Servlet Thread Pools for iPlanet WS 4.1

We have iPlanet WS 4.1 SP 5, running on HP UX. Wanted to make sure servlets run fast, so set up servlet thread pool. Initial result was that even the startup servlet could not be loaded, got stack overflow. Reduced number of threads from 60 to 5. Now startup servlet kicked off OK, but a subsequent servlet processing a request bombed with same error. This is obviously some kind of resource issue; how does one allocate enough memory or whatever it needs to handle the thread pool? Do I really even need a thread pool?

Thanks, and a follow-up question: at that reference, it seemed to imply there is really no need to allocate a user thread pool if running on Unix. Could even slow down the application. Am I likely to be OK with about 300 concurrent users if I don't allocate a thread pool? I was afraid they'd be single-threaded through the front controller servlet if I did not specifically allocate and use a thread pool, but perhaps multiple threads are already built into the container?

Similar Messages

Servlet thread pool

Is there any way I can create my own init() for the threads in the servlet thread pool (by overriding some method or through other means)? (Not to be confused with the servlet's init().)

web server itself is a thread pool implementation, unlesss your thread has other purpose, if not it is suited and enough for you do not implement another thread for it. If you want some init method, you can call from other class before start of your thread pooling.
Hopefully can help you...

Thread pools for execute queues

We've set up thread pools for several execute queues dedicated to high-load servlets
in our application. Once in a while, we get into a condition in which none of
these threads are available and then the threads never become available - we have
to restart the server.
I realize that this is a pretty generic description of the problem :-) but I wonder
if anyone else has encountered this and has an idea what might be causing it ?
Right now I am guessing that something in our code causes a resource contention
that eventually deadlocks all the threads. But that is just a guess.

Ethan,
"Ethan Allen" <[email protected]> wrote in message
news:3e0220a1$[email protected]..
Thanks, Dimitri and Slava !
I will do this and learn a little emore ...FYI, there is a web site dedicated to weblogic documentation -
http://e-docs.bea.com/
Pick your server version, go to "Search", type "thread dump".
Regards,
Slava Imeshev
>
ethan
"Slava Imeshev" <[email protected]> wrote:
Hi Ethan,
For windows press <Ctrl>+<Break> in the server shell window,
for *nix send kill -3 {server PID}.
Regards,
Slava Imeshev
"Ethan Allen" <[email protected]> wrote in message
news:3e020fb4$[email protected]..
Thanks for your reply, Dimitri.
We have not looked at thread dumps. How may we do this ?
Ethan
"Dimitri I. Rakitine" <[email protected]> wrote:
Did you try looking at thread dumps when this happens ?
Ethan Allen <[email protected]> wrote:
We've set up thread pools for several execute queues dedicated to
high-load
servlets
in our application. Once in a while, we get into a condition in
which
none of
these threads are available and then the threads never become
available
- we have
to restart the server.
I realize that this is a pretty generic description of the problem:-) but I wonder
if anyone else has encountered this and has an idea what might be
causing
it ?
Right now I am guessing that something in our code causes a
resource
contention
that eventually deadlocks all the threads. But that is just a
guess.
>>>>
Dimitri

Custom thread pool for Java 8 parallel stream

It seems that it is not possible to specify thread pool for Java 8 parallel stream. If that's so, the whole functionality is useless in most of the situations. The only situation I can safely use it is a small single threaded application written by one person.
In all other cases, if I can not specify the thread pool, I have to share the default pool with other parts of the application. If someone submits a task that takes a lot of time, my tasks will get stuck. Is that correct or am I overlooking something?
Imagine that someone submits slow networking operation to the fork-join pool. It's not a good idea, but it's so tempting that it will be happening. In such case, all CPU intensive tasks executed on parallel streams will wait for the networking task to finish. There is nothing you can do to defend your part of the application against such situations. Is that so?

