IPC and pthread condition variable bug

[Sikorski Grzegorz-VBFM67]

Hello,

I have tried to build an application with queues in UNIX flavor (using msgget API). I have successfully ran cygwin server and enabled IPC. The program works if I use 2-3 queues to send messages between threads (single thread reads from one queue, multiple threads can write to any queue). Although if I try to create more than 3 queues, the application behaves very strange - some read queue operations (msgrcv without IPC_NOWAIT flag set) fail randomly (returns success even if there is no message in the queue or returns undefined errors).

I also tried to implement my own IPC, without cygwin server IPC. The code, which has been successfully tested on Solaris 5.10 platform and runs there normally, under cygwin fails randomly. I have investigated that the problem is with pthread condition variables and timedout wait: pthread_cond_wait and pthread_cond_timedwait returns undefined values (none of valid error codes). This situation occurs if I operate on many condition variables (more than 3). If I use only 3 condition variables, there is no errors and my IPC works absolutely fine.

Best regards,
Grzegorz Sikorski
Astro Infrastructure
VPM QUICC Team
+48122988863
grzegorz.sikorski@motorolasolutions.com
 
Motorola Polska Electronics  Sp.z.o.o
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