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Re: [SCTP-Discussion] Problems facing in multithreading.


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  • From: Thomas Dreibholz <dreibh AT exp-math.uni-essen.de>
  • To: discussion AT sctp.de
  • Subject: Re: [SCTP-Discussion] Problems facing in multithreading.
  • Date: Fri Jul 12 16:22:01 2002
  • List-id: SCTP Discussions <discussion.sctp.de>
  • Organization: University of Essen, Institute for Experimental Mathematics

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Am Donnerstag, 11. Juli 2002 05:52 schrieben Sie:
> Hi,
>
> We are using the sctplib (sctplib-1.0.0-pre16) for
> a multithreaded application. The sctpsend is in one thread
> whereas the callbacks are in another thread. binary is core dumping
> randomly because of some synchronization problem (we suspect).
>
> From the code we understood that it is because of the use of some
> global variables (currentAssociation in distribution.c).
> we tried putting locks in send and receive
> but now we are facing core dump in timer compare. we feel that this is
> also because of the same reason.
>
> did anyone face this problem before, then please let us know how
> u solved it. or is it because of improper usage of the library.

The sctplib itself is not thread-safe, but the socket API library for the
sctplib (in the socketapi/ directory of the sctplib distribution) is
thread-safe. Therefore, this is the easiest way to write threaded programs.

If you need thread-safety for the sctplib itself, you have to take care for
it yourself. But this is also not difficult:

- - Create a global mutex.
- - Write functions lock(void* mutex) and unlock(void* mutex) to obtain and
release the mutex.
- - Every thread must obtain the mutex before calling any sctplib function.
- - After calling the function, the mutex must be released.
- - Use sctp_extendedEventLoop(lock,unlock,mutex) instead of sctp_eventLoop().
sctplib now uses your lock() and unlock() functions to obtain and release the
mutex.
- - For the loop to call sctp_extendedEventLoop(), use an own thread.

As an example how to realize this, see sctpsocketmaster.cc (the event loop
thread) and the other files in the socketapi/ directory.


Best regards
- --
=======================================================================
Dipl.-Inform. Thomas Dreibholz

University of Essen, Room ES210
Inst. for Experimental Mathematics Ellernstraße 29
Computer Networking Technology Group D-45326 Essen/Germany
- -----------------------------------------------------------------------
E-Mail:
dreibh AT exp-math.uni-essen.de
Homepage: http://www.exp-math.uni-essen.de/~dreibh
=======================================================================

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