I read many posts here and on other sites, but can not find the problem creating my Error:
I use an AsyncTask because I want to easily manipulate the UI Thread before and after Execution.
In doInBackground I create a ThreadPoolExecutor and execute Runnables.
If I only execute 1 Runnable with the Executor, there is no Problem, but if I execute another Runnable I get following Error:

06-26 18:00:42.288: A/libc(25073): Fatal signal 11 (SIGSEGV) at 0x7f486162 (code=1), thread 25106 (pool-1-thread-2)
06-26 18:00:42.304: D/dalvikvm(25073): GC_CONCURRENT freed 119K, 2% free 8908K/9056K, paused 4ms+4ms, total 45ms
06-26 18:00:42.327: I/System.out(25073): In Check All with Prefix: a and Length: 4
06-26 18:00:42.390: I/DEBUG(126): *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***  ***
06-26 18:00:42.390: I/DEBUG(126): Build fingerprint: 'google/yakju/maguro:4.2.2/JDQ39/573038:user/release-keys'
06-26 18:00:42.390: I/DEBUG(126): Revision: '9'
06-26 18:00:42.390: I/DEBUG(126): pid: 25073, tid: 25106, name: pool-1-thread-2  >>>     de.uni_duesseldorf.cn.distributed_computing2 <<<
06-26 18:00:42.390: I/DEBUG(126): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 7f486162

...

06-26 18:00:42.538: I/DEBUG(126): memory map around fault addr 7f486162:
06-26 18:00:42.538: I/DEBUG(126):     60292000-60391000 
06-26 18:00:42.538: I/DEBUG(126):     (no map for address)
06-26 18:00:42.538: I/DEBUG(126):     bed14000-bed35000 [stack]

I set up the ThreadPoolExecutor like this:

// numberOfPackages: Number of Runnables to be executed
public void initializeThreadPoolExecutor (int numberOfPackages)
{
    int corePoolSize = Runtime.getRuntime().availableProcessors();
    int maxPoolSize = numberOfPackages;
    long keepAliveTime = 60;
    final BlockingQueue workingQueue = new LinkedBlockingQueue();
    executor = new ThreadPoolExecutor(corePoolSize, maxPoolSize, keepAliveTime, TimeUnit.SECONDS, workingQueue);
}

I have no clue, why it fails when starting the second Thread.
Maybe Memory Leaks?

Any Help appreciated.
Thanks in Advance