can any one help me to understand the below thread blocks in netty4.0.15
nioEventLoopGroup-5-13 [BLOCKED] CPU time: 38s
sun.nio.ch.SelectorImpl.select(long)
io.netty.channel.nio.NioEventLoop.select()
io.netty.channel.nio.NioEventLoop.run()
io.netty.util.concurrent.SingleThreadEventExecutor$2.run()
java.lang.Thread.run()
nioEventLoopGroup-5-2 [BLOCKED] CPU time: 40s
java.lang.Class.isAnnotationPresent(Class)
io.netty.channel.ChannelHandlerAdapter.isSharable()
io.netty.channel.DefaultChannelPipeline.checkMultiplicity(ChannelHandlerContext)
io.netty.channel.DefaultChannelPipeline.addLast0(String, DefaultChannelHandlerContext)
io.netty.channel.DefaultChannelPipeline.addLast(EventExecutorGroup, String, ChannelHandler)
io.netty.channel.DefaultChannelPipeline.addLast(String, ChannelHandler)
org.zestadz.adsearch.server.impl.KomliAdServerInitializer.initChannel(SocketChannel)
org.zestadz.adsearch.server.impl.KomliAdServerInitializer.initChannel(Channel)
io.netty.channel.ChannelInitializer.channelRegistered(ChannelHandlerContext)
io.netty.channel.DefaultChannelHandlerContext.invokeChannelRegistered()
io.netty.channel.DefaultChannelHandlerContext.fireChannelRegistered()
io.netty.channel.DefaultChannelPipeline.fireChannelRegistered()
io.netty.channel.AbstractChannel$AbstractUnsafe.register0(ChannelPromise)
io.netty.channel.AbstractChannel$AbstractUnsafe.access$100(AbstractChannel$AbstractUnsafe, ChannelPromise)
io.netty.channel.AbstractChannel$AbstractUnsafe$1.run()
io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(long)
io.netty.channel.nio.NioEventLoop.run()
io.netty.util.concurrent.SingleThreadEventExecutor$2.run()
java.lang.Thread.run()
blocked threads i took it from yourkit profiler
This is normal for a worker to block on select() waiting for incoming messages
Related
I have a play scala application running on play 2.7. this is used as a middleware for our frontend and it has rest end points.
Now I am running two different instances on cloud and using nginx and bound these two servers and load balance it with round robin.
Now I am having a problem that the servers goes down quite often i.e. 3 times a day and interesting thing is both server goes down at same time. When I looked at it says out of memory exception on the both servers. I tried to print javaheapdump for out of memory but getting no dump . I am still analysing the thread dump to figure out what might be the actual cause of my server going down but what pins me is why the two servers are going down at the same time.
Out of thread dump I see there are 7707 thread with sleeping state. here it is
"Connection evictor" #146 daemon prio=5 os_prio=0 cpu=2.33ms elapsed=1822.02s tid=0x00007f8a840c4800 nid=0x194 waiting on condition [0x00007f8a58a5e000]
java.lang.Thread.State: TIMED_WAITING (sleeping)
at java.lang.Thread.sleep(java.base#11/Native Method)
at org.apache.http.impl.client.IdleConnectionEvictor$1.run(IdleConnectionEvictor.java:66)
at java.lang.Thread.run(java.base#11/Thread.java:834)
This what I see when server goes down
[35966.967s][warning][os,thread] Failed to start thread - pthread_create failed (EAGAIN) for attributes: stacksize: 1024k, guardsize: 0k, detached.