You are absolutely correct. That isn't the only problem with using the F/J framework as the parallel engine for bulk operations. Have a look http://coopsoft.com/ar/Calamity2Article.html

Configuration of Thread Pool for CQ's Web Container

I am trying to detrmine whether there is any specific configuration for tuning the web container thread pool for CQ. The only configuration I observe is OSGi 's Apache Sling Event Thread Pool but tuning this does not directly correlate to the thread pool that is used for serving web requests by the publish instance.
Any help would be greatly appreciated as I work through tuning our CQ instance.

Unfortunately, the max thread settings is not exposed in CQ 5.5.However, all the other configurable settings (equivalent for server.xml) can be seen at [1]
[1] http://localhost:4502/system/console/configMgr/org.apache.felix.http
This is fixed in CQ 5.6 current release.
Thanks,
Varun

[svn] 1605: Bug: BLZ-155 - Deadlock using a thread pool for tomcat connectors

Revision: 1605
Author: [email protected]
Date: 2008-05-07 14:24:53 -0700 (Wed, 07 May 2008)
Log Message:
Bug: BLZ-155 - Deadlock using a thread pool for tomcat connectors
QA: Yes - Jorge verified in the QE lab
Doc: No
Ticket Links:
http://bugs.adobe.com/jira/browse/BLZ-155
Modified Paths:
blazeds/branches/3.0.x/modules/core/src/java/flex/messaging/client/EndpointPushNotifier.j ava

Cross post: http://forum.java.sun.com/thread.jspa?threadID=5215686&tstart=0
If you must post across forums, just post in the most relevant one and then give the link to that in the other posts.

Thread pool for Servlets

          Hi all,
          I am facing a big problem while doing a concurrent testing of my web application.
          I am testing with 60 concurrent users.
          I have set the database connection pool minimum capacity to 50, capacity increment
          to 10 and maximum capacity to 100.
          While there is no problem in getting database connection, the session variables
          are getting mixed up (i.e. the session variable for one user is coming up as that
          for another user!!!).
          Does it have something to do with configuring some pool for servlets threads or
          something?
          Please help.
          Thanks a lot in advance and best regards,
          Jaya


          Hi all,
          I am facing a big problem while doing a concurrent testing of my web application.
          I am testing with 60 concurrent users.
          I have set the database connection pool minimum capacity to 50, capacity increment
          to 10 and maximum capacity to 100.
          While there is no problem in getting database connection, the session variables
          are getting mixed up (i.e. the session variable for one user is coming up as that
          for another user!!!).
          Does it have something to do with configuring some pool for servlets threads or
          something?
          Please help.
          Thanks a lot in advance and best regards,
          Jaya

Restricting Thread Pool for Servlet instances

I am using WebLogic5.1.0 version wherein I am registering a Servlet which
would be called by all the clients connecting
to my aplication. The servlet's service methods is taking some time to
execute. Since the servlet is following a SingleThreadModel, when there are
a large number of Clients connected, the number instances of Servlets
created are very high and the number of thread in the Application Server
process becomes very high affecting the performance of the other
applications.
Is it possible to restrict the number of instances of the servlets that get
created in the Application server ?
What are the setting required to achieve this ?
Sandeep

Hi.
I'm not aware of a property setting that allows you to restrict the number of
servlet instances in WLS for the SingleThreadModel. The number of execute
threads is fixed - it does not grow depending on load. You can set this value
in the weblogic.properties file by setting weblogic.system.executeThreadCount.
This value is 15 by default.
It does sound like you are reaching the max capability of your
server/hardware. You should try tuning WLS.
Here are a couple of suggestions:
1. Try adjusting the executeThreadCount value to a higher value. Start by
setting it to 30 - see if that makes any difference.
2. Check out the following tuning guide:
http://www.weblogic.com/docs51/admindocs/tuning.html
3. Here is a list of admin properties that might aid in tuning:
http://www.weblogic.com/docs51/adminhelp/AdminPropertyHelp.html
4. If you are still having problems you might do better by posting this issue
to the performance newsgroup.
Regards,
Michael
Sandeep Rajpathak wrote:
I am using WebLogic5.1.0 version wherein I am registering a Servlet which
would be called by all the clients connecting
to my aplication. The servlet's service methods is taking some time to
execute. Since the servlet is following a SingleThreadModel, when there are
a large number of Clients connected, the number instances of Servlets
created are very high and the number of thread in the Application Server
process becomes very high affecting the performance of the other
applications.
Is it possible to restrict the number of instances of the servlets that get
created in the Application server ?
What are the setting required to achieve this ?
Sandeep--
Michael Young
Developer Relations Engineer
BEA Support

