Re: EPICS thread problem on cygwin-x86

[Eric Norum <norume@aps.anl.gov>]

On Apr 27, 2007, at 1:58 PM, Mark Rivers wrote:

> Eric,
>
> 1) Does putting the epicsThreadSleep(.001); into the thread wrapper
> function that actually invokes the EPICS thread fix things?
>
> No.  I have simplified the program even more, eliminating the
> epicsEvent.  I just spawn a thread that either returns immediately or
> sleeps for .001 second.  The wrapper function now sleeps for 5 seconds
> after spawning the thread.  It still behaves the same, i.e. if the
> spawned thread sleeps for .001 second all is well, and the calling
> function sleeps for 5 seconds and prints a message. If it does not  
> sleep
> then it crashes.

I think that I wasn't clear enough about where I meant for the delay  
to go.
Here's the code in /src/libCom/osi/os/posix/osdThread.c which I meant  
when I referred to the 'wrapper' routine:

static void * start_routine(void *arg)
{
    epicsThreadOSD *pthreadInfo = (epicsThreadOSD *)arg;
    int status;
    int oldtype;
    sigset_t blockAllSig;

    sigfillset(&blockAllSig);
    pthread_sigmask(SIG_SETMASK,&blockAllSig,NULL);
    status = pthread_setspecific(getpthreadInfo,arg);
    checkStatusQuit(status,"pthread_setspecific","start_routine");
    status = pthread_setcanceltype 
(PTHREAD_CANCEL_ASYNCHRONOUS,&oldtype);
    checkStatusQuit(status,"pthread_setcanceltype","start_routine");
    status = mutexLock(&listLock);
    checkStatusQuit(status,"pthread_mutex_lock","start_routine");
    ellAdd(&pthreadList,&pthreadInfo->node);
    pthreadInfo->isOnThreadList = 1;
    status = pthread_mutex_unlock(&listLock);
    checkStatusQuit(status,"pthread_mutex_unlock","start_routine");

    (*pthreadInfo->createFunc)(pthreadInfo->createArg);

    epicsExitCallAtThreadExits ();

    free_threadInfo(pthreadInfo);
    return(0);
}

Does putting the delay just before the free_threadInfo call fix things?

> 2) Have you tried running this under gdb to see where the crash  
> occurs?
>
> I have found that gdb under Cygwin does not run the threaded EPICS
> applications at all.  Maybe I'm doing something wrong, but what  
> works on
> Linux does not work on Cygwin.  Furthermore, Cygwin does not produce a
> useful core file.  It produces a file called, in this case
> "threadTest.exe.stackdump", but it simply contains:
>
> $ cat threadTest.exe.stackdump
> Exception: STATUS_ACCESS_VIOLATION at eip=004A05B6
> eax=DF0DF046 ebx=004E6F60 ecx=6112CB58 edx=005A2DC0 esi=005A2DC0
> edi=610E30A0
> ebp=0022EDD8 esp=0022EDD4
> program=j:\epics\devel\threadTest\bin\cygwin-x86\threadTest.exe, pid
> 4028, thread main
> cs=001B ds=0023 es=0023 fs=003B gs=0000 ss=0023
> Stack trace:
> Frame     Function  Args
> 0022EDD8  004A05B6  (004E6F60, 005A2DC0, 0022EE08, 005A2DC8)
> 0022EDF8  004918A7  (610E30A0, 004D94F4, 004D9747, 6110A4F0)
> 0022EE28  0049220E  (004C9438, 0000000A, 00020000, 00401520)
> 0022EE48  00401593  (00543BD8, 0022EEE8, 00000000, 005407A4)
> 0022EEF8  00418070  (61157780, FFFFFFFF, 00000000, 004015F3)
> 0022EF18  0040161E  (00000002, 61157668, 00540090, 77FA88F0)
> 0022EFD8  61004DD2  (0022EFF0, 00000000, 0022F221, 33323430)
> 0022FF88  6100594F  (00000000, 00000000, 00000000, 00000000)
> End of stack trace
Hmmmmm...
not too useful.

--
Eric Norum <norume@aps.anl.gov>
Advanced Photon Source
Argonne National Laboratory
(630) 252-4793