToMapException(ServletStubImpl.java:391)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:309)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:503)
at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:245)
at LCDisplayController.handleProcessing(Unknown Source)
at DisplayControllerServlet.doPost(Unknown Source)
at DisplayControllerServlet.doGet(Unknown Source) at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:226)
at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:124)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:503)
at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:245)
at com.orbitech.workflow.servlet.WFAppListController.openWorkitem(WFAppListController.java:793)
at com.orbitech.workflow.servlet.WFAppListController.processRequest(WFAppListController.java:102)
at com.orbitech.workflow.servlet.WFAppController.doProcessRequest(WFAppController.java:97)
at com.orbitech.workflow.servlet.WFAppController.doGet(WFAppController.java:64) at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
i think the there is thread blocking and the jsp is not getting compiled or smthing....
i am unable to understnd the exception....
any help, suggestion ? thanks in advance.

We are using jBPM and Hibernate in our application which runs fine on other java application servers. On Weblogic we were getting an error:
org.hibernate.HibernateException: Errors in named queries: GraphSession...........
By adding:
<container-descriptor>
<prefer-web-inf-classes>true</prefer-web-inf-classes>
</container-descriptor>
to our weblogic.xml, Weblogic used our Hibernate3 and antl-2.7.6 .jar files which resolved this issue but created multiple CompilationException errors in many .jsp's. (as follows)
Error 500--Internal Server Error
weblogic.servlet.jsp.CompilationException: Failed to compile JSP /WEB-INF/jsp/struts/dashboards/portfolio_chart.jsp
portfolio_chart.jsp:1:1: The validator class: "org.apache.taglibs.standard.tlv.JstlCoreTLV" has failed with the following exception: "java.lang.ClassCastException: weblogic.xml.jaxp.RegistrySAXParserFactory".
<%@ taglib uri="/jstl-core" prefix="c" %>
^---------------------------------------^
portfolio_chart.jsp:1:1: The validator class: "com.primavera.pvweb.taglib.JSMessageTagLibraryValidator" has failed with the following exception: "java.lang.ClassCastException: weblogic.xml.jaxp.RegistrySAXParserFactory".
<%@ taglib uri="/jstl-core" prefix="c" %>
^---------------------------------------^
 at weblogic.servlet.jsp.JavelinxJSPStub.compilePage(JavelinxJSPStub.java:298)
 at weblogic.servlet.jsp.JspStub.prepareServlet(JspStub.java:216)
 at weblogic.servlet.jsp.JspStub.prepareServlet(JspStub.java:165)
 at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:235)
 at weblogic.servlet.internal.ServletStubImpl.onAddToMapException(ServletStubImpl.java:394)
 at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:309)
Is this a Weblogic bug ?

Thread suspension problem

I have a swing problem, which needs some threading code, but I barely understand it.
My text field components change the underlying data when the focus is lost. When I click on a different tab in the JTabbedPane while editing a field, at the time the ChangeListener runs, the focus is not lost, so data for the input field is not updated. I tried the following to wait for one of the new tab pane components to be shown, but it does not work.
class TabFocusListener implements ComponentListener
     private Component comp;
     public TabFocusListener(Component comp)
          this.comp = comp;
          comp.addComponentListener(this);
          try
               // prg. gets the lock for this object and waits until comp. shown
               synchronized(this) { wait(10000); }
          catch(InterruptedException ex)
     public void componentShown(ComponentEvent e)
          comp.removeComponentListener(this);
          // frees prg. thread that holds the lock for this object
          notifyAll();
     public void componentHidden(ComponentEvent e){}
     public void componentMoved(ComponentEvent e){}
     public void componentResized(ComponentEvent e){}
}

There's a Swing forum for Swing problems. Those guys probably have a solution since they do Swing all day.
You're waiting/notifying on different objects. "this" refers to the current object. If two different thread call the constructor then there will be two different objects ("this").
It's also a very bad idea to put a wait inside a constructor. See Brian Goetz's article here: http://www-128.ibm.com/developerworks/java/library/j-jtp0618.html
You cannot use the object until it is fully constructed.

Thread Concurrency problem

Hello
i have an application where i have about 6 threads....I have each of this thread working independently ..i.e each thread has its publis static main method.....they are continuously running..... and they are working correctly.... but the problem is that i have run each thread explicitly....
But now i want to combine all these threads into one thread so that when i run my java application all these threads will start running.....I tried doing it but the problem is that the first thread itself runs...the other threads do not run...... how do i do this????
The code of the program where i clubbed the threads is
public class MainThread
public static void main(String arg[])
NewThread n= new NewThread() ;
System.out.println("in psvm") ;
class NewThread extends Thread
String name; // name of thread
Thread t;
NewThread()
System.out.println("in newthread") ;
SMSSendThread sms=new SMSSendThread() ;
UsernameThread user=new UsernameThread() ;
user.start() ;
SendInbox inbox=new SendInbox() ;
inbox.start() ;
DeleteSMS delete=new DeleteSMS() ;
delete.start();
My start method of each of these thread contains ie.deleteSMS,SendInbox
public void start()
HashSet<Socket> clients = new HashSet<Socket>() ;
try
Boolean listening=true ;
ServerSocket ss=new ServerSocket(2345) ;
Socket socket=new Socket() ;
int id=0;
while(listening)
System.out.println("Detecting Client please Wait in send thread:=") ;
socket = ss.accept();
clients.add(socket);
System.out.println("clients display:="+clients) ;
if(clients.contains(socket))
InetAddress clientIP=socket.getInetAddress() ;
System.out.println("the ip addrss of the client:="+clientIP) ;
new ConnectionHandlerdelete(socket).start() ;
The problem is that only the Username thread exceutes priopely the other two are not running!!!!

Then why are the other threads not runningIf that is your code you are mistaken about this.
> the newthread class runs as it is supposed to
The newthread class constructor runs as it is supposed to , and it starts the other threads. You never call start on it so it never executes its run() method. It doesn't even appear to have a run() method.
So either this is not your real code or your observations are mistaken.

Thread conceptual problem

Similar Messages

Maybe you are looking for