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<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>TimeLimit is included in smlnj-lib/Util. It uses the structure
Engine (same location) which itself relies on MLton.Itimer.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>10 seconds means nothing for my program. The time limit I set is
30 minutes.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The computation we perform in the application is pure mathematics
(no system calls expect to read or write some files to the disk, no dependency
against some particular FFI functions …). There is no direct use of the
setitimer() function and all the system calls that are performed internally by
MLton.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Please note that I also could not manage to extract a sample
program that reproduces the issue (I experienced it using Windows XP) … it
would have been too easy.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Wesley W. Terpstra
[mailto:wesley@terpstra.ca] <br>
<b>Sent:</b> Monday, August 31, 2009 12:39 AM<br>
<b>To:</b> Nicolas Bertolotti<br>
<b>Cc:</b> mlton@mlton.org<br>
<b>Subject:</b> Re: [MLton] Problem with the setitimer() emulation for MinGW<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>On Thu, Aug 27, 2009 at 5:06 PM, Nicolas Bertolotti <<a
href="mailto:Nicolas.Bertolotti@mathworks.fr">Nicolas.Bertolotti@mathworks.fr</a>>
wrote:<o:p></o:p></p>
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<p class=MsoNormal><span lang=EN-US>I am facing strange crashes of the MinGW
version of my application when using the TimeLimit structure</span><o:p></o:p></p>
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<p class=MsoNormal><br>
What is the "TimeLimit" structure? MLton exposes access to this
functionality only via the MLton.Itimer structure.<br>
<o:p></o:p></p>
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<p class=MsoNormal><span lang=EN-US>which relies on the setitimer
implementation (MLton compiler based on the current SVN sources).</span><span
lang=EN-US> </span><o:p></o:p></p>
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<p class=MsoNormal><br>
Can you provide a small demonstration program? Which version of Windows?<o:p></o:p></p>
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<p><span lang=EN-US>When I run a function using TimeLimit, the process actually
crashes about 10 seconds after the timer is initialized before the TimeLimit
call completes (even if the function I run through TimeLimit requires much less
than 10 seconds to complete).</span><o:p></o:p></p>
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<p class=MsoNormal>Is 10 seconds a special value in your program?<o:p></o:p></p>
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<p><span lang=EN-US>I noticed that the issue disappears if I comment out the
SetThreadPriority() call in the fixPriority() function (file
runtime/platform/mingw.c) and call :</span><o:p></o:p></p>
<p><span lang=EN-US>SetThreadPriority(GetCurrentThread(),
THREAD_PRIORITY_BELOW_NORMAL);</span><o:p></o:p></p>
<p><span lang=EN-US>instead from the main thread.</span><o:p></o:p></p>
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<p class=MsoNormal>Well, removing the line completely will just decrease the
responsiveness of the timers. Setting the main thread to higher priority will
decrease responsiveness even further. <br>
<br>
Is it possible that this decreased responsiveness masks some phenomenon in your
program which relates to this awfully special sounding 10s? A race condition
perhaps?<o:p></o:p></p>
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<p><span lang=EN-US>I can’t find out a reason why the system would let us
change the priority of the timer thread (the function returns TRUE) but adopt a
strange behavior after than but it definitely seems to be the case.</span><o:p></o:p></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'>I'm unconvinced that Windows
would have a bug like this.<br>
<br>
I get the vague impression that you might be using the MLton implementation of
setitimer directly... If that is the case, it probably is also the source of
your problems. The "signal handler" run by setitimer does not run in
the main thread, greatly restricting what one can safely do. MLton itself only
uses the handle to set a flag. I suggest you do the same.<o:p></o:p></p>
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