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Re: [RSPlib-Discusssion] fail-over problems


Chronological Thread 
  • From: Thomas Dreibholz <dreibh AT exp-math.uni-essen.de>
  • To: "Marjan Bozinovski" <marjanb AT cpk.auc.dk>, rsplib-discussion AT sctp.de
  • Cc: Michael Tüxen <Michael.Tuexen AT icn.siemens.de>, Michael Tüxen <Michael.Tuexen AT micmac.franken.de>
  • Subject: Re: [RSPlib-Discusssion] fail-over problems
  • Date: Mon Oct 21 12:52:00 2002
  • List-id: RSPlib Discussions <rsplib-discussion.sctp.de>
  • Organization: University of Essen, Institute for Experimental Mathematics
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Hi!

The cause of your problems have been found: Your program creates new
processes using fork() in line 518. This cannot work with the socket API and
it will never work. But you can use threads (see manual page of
pthread_create) to provide a similar functionality.

The sctplib's functionality is provided within an event loop. The user has to
continously call sctp_eventLoop() for the sctplib to be able to handle events
like timers and incoming data. This makes debugging easier but programming of
applications more complicated since you cannot simply do e.g. blocking
reads or writes. Using kernel-based protocols, the protocol's background
execution is hidden in the kernel. The socket API for the sctplib provides
this functionality by a second thread that runs the sctplib's event loop in
background. It uses mutexes to prevent both threads from causing
interferences.
Using fork(), you simply copy the whole process. This also includes kernel
file handles but not the socket API ones. Furthermore, all threads are
duplicated, including the SCTP instance and mutexes. Therefore, this totally
wrecks the socket API and sctplib management structures.


Since you are programming in C++, you can simply use my class Thread and the
classes Synchronizable and Condition to implement multiple threads. Just
inherit the class Thread and implement the method go(). Then, calling start()
starts your new thread.


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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