Thread pool configuration for write-behind cache store operation?

Hi,
Does Coherence have a thread pool configuration for the Coherence CacheStore operation?
Or the CacheStore implementation needs to do that?
We're using write-behind and want to use multiple threads to speed up the store operation (storeAll()...)
Thanks in advance for your help.

user621063 wrote:
Hi,
Does Coherence have a thread pool configuration for the Coherence CacheStore operation?
Or the CacheStore implementation needs to do that?
We're using write-behind and want to use multiple threads to speed up the store operation (storeAll()...)
Thanks in advance for your help.Hi,
read/write-through operations are carried out on the worker thread (so if you configured a thread-pool for the service the same thread-pool will be used for the cache-store operation).
for write-behind/read-ahead operations, there is a single dedicated thread per cache above whatever thread-pool is configured, except for remove operations which are synchronous and still carried out on the worker thread (see above).
All above is of course per storage node.
Best regards,
Robert

Cold Fusion in a generic thread pool and enabling JAVA don't mix

I've got Cold Fusion MX installed on a server running Sun One 6.1. I ran into a problem trying to enable JAVA (for servlet support) which I had previous disabled because I didn't use it.
Well, when I went to enable JAVA on the server last week, the service wouldn't restart and the error logs gave me no indication of the problem.
Through a tedious trial-and-error process I've found that having Cold Fusion running under a generic thread pool while trying to have JAVA (the j2ee plugin) running under Sun One simply doesn't work (for whatever reason).
Once I killed the pool, everything runs fine.
Does anyone happen to know why this is? I keep CFMX under its own thread pool because there are certain elements to CFMX that aren't wholly stable and can result in CFMX crashing. If it crashes, the process keeps accepting requests, but never processes them. I'd like to keep the native thread pool free to keep accepting non-CFMX requests even when CFMX crashes.
Thus the separate thread pool for CFMX.
But now I can't run CFMX in a separate thread pool with JAVA enabled.
Anyone have any insights into why this is?
Thanks

Two things. Firstly, it's better to use private static final Object classLock = new Object();because that saves you worrying about whether any other code synchronises on it. Secondly, if you do decide to go for the delegation route then java.lang.reflect.Proxy may be a good way forward.

The different thread pools in 6.1

Boy am I just flooded with just 6.1 migration issues. Life was much
simpler with weblogic.properties file.
Looking at Config.Dtd I couldnt see the different thread pools that WLS
5.1 offered.
How do I do set up thread pools for
a) Servlets
b) RMI
c) JMS
In 5.1 you had a servletthreadpool, an executethreadcount(for RMI) and a
jms thread pool.

In 6.1
There isn't any seperate execute ThreadPool for servlets.
The only thread pool that you can tune is the default
queue which can be done via console. Ofcourse you can
configure user defined thread queues.
Also there are some internal thread pools that are not
exposed to the developers. for e.g. admin queue, replication
queue , console queue , rmi queue , jms queue etc....
If you still want to route your servlet requests via a
seperate thread queue, you have to specify
the dispatch policy & the queue name.
see below
http://e-docs.bea.com/wls/docs61/perform/AppTuning.html#1105201
Kumar
Aswin Dinakar wrote:
Boy am I just flooded with just 6.1 migration issues. Life was much
simpler with weblogic.properties file.
Looking at Config.Dtd I couldnt see the different thread pools that WLS
5.1 offered.
How do I do set up thread pools for
a) Servlets
b) RMI
c) JMS
In 5.1 you had a servletthreadpool, an executethreadcount(for RMI) and a
jms thread pool.

