Comparing versions at leisure, but this same issue dates back in slight variations to since I started crunching back in 2007, with different symptoms depending on build characteristics and afflicted system ( OS version, #cores, and GPU or CPU). You be looking for a history on the boinc_exit() function. Don;t think it ever had the wait after terminateprocess, so IO cancellations are likely depending on timing/chance.
------------------------------------------------------------------------------------------------------ Jason Richard Groothuis bSc(compSci) ------------------------------------------------------------------------------------------------------ Date: Sat, 11 Jul 2015 20:07:56 +0000 From: [email protected] To: [email protected]; [email protected]; [email protected] Subject: Re: [boinc_dev] Client: race condition on stderr.txt invalidates Milkyway tasks The Milkyway application we are mostly observing this with is milkyway_separation__modified_fit_1.36_windows_x86_64__opencl_nvidia_101.exe, which was deployed to their server on 6 Oct 2014, 20:18:34 UTC - the internal signature says "API_VERSION_6.13.0" On Saturday, 11 July 2015, 20:55, Jason Groothuis <[email protected]> wrote: "Perhaps the exit process has been invoked in the Milkyway app, but not all consequent OS functions have completed in time."Correct, since the TermnateProcess() call, which is asynchronous and so returns immediately without necessarily doing anything, is missing the WaitForSingleObject() on the Current process after it. The process resources will cleanup as part of OS garbage collection *sometime* down the road.Doubting the accuracy of the MSDN documentation on these functions is fine, but wondering why it doesn;t work as expected when you ignore it, is just odd. On Saturday, 11 July 2015, 20:09, Jason Groothuis <[email protected]> wrote: Not sure how much detail you'd like on the situation. (Can provide much more) It's a result of buffered IO implemented in multithreaded C Runtimes, in some situations using deferred procedure calls. Internal helper threads are being killed before commits are completed.least desirable partial workaround (but helps): - disable buffered IO by linking the application with the ms supplied COMMODE.OBJProbably Better, but not tested:- initiate a low level _commit() and add the missing WaitForSingleObject() after the TerminateProcess Call,Best:- do a low level _comit() and check the file modification time updated, then preferably use a friendly means of exit that allows DLL/Thread cleanup, closing threads/processes using sentinel flags, like while(!done) instead of while(1) with kills.------------------------------------------------------------------------------------------------------Jason Richard Groothuis bSc(compSci)-------------------------------------------------------------- ----------------------------------------> Date: Sat, 11 Jul 2015 11:30:32 -0700> From: [email protected]> To: [email protected]; [email protected]> Subject: Re: [boinc_dev] Client: race condition on stderr.txt invalidates Milkyway tasks> > Richard:> Can you please ask him to set <task_deb ug> as well?> > I have no theories about what could cause this.> The BOINC client learns that a job is finished when its process has exited,> and by that time all files are closed and locks released> (I'm assuming the MW@h app is single-process - is that correct?)> > In this case, when the job finishes, the client successfully reads stderr.txt> (otherwise <stderr_txt> would be absent or there would be an error message)> but it's empty.> This would be the case, e.g., if the writing process hadn't exited yet> and its stderr buffer wasn't flushed.> But the process has exited.> > Anyone have any ideas?> > -- David> > On 09-Jul-2015 7:42 AM, Richard Haselgrove wrote:> > User Keith Myers (UID 147145 at http://milkyway.cs.rpi.edu/milkyway/index.php) has > > asked for my help in identifying task failures at Milkyway.> >> > At my suggestion, he installed Windows client v7.6.2, and the attached message log > > extracts show the enhanced <slot_debug> output that helped identify the CM S-dev > > problem.> >> > In both cases, the task under scrutiny> >> > (1) de_fast_15_3s_136_sim1Jun1_1_1434554402_7775504_0, > > http://milkyway.cs.rpi.edu/milkyway/result.php?resultid=1181200273> >> > (2) ps_fast_15_3s_136_sim1Jun1_1_1434554402_7806437_0, > > http://milkyway.cs.rpi.edu/milkyway/result.php?resultid=1181298220> >> > was declared 'Validate error', and the <stderr_txt> section is empty. In the > > special case of Milkyway@Home, these two observations are linked, because the > > science result is returned in stderr, not a separate upload file.> >> > Also in both cases, the <slot_debug> log contains> >> > [slot] failed to remove file slots/x/stderr.txt: unlink() failed> >> > between 'handle_exited_app()' and 'Computation for task ... finished'> >> > It appears that there is a race condition, whereby BOINC tries (and fails) to > > delete stderr.txt before the operating system has released the write lock. This > > (I'm presuming) also explains why the file appears empty when read off the disk > > for incorporation into the client_state structure in memory, prior to reporting > > the completed task to the project.> >> > In order the preserve the scientific result at Milkyway (and debug and other > > useful information at other projects), the client should not initiate > > 'handle_exited_app()' until it has confirmed that the write lock on stderr.txt has > > been released.> >> >> > Log 1 also shows that the additional safeguards on cleaning out slots are working > > properly: if both handle_exited_app() and get_free_slot() fail to delete the file, > > the next task isn't started in the not-empty slot (11), but in slot 14 inste ad. > > And when slot 11 is tested again at the next get_free_slot(), the delete succeeds > > and the now-empty slot is reused.> > _______________________________________________> boinc_dev mailing list> [email protected]> http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_dev> To unsubscribe, visit th e above URL and> (near bottom of page) enter your email address. _______________________________________________boinc_dev mailing [email protected]http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_devTo unsubscribe, visit the above URL and(near bottom of page) enter your email address. _______________________________________________boinc_dev mailing [email protected]http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_devTo unsubscribe, visit the above URL and(near bottom of page) enter your email address. _______________________________________________ boinc_dev mailing list [email protected] http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_dev To unsubscribe, visit the above URL and (near bottom of page) enter your email address.
