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Subject: IPC and pthread condition variable bug
Date: Fri, 15 Apr 2011 11:48:45 +0100
Message-ID: <1F22C5AA2CC2C14F943CBEAAF3E385D4020C6A4E@zuk35exm66.ds.mot.com>
From: "Sikorski Grzegorz-VBFM67" <grzegorz DOT sikorski AT motorolasolutions DOT com>
To: <cygwin AT cygwin DOT com>
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Hello,

I have tried to build an application with queues in UNIX flavor (using msgg=
et 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 rando=
mly (returns success even if there is no message in the queue or returns un=
defined 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 a=
nd pthread_cond_timedwait returns undefined values (none of valid error cod=
es). This situation occurs if I operate on many condition variables (more t=
han 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 DOT sikorski AT motorolasolutions DOT com
=A0
Motorola Polska Electronics=A0 Sp.z.o.o
Bobrzynskiego 46,=20
30-381 Krakow, Poland
KRS 0000146875 - Poland
VAT No: PL6772135826
Share capital: 4,600,000 PLN=A0=20
Details of Motorola's subsidiaries in the EU/EEA can be found at: v www.mot=
orolasolutions.com/XU-EN/About/Subsidiaries=20
=20


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