CORBA thread pools

Is there a code sample that takes a CORBA request and passes it to an available
thread in a thread pool. All the multi-threaded examples I have seen seem to rely
on creating a thread on receipt of a request/creation of an object, which could
be quite inefficient.
-Giles Cory

Ethan,
"Ethan Allen" <[email protected]> wrote in message
news:3e0220a1$[email protected]..
Thanks, Dimitri and Slava !
I will do this and learn a little emore ...FYI, there is a web site dedicated to weblogic documentation -
http://e-docs.bea.com/
Pick your server version, go to "Search", type "thread dump".
Regards,
Slava Imeshev
>
ethan
"Slava Imeshev" <[email protected]> wrote:
Hi Ethan,
For windows press <Ctrl>+<Break> in the server shell window,
for *nix send kill -3 {server PID}.
Regards,
Slava Imeshev
"Ethan Allen" <[email protected]> wrote in message
news:3e020fb4$[email protected]..
Thanks for your reply, Dimitri.
We have not looked at thread dumps. How may we do this ?
Ethan
"Dimitri I. Rakitine" <[email protected]> wrote:
Did you try looking at thread dumps when this happens ?
Ethan Allen <[email protected]> wrote:
We've set up thread pools for several execute queues dedicated to
high-load
servlets
in our application. Once in a while, we get into a condition in
which
none of
these threads are available and then the threads never become
available
- we have
to restart the server.
I realize that this is a pretty generic description of the problem:-) but I wonder
if anyone else has encountered this and has an idea what might be
causing
it ?
Right now I am guessing that something in our code causes a
resource
contention
that eventually deadlocks all the threads. But that is just a
guess.
>>>>
Dimitri

