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Message-ID: <518AB9F2.6050501@cs.utoronto.ca>
Date: Wed, 08 May 2013 16:47:46 -0400
From: Ryan Johnson <ryan DOT johnson AT cs DOT utoronto DOT ca>
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To: cygwin AT cygwin DOT com
Subject: Re: printf + pthreads+gdb+mintty = hang?
References: <5189627F DOT 3050801 AT cs DOT utoronto DOT ca> <20130508183617 DOT GA8072 AT ednor DOT casa DOT cgf DOT cx>
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On 08/05/2013 2:36 PM, Christopher Faylor wrote:
> On Tue, May 07, 2013 at 04:22:23PM -0400, Ryan Johnson wrote:
>> Hi all,
>>
>> Running the attached STC inside gdb hangs (zero CPU util, have to kill
>> gdb from Task Manager, killing a.exe doesn't cut it).
>>
>> Compile line used: g++ -Wall -g -mthreads -DBUG bug.cpp
>>
>> I currently have the following package versions:
>> cygwin-1.7.18(0.263/5/3) 2013-04-19
>> mintty-1.1.3-1
>> gdb-7.6.50-1
>> gcc-4.5.3-3
>>
>> The problem seems to be related to threads calling fprintf inside gdb,
>> it runs fine from the command line, or with printf instead; both fprintf
>> and printf sometimes trigger "warning: SuspendThread failed. (winerr 6)"
>> (not sure if that matters).
>>
>> Known issue? Easy workaround? New bug?
> Known, long-standing issue.  I put a workaround in the latest snapshot.
Hmm. The STC still hangs about 25% of the time (down from ~100%), so 
things are improved but not fixed.

Also, when I hit an assertion failure in my code, gdb successfully 
breaks in at my breakpoint on abort()---which used to hang---but then 
hangs as soon as I say "up 2" to see the actual source of the assertion 
failure. Unfortunately, I haven't been able to distill that one down to 
a reasonable STC: just arranging for a threaded toy app to call abort 
from multiple threads simultaneously doesn't seem to tickle the bug.

Ryan


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