Uncaught error from thread [application-akka.actor.default-dispatcher-1398Uncaught error from thread [application-akka.actor.default-dispatcher-1395]: ]: unable to create native thread: possibly out of memory or process/resource limits reachedunable to create native thread: possibly out of memory or process/resource limits reached, shutting down JVM since 'akka.jvm-exit-on-fatal-error' is enabled for, shutting down JVM since 'akka.jvm-exit-on-fatal-error' is enabled for ActorSystem[ ActorSystem[applicationapplication]
]
java.lang.OutOfMemoryError: unable to create native thread: possibly out of memory or process/resource limits reached
at java.base/java.lang.Thread.start0(Native Method)
at java.base/java.lang.Thread.start(Thread.java:803)
at org.apache.http.impl.client.IdleConnectionEvictor.start(IdleConnectionEvictor.java:96)
at org.apache.http.impl.client.HttpClientBuilder.build(HttpClientBuilder.java:1219)
at org.apache.solr.client.solrj.impl.HttpClientUtil.createClient(HttpClientUtil.java:287)
at org.apache.solr.client.solrj.impl.HttpClientUtil.createClient(HttpClientUtil.java:298)
at org.apache.solr.client.solrj.impl.HttpClientUtil.createClient(HttpClientUtil.java:236)
at org.apache.solr.client.solrj.impl.HttpClientUtil.createClient(HttpClientUtil.java:223)
at org.apache.solr.client.solrj.impl.HttpSolrClient.<init>(HttpSolrClient.java:198)
at org.apache.solr.client.solrj.impl.HttpSolrClient$Builder.build(HttpSolrClient.java:934)
at com.github.takezoe.solr.scala.SolrClient$.$anonfun$$lessinit$greater$default$2$1(SolrClient.scala:11)
at com.github.takezoe.solr.scala.SolrClient.<init>(SolrClient.scala:14)
at service.tvt.solr.SolrPolygonService.getSuburbBoundary(SolrPolygonService.scala:212)
at service.tvt.search.OrbigoSearchService.mapfeeder(OrbigoSearchService.scala:54)
at service.bto.business_categories.MeedssCountService.$anonfun$suburbMeedssCount$2(MeedssCountService.scala:81)
at scala.collection.immutable.List.map(List.scala:287)
at service.bto.business_categories.MeedssCountService.suburbMeedssCount(MeedssCountService.scala:80)
at controllers.bto.industry_categories.meedss.MeedssController.$anonfun$suburbMeedssCount$1(MeedssController.scala:38)
at play.api.mvc.ActionBuilder.$anonfun$apply$11(Action.scala:368)
at scala.Function1.$anonfun$andThen$1(Function1.scala:52)
at play.api.mvc.ActionBuilderImpl.invokeBlock(Action.scala:489)
at play.api.mvc.ActionBuilderImpl.invokeBlock(Action.scala:487)
at play.api.mvc.ActionBuilder$$anon$9.invokeBlock(Action.scala:336)
at play.api.mvc.ActionBuilder$$anon$9.invokeBlock(Action.scala:331)
at play.api.mvc.ActionBuilder$$anon$10.apply(Action.scala:426)
at play.api.mvc.Action.$anonfun$apply$2(Action.scala:98)
at play.api.libs.streams.StrictAccumulator.$anonfun$mapFuture$4(Accumulator.scala:184)
at scala.util.Try$.apply(Try.scala:209)
at play.api.libs.streams.StrictAccumulator.$anonfun$mapFuture$3(Accumulator.scala:184)
at akka.stream.impl.Transform.apply(TraversalBuilder.scala:159)
at akka.stream.impl.PhasedFusingActorMaterializer.materialize(PhasedFusingActorMaterializer.scala:515)
at akka.stream.impl.PhasedFusingActorMaterializer.materialize(PhasedFusingActorMaterializer.scala:450)
at akka.stream.impl.PhasedFusingActorMaterializer.materialize(PhasedFusingActorMaterializer.scala:443)
at akka.stream.scaladsl.RunnableGraph.run(Flow.scala:629)
at play.api.libs.streams.Accumulator$.$anonfun$futureToSink$2(Accumulator.scala:262)
at scala.concurrent.Future.$anonfun$flatMap$1(Future.scala:303)
at scala.concurrent.impl.Promise.$anonfun$transformWith$1(Promise.scala:37)
at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:60)
at play.api.libs.streams.Execution$trampoline$.execute(Execution.scala:72)
at scala.concurrent.impl.CallbackRunnable.executeWithValue(Promise.scala:68)
at scala.concurrent.impl.Promise$DefaultPromise.dispatchOrAddCallback(Promise.scala:312)
at scala.concurrent.impl.Promise$DefaultPromise.onComplete(Promise.scala:303)