The problem in the thread pool implemented by myself

Hello, I need to a thread pool in J2ME CDC 1.0 + FP 1.0, so I implemented a simple one by myself that also meets my own requirement.
Here is the main idea:
The thread pool creates a fixed number of threads in advance. When a task comes, it is put in the waiting list. All threads tries to get the tasks from the waiting list. If no task exists, the threads wait until someone wakes them up.
Here are the requirements from myself:
1. when a task has finished its work in one execution, it is put in the waiting list for the next run.
2. the task can control the delay between when the task owner tries to put it in the waiting list and when the task is actually put in the waiting list. I need this function because sometimes I don't want the tasks to run too often and want to save some CPU usage.
In my program, I creates two thread pools. In one pool, every task don't use the delay, and the thread pool works very well. The other pool has the tasks that use the delay, and sometimes, as I can see from the printed information, there are many tasks in the waiting list but 0 or 1 thread executes tasks. It seems that the waiting threads cannot wake up when new tasks comes.
I suspect the code in addTask(), but cannot find the reason why it fails. Could anyone please help me find out the bug in my code? I put the code of thread pool below
Thank you in advance
Zheng Da
ThreadPool.java
package j2me.concurrent;
import java.util.LinkedList;
import java.util.Timer;
import java.util.TimerTask;
import alvis.general.Util;
public class ThreadPool {
     private int maxQueueSize;
     private boolean running = true;
     private Thread[] threads;
     private LinkedList tasks = new LinkedList();
     private Timer timer = new Timer(true);
     private AtomicInteger usingThreads = new AtomicInteger(0);
     private synchronized boolean isRunning() {
          return running;
     private synchronized void stopRunning() {
          running = false;
     private synchronized PoolTask getTask() {
          while (tasks.isEmpty() && isRunning()) {
               try {
                    this.wait();
               } catch (InterruptedException e) {
                    e.printStackTrace();
          if (tasks.isEmpty())
               return null;
          // Util.log.info(Thread.currentThread().getName() +
          // " gets a task, left tasks: " + tasks.size());
          return (PoolTask) tasks.removeFirst();
     private synchronized void addTaskNoDelay(PoolTask task) {
          tasks.addLast(task);
          notifyAll();
     private synchronized void addTask(final PoolTask task) {
          long delay = task.delay();
          if (delay == 0) {
               addTaskNoDelay(task);
          } else {
               timer.schedule(new TimerTask() {
                    public void run() {
                         addTaskNoDelay(task);
               }, delay);
     private synchronized int numTasks() {
          return tasks.size();
     private class PoolThread extends Thread {
          public void run() {
               Util.poolThreads.inc();
               while (isRunning()) {
                    PoolTask task = getTask();
                    if (task == null) {
                         Util.poolThreads.dec();
                         return;
                    usingThreads.inc();
                    long currentTime = System.currentTimeMillis();
                    task.run();
                    long elapsedTime = System.currentTimeMillis() - currentTime;
                    if (elapsedTime > 100)
                         System.err.println(task.toString() + " takes " + ((double) elapsedTime)/1000 + "s");
                    usingThreads.dec();
                    if (!task.finish()) {
                         addTask(task);
               Util.poolThreads.dec();
     public ThreadPool(int size, int taskQueueSize) {
          maxQueueSize = taskQueueSize;
          threads = new Thread[size];
          for (int i = 0; i < threads.length; i++) {
               threads[i] = new PoolThread();
               threads.start();
     public synchronized boolean executor(PoolTask task) {
          if (!isRunning()) {
               return false;
          Util.log.info("Thread Pool gets " + task + ", there are "
                    + numTasks() + " waiting tasks");
          if (numTasks() >= maxQueueSize) {
               return false;
          addTask(task);
          return true;
     public synchronized void destroy() {
          stopRunning();
          timer.cancel();
          // TODO: I am not sure it can wake up all threads and destroy them.
          this.notifyAll();
     public synchronized void printSnapshot() {
          System.err.println("using threads: " + usingThreads + ", remaining tasks: " + tasks.size());
PoolTask.javapackage j2me.concurrent;
public interface PoolTask extends Runnable {
     * It shows if the task has already finished.
     * If it isn't, the task will be put in the thread pool for the next execution.
     * @return
     boolean finish();
     * It shows the delay in milliseconds that the task is put in the thread pool.
     * @return
     long delay();

are receiving/sends tasks packets time consuming operation in your case or not? if it is not you do not need to use thread pools at all. you can create a queue like in your code through the linked list and dispatch this queue periodically with minimum monitor usage. try this.
import java.util.LinkedList;
public class PacketDispatcher extends Thread {
    LinkedList list = new LinkedList();
    public PacketDispatcher (String name) {
        super(name);
    public void putTask(Task task) {
        synchronized (list) {
            list
                    .add(task);
            list.notify();
    public void run() {
        while (true/* your condition */) {
            Task task = null;
            synchronized (list) {
                while (list.isEmpty())
                    try {
                        list.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                task = (Task)list
                        .poll();
            if (task == null) {
                try {
                    Thread
                            .sleep(1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                continue;
            task
                    .run();
            if (!task.isFinished()) {
                putTask(task);
            Thread
                    .yield();
    public static void main(String[] args) {
        // just for test
        try {
            Thread.sleep (10000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        PacketDispatcher dispatcher = new PacketDispatcher("Packet Dispatcher");
        Task task = new Task();
        dispatcher.putTask(task);
        dispatcher.start();
        try {
            Thread.sleep (10000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        Task task2 = new Task();
        dispatcher.putTask(task2);
class Task {
    long result = 0;
    public boolean isFinished () {
        if (getResult() >= 10000000) {
            return true;
        return false;
    public void run() {
        for (int i = 0; i < 1000; i++) {
            result += i;
    public long getResult () {
        return result;
}

