From: "Lavrentiev, Anton (NIH/NLM/NCBI) [C]" <lavr@ncbi.nlm.nih.gov>
To: "cygwin@cygwin.com" <cygwin@cygwin.com>
Subject: RE: Possible race in SYSV IPC (semaphores)
Date: Mon, 26 Nov 2012 18:09:40 +0000
Message-ID: <5F8AAC04F9616747BC4CC0E803D5907D016FEA@MLBXv04.nih.gov>
References: <5F8AAC04F9616747BC4CC0E803D5907D012856@MLBXV09.nih.gov> <20121123113605.GN17347@calimero.vinschen.de> <20121123131020.GR17347@calimero.vinschen.de> <20121123133332.GU17347@calimero.vinschen.de> <20121123164404.GX17347@calimero.vinschen.de> <5F8AAC04F9616747BC4CC0E803D5907D0162C6@MLBXv04.nih.gov> <20121123172937.GA12624@calimero.vinschen.de> <5F8AAC04F9616747BC4CC0E803D5907D0162E7@MLBXv04.nih.gov> <20121123175903.GA11546@calimero.vinschen.de> <20121126125342.GA3800@calimero.vinschen.de>
In-Reply-To: <20121126125342.GA3800@calimero.vinschen.de>
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> I just checked in the change.

Thank you.  I will test it as soon as it's available in a snapshot.

> ...especially since I can't reproduce this.  I tried with cygserver
> before and after my patch and in both cases your semaphore testcase
> worked as expected with -d -l 7.

I see.  Maybe this will help.  My sequence of actions:

In an elevated cmd.exe, from Cygwin's /bin:

cygrunsrv.exe -I cygserver -x /usr/sbin/cygserver.exe -a "-d -l 7"
cygrunsrv.exe -S cygserver

In a regular cmd.exe:

a.exe

(this is my testcase that locks/unlocks the semaphores).
It never gets past iteration 1000.

Also, if I start cygserver just as a regular process (not as a background
thing), so that it logs right to the window, it does not lock up.

Anton Lavrentiev
Contractor NIH/NLM/NCBI