at scala.concurrent.impl.Promise.transformWith(Promise.scala:36)
at scala.concurrent.impl.Promise.transformWith$(Promise.scala:34)
at scala.concurrent.impl.Promise$DefaultPromise.transformWith(Promise.scala:183)
at scala.concurrent.Future.flatMap(Future.scala:302)
at scala.concurrent.Future.flatMap$(Future.scala:302)
at scala.concurrent.impl.Promise$DefaultPromise.flatMap(Promise.scala:183)
at play.api.libs.streams.Accumulator$.$anonfun$futureToSink$1(Accumulator.scala:261)
at akka.stream.impl.Transform.apply(TraversalBuilder.scala:159)
at akka.stream.impl.PhasedFusingActorMaterializer.materialize(PhasedFusingActorMaterializer.scala:515)
at akka.stream.impl.PhasedFusingActorMaterializer.materialize(PhasedFusingActorMaterializer.scala:450)
at akka.stream.impl.PhasedFusingActorMaterializer.materialize(PhasedFusingActorMaterializer.scala:443)
at akka.stream.scaladsl.RunnableGraph.run(Flow.scala:629)
at play.api.libs.streams.SinkAccumulator.run(Accumulator.scala:144)
at play.api.libs.streams.SinkAccumulator.run(Accumulator.scala:148)
at play.core.server.AkkaHttpServer.$anonfun$runAction$4(AkkaHttpServer.scala:441)
at akka.http.scaladsl.util.FastFuture$.strictTransform$1(FastFuture.scala:41)
at akka.http.scaladsl.util.FastFuture$.$anonfun$transformWith$3(FastFuture.scala:51)
at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:60)
at akka.dispatch.BatchingExecutor$AbstractBatch.processBatch(BatchingExecutor.scala:55)
at akka.dispatch.BatchingExecutor$BlockableBatch.$anonfun$run$1(BatchingExecutor.scala:92)
at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
at scala.concurrent.BlockContext$.withBlockContext(BlockContext.scala:81)
at akka.dispatch.BatchingExecutor$BlockableBatch.run(BatchingExecutor.scala:92)
at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:41)
at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(ForkJoinExecutorConfigurator.scala:49)
at akka.dispatch.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at akka.dispatch.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at akka.dispatch.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at akka.dispatch.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Any quick pointers will be really helpful
Levi Ramsey was right it was because of TakeZoe lib which we were using. We were creating client for every new request and not closing it. Finally we created a connection pool with limited active connections and it worked.
I have a process with two threads.
First thread is doing async work - it waits for IO on descriptors and timer events in epoll_wait.
Second thread is doing a lot of IO/memory work - it reads data from disk, process it in memory, allocates a lot of new memory, write it to disk and so on.
The problem is that first thread blocks in epoll_wait for much longer time, then was requested in timeout for epoll_wait(e.g. timeout was specified as 1500 ms and actually return from epoll_wait occures in 10 seconds).
This behavior I can reliably reproduce in virtual machine(VirtualBox with Ubuntu 16.04).
Example of behavior from GDB:
Thread 2.1 "se.real" hit Breakpoint 1, boost::asio::detail::epoll_reactor::run (this=0x826ebe0, block=true, ops=...) at /opt/com/include/boost/158/boost/asio/detail/impl/epoll_reactor.ipp:392
392 in /opt/com/include/boost/158/boost/asio/detail/impl/epoll_reactor.ipp
16:36:38.986826839
$17 = 1945
Thread 2.1 "se.real" hit Catchpoint 3 (call to syscall epoll_wait), 0xf7fd8be9 in __kernel_vsyscall ()
16:36:38.992081396
<INSIDE KERNEL>
Thread 2.1 "se.real" hit Catchpoint 3 (returned from syscall epoll_wait), 0xf7fd8be9 in __kernel_vsyscall ()
16:36:54.681444938
Breakpoint 1 is set to instruction prior to call epoll_wait, printed argument is timeout argument value(1945 ms).
Printed time is time from shell date +"%T.%N" command.
Catchpoint 3 is syscall catchpoint for epoll_wait syscall(first for enter, second for return).
We can easily see that we have spent in kernel for ~ 16 seconds, when 1945 ms were requested.