Fixed Size Thread Pool which infinitely serve task submitted to it

Hi,
I want to create a fixed size thread pool say of size 100 and i will submit around 200 task to it.
Now i want it to serve them infinitely i.e once all tasks are completed re-do them again and again.
public void start(Vector<String> addresses)
      //Create a Runnable object of each address in "addresses"
       Vector<FindAgentRunnable> runnables = new Vector<FindAgentRunnable>(1,1);
        for (String address : addresses)
            runnables.addElement(new FindAgentRunnable(address));
       //Create a thread pool of size 100
        ExecutorService pool = Executors.newFixedThreadPool(100);
        //Here i added all the runnables to the thread pool
         for(FindAgentRunnable runnable : runnables)
                pool.submit(runnable);
            pool.shutdown();
}Now i wants that this thread pool execute the task infinitely i.e once all the tasks are done then restart all the tasks again.
I have also tried to add then again and again but it throws a java.util.concurrent.RejectedExecutionException
public void start(Vector<String> addresses)
      //Create a Runnable object of each address in "addresses"
       Vector<FindAgentRunnable> runnables = new Vector<FindAgentRunnable>(1,1);
        for (String address : addresses)
            runnables.addElement(new FindAgentRunnable(address));
       //Create a thread pool of size 100
        ExecutorService pool = Executors.newFixedThreadPool(100);
        for(;;)
            for(FindAgentRunnable runnable : runnables)
                pool.submit(runnable);
            pool.shutdown();
            try
                pool.awaitTermination(Long.MAX_VALUE, TimeUnit.SECONDS);
            catch (InterruptedException ex)
                Logger.getLogger(AgentFinder.class.getName()).log(Level.SEVERE, null, ex);
}Can anybody help me to solve this problem?
Thnx in advance.

Ravi_Gupta wrote:
*@ kajbj*
so what should i do?
can you suggest me a solution?Consider this thread "closed". Continue to post in your other thread. I, and all others don't want to give answers that already have been given.

Combining the fixed and cached thread pools

Is there a way to 'combine' the behavior of cached and fixed thread pools ? I have a requirement where
- at startup, I need to execute a fixed number of short-lived tasks at the background
- after startup, on demand, I need to run one short-lived task at a time
If I use a fixed thread pool for my startup processing, it creates the fixed number of threads to process the tasks. But subsequently, those many threads are not required since my task submission is going to be one at a time. The remaining (n-1) threads therefore are really sitting idle & useless.
If I use a cached thread pool, then I cannot constrain the number of threads to run at startup (since it creates one for each task). Though it ends up taking those threads out after they are idle for a fixed period. But I'm worried that it might create many threads and possibly slowing down the startup ?
Is there a way to create a pool with a fixed number of threads but 'remove' a set of threads when they are idle ?
TIA

v_bala wrote:
Thanks. The SynchronousQueue worked as expected. But I tried a LinkedBlockingQueue with size 1 hoping that would cause the second task submission to cause a new thread creation. It didn't. Instead it queues up the request (maybe the doc in ThreadPoolExecutor says that when it mentions "If corePoolSize or more threads are running, the Executor always prefers queuing a request rather than adding a new thread"). I suppose if I were to try another it would create another thread ? (I was testing with only two tasks - the first one ended up creating a thread for the task and the next got queued since the queue capacity is 1)yes, the TPE will not start adding threads until the queue starts rejecting them. kind of odd in my opinion, but that's how it works.
Btw, that was an interesting idea to add a task that scale the core pool number down ! Currently it comes back down to just the one thread (my core pool size is one) after the idle timeout but your idea may give me a slightly better response since it will scale down the core pool size quicker....I suppose if there was a task submission before that idle time there maybe a performance hit (but I don't anticipate that in my case )?actually, that won't scale things down any faster. changing the core pool size will not ditch the other threads immediately, they will still stick around until they idle timeout. changing the core pool size allows you to not worry about the queue implementation (the first solution). you can set the initial core pool size to your "max" size on startup, then drop it down for the normal processing, all the while using a linkedblockingqueue of unlimited size.

Servlet Thread Pools for iPlanet WS 4.1

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