I have gathered perf record with -e 'sched:*' events from another reproduction. And I perfectly see:
se.real 4277 [001] 113049.144027: sched:sched_switch: prev_comm=se.real prev_pid=4277 prev_prio=120 prev_state=t|K ==> next_comm=strace next_pid=4142 next_prio=120
se.real 4277 [001] 113056.407952: sched:sched_stat_runtime: comm=se.real pid=4277 runtime=153767 [ns] vruntime=409222246640 [ns]
No any other sched event for thread 4277(first thread with async IO and epoll_wait) for ~7 seconds. In mean time there are a lot of sched activity between this events. This activity includes both second thread(thread with a lot of IO/memory work), swapper/kswapd, and other userspace processes.
The question is what I can do to give a chance for running first thread?
Update: changing scheduling policy to SCHED_FIFO for process doesn't solve problem - I'm still able stably reproduce the issue.
Do you think that a latency of 50 msec are normal in Linux System?
I have a program with many threads, one thread is controlling the movement of an object with a motor and photocells.
I have made many thing to get minimun latency, but always get 50 msec that cause a position error in the object.
Things I did:
- nice function to -20
- Thread priority of photeocell control thread: SCHED FIFO, 99
- Kernel configuration: CONFING_PREEMPT=y
- mlockall (MCL_CURRENT | MCL_FUTURE);
Many times, I lose 50 msec waiting for a photocell. I think that the problema is not another of
my thread, but process in the kernel.
Is posible reduced this latency? Is posible to know who is getting this 50 msec extra?
The thread that is controlling photocells make many "read" functions. Can this generate problems?
/**********/
At now the situation is:
There is only one thread running an infinite empty loop, only looking for time at start od the loop an at the end of the loop.
No acces to disk, no acces to GPIO, no serial ports, nothing.
The loop spend 50 milisecond many of the times.
I have not set cpuaffinity, my processor has only one nucleus.
I have been making test in my program.
This is the code in the main function, before the program star the threads, that cause de 50 mseg latency:
struct sched_param lsPrio;
lsPrio.sched_priority = 1;
if (sched_setscheduler (0, SCHED_FIFO, &lsPrio) != 0)
printf ("FALLO sched_set\n");
if I comment this lines the latency is reduced about 1 mseg.
Why this lines cause latency?
I don't understand behavior of glassfish v3.1.2.
I run my java web-application with such glassfish thread-pool parameters:
Class Name: com.sun.grizzly.http.StatsThreadPool
Max Queue Size: 4096
Max Thread Pool Size: 10
Min Thread Pool Size: 10
Idle Thread
Timeout: 900
Then I send many requests to my servlet. The logic of my servlet is like this:
//do some action
Thread.currentThread().sleep(5000);
Netbeans profiler shows these results in threads window:
http://s8.postimage.org/5hupqk4ad/profiler.png
It seems that all 10 threads were created, but only 5 can run simultaneously.
Of course I want to use max number of threads simultaneously.
Can somebody explain such behavior and suggest how to fix it.
Tell me if you need more information.
Thanks
Try to check your client side, may be you have restrictions there.
We have an application that is undergoing performance testing. Today, I decided to take a dump of w3wp & load it in windbg to see what is going on underneath the covers. Imagine my surprise when I ran !threads and saw that there are 640 background threads, almost all of which seem to say the following:
OS Thread Id: 0x1c38 (651)
Child-SP RetAddr Call Site
0000000023a9d290 000007ff002320e2 Microsoft.Practices.EnterpriseLibrary.Caching.ProducerConsumerQueue.WaitUntilInterrupted()
0000000023a9d2d0 000007ff00231f7e Microsoft.Practices.EnterpriseLibrary.Caching.ProducerConsumerQueue.Dequeue()
0000000023a9d330 000007fef727c978 Microsoft.Practices.EnterpriseLibrary.Caching.BackgroundScheduler.QueueReader()
0000000023a9d380 000007fef9001552 System.Threading.ExecutionContext.runTryCode(System.Object)
0000000023a9dc30 000007fef72f95fd System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
0000000023a9dc80 000007fef9001552 System.Threading.ThreadHelper.ThreadStart()
If i had to give a guess, I'm thinkign that one of these threads are getting spawned for each run of our app - we have 2 app servers, 20 concurrent users, and ran the test approximately 30 times...it's in the neighborhood.
Is this 'expected behavior', or perhaps have we implemented something improperly? The test ran hours ago, so i would have expected any timeouts to have occurred already.
Edit: Thank you all for your replies. It has been requested that more detail be shown about the callstack - here is the output of !mk from sosex.dll.
ESP RetAddr
00:U 0000000023a9cb38 00000000775f72ca ntdll!ZwWaitForMultipleObjects+0xa
01:U 0000000023a9cb40 00000000773cbc03 kernel32!WaitForMultipleObjectsEx+0x10b
02:U 0000000023a9cc50 000007fef8f5f595 mscorwks!WaitForMultipleObjectsEx_SO_TOLERANT+0xc1
03:U 0000000023a9ccf0 000007fef8f59f49 mscorwks!Thread::DoAppropriateAptStateWait+0x41
04:U 0000000023a9cd50 000007fef8e55b99 mscorwks!Thread::DoAppropriateWaitWorker+0x191
05:U 0000000023a9ce50 000007fef8e2efe8 mscorwks!Thread::DoAppropriateWait+0x5c
06:U 0000000023a9cec0 000007fef8f0dc7a mscorwks!CLREvent::WaitEx+0xbe
07:U 0000000023a9cf70 000007fef8fba72e mscorwks!Thread::Block+0x1e
08:U 0000000023a9cfa0 000007fef8e1996d mscorwks!SyncBlock::Wait+0x195
09:U 0000000023a9d0c0 000007fef9463d3f mscorwks!ObjectNative::WaitTimeout+0x12f
0a:M 0000000023a9d290 000007ff002321b3 *** ERROR: Module load completed but symbols could not be loaded for Microsoft.Practices.EnterpriseLibrary.Caching.DLL
Microsoft.Practices.EnterpriseLibrary.Caching.ProducerConsumerQueue.WaitUntilInterrupted()(+0x0 IL)(+0x11 Native)
0b:M 0000000023a9d2d0 000007ff002320e2 Microsoft.Practices.EnterpriseLibrary.Caching.ProducerConsumerQueue.Dequeue()(+0xf IL)(+0x18 Native)
0c:M 0000000023a9d330 000007ff00231f7e Microsoft.Practices.EnterpriseLibrary.Caching.BackgroundScheduler.QueueReader()(+0x9 IL)(+0x12 Native)
0d:M 0000000023a9d380 000007fef727c978 System.Threading.ExecutionContext.runTryCode(System.Object)(+0x18 IL)(+0x106 Native)
0e:U 0000000023a9d440 000007fef9001552 mscorwks!CallDescrWorker+0x82
0f:U 0000000023a9d490 000007fef8e9e5e3 mscorwks!CallDescrWorkerWithHandler+0xd3
10:U 0000000023a9d530 000007fef8eac83f mscorwks!MethodDesc::CallDescr+0x24f
11:U 0000000023a9d790 000007fef8f0cbd2 mscorwks!ExecuteCodeWithGuaranteedCleanupHelper+0x12a
12:U 0000000023a9da20 000007fef945e572 mscorwks!ReflectionInvocation::ExecuteCodeWithGuaranteedCleanup+0x172
13:M 0000000023a9dc30 000007fef7261722 System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)(+0x60 IL)(+0x51 Native)
14:M 0000000023a9dc80 000007fef72f95fd System.Threading.ThreadHelper.ThreadStart()(+0x8 IL)(+0x2a Native)
15:U 0000000023a9dcd0 000007fef9001552 mscorwks!CallDescrWorker+0x82
16:U 0000000023a9dd20 000007fef8e9e5e3 mscorwks!CallDescrWorkerWithHandler+0xd3
17:U 0000000023a9ddc0 000007fef8eac83f mscorwks!MethodDesc::CallDescr+0x24f
18:U 0000000023a9e010 000007fef8f9ae8d mscorwks!ThreadNative::KickOffThread_Worker+0x191
19:U 0000000023a9e330 000007fef8f59374 mscorwks!TypeHandle::GetParent+0x5c
1a:U 0000000023a9e380 000007fef8e52045 mscorwks!SVR::gc_heap::make_heap_segment+0x155
1b:U 0000000023a9e450 000007fef8f66139 mscorwks!ZapStubPrecode::GetType+0x39
1c:U 0000000023a9e490 000007fef8e1c985 mscorwks!ILCodeStream::GetToken+0x25
1d:U 0000000023a9e4c0 000007fef8f594e1 mscorwks!Thread::DoADCallBack+0x145
1e:U 0000000023a9e630 000007fef8f59399 mscorwks!TypeHandle::GetParent+0x81
1f:U 0000000023a9e680 000007fef8e52045 mscorwks!SVR::gc_heap::make_heap_segment+0x155
20:U 0000000023a9e750 000007fef8f66139 mscorwks!ZapStubPrecode::GetType+0x39
21:U 0000000023a9e790 000007fef8e20e15 mscorwks!ThreadNative::KickOffThread+0x401
22:U 0000000023a9e7f0 000007fef8e20ae7 mscorwks!ThreadNative::KickOffThread+0xd3
23:U 0000000023a9e8d0 000007fef8f814fc mscorwks!Thread::intermediateThreadProc+0x78
24:U 0000000023a9f7a0 00000000773cbe3d kernel32!BaseThreadInitThunk+0xd
25:U 0000000023a9f7d0 00000000775d6a51 ntdll!RtlUserThreadStart+0x1d
Yes, the caching block has some - issues - with regard to the scavenger threads in older versions of Entlib, particularly if things are coming in faster than the scavenging settings let them come out.
This was completely rewritten in Entlib 5, so that now you'll never have more than two threads sitting in the caching block, regardless of the load, and usually it'll only be one.
Unfortunately there's no easy tweak to change the behavior in earlier versions. The best you can do is change the cache settings so that each scavenge will clean out more items at a time so not as many scavenge requests need to get scheduled.
640 threads is very bad for performance. If they are all waiting for something, then I'd say it's a fair bet that you have a deadlock and they will never exit. If they are all running (not waiting)... well, with 600+ threads on a 2 or 4 core processor none of them will get enough time slices to run very far! ;>
If your app is set up with a main thread that waits on the thread handles to find out when the threads exit, and the background threads get caught up in a loop or in a wait state and never exit the thread proc, then the process and all of its threads will never exit.
Check your thread code to make sure that every threadproc has a clear path to exit the threadproc. It's bad form to write an infinite loop in a background thread on the assumption that the thread will be forcibly terminated when the process shuts down.
If the background thread code spins in a loop waiting for an event handle to signal, make sure that you have some way to signal that event so that the thread can perform a normal orderly exit. Otherwise, you need to write the background thread to wait on multiple events and unblock when any one of the events signals. One of those events can be the activity that the background thread is primarily interested in and the other can be a shutdown event.
From the names of things in the stack dump you posted, it would appear that the thread is waiting for something to appear in the ProducerConsumerQueue. Investigate how that queue object is supposed to be shut down, probably on the producer side, and whether shutting down the queue will automatically release all consumers that are waiting on that queue.
My guess is that either the queue is not being shut down correctly or shutting it down does not implicitly release the consumers that are waiting on it. If the latter case, you may need to pump a terminate message through the queue to wake up all the consumers waiting on that queue and tell them to break out of their wait loop and exit.
You have an major issue. Every Thread occupies 1MB of stack and there is significant cost paid for Context Switching every thread in and out. Especially it becomes worst with managed code because every time GC has to run , it would have walk the threads stack to look for roots and when these threads are paged to the disk the cost to read from the disk is expensive,which adds up Perf issue.
Creating threads are Bad unless you know what you are doing? Jeffery Richter has written in detail about this.
To solve the above issue I would look what these threads are blocked on and also put a break-point on Thread Create (example sxe ct within windbg)
And later rearchitect from avoid creating threads , instead use the thread pool.
It would have been nice to some callstacks of these threads.
In Microsoft Enterprise Library 4.1, the BackgroundScheduler class creates a new thread each time an object is instantiated. It will be fixed in version 5.0. I do not know enough of this Microsoft Library to advise you how to avoid that behavior, but you may try the beta version: http://entlib.codeplex.com/wikipage?title=EntLib5%20Beta2