[cmake-developers] Parallel ctest issues on the MinGW-w64/MSYS2 platform

[Alan W. Irwin]

On 2016-03-29 22:46+0200 Nils Gladitz wrote:

> On 29.03.2016 21:39, Alan W. Irwin wrote:
>> One of the PLplot developers, Arjen Markus, has just reported to me
>> that ctest -j4 for PLplot hangs on his MinGW-w64/MSYS2 platform while
>> ctest works fine. This issue occurred for the
>> mingw64/mingw-w64-x86_64-cmake 3.4.1-1 package version of ctest.exe,
>> and the PLplot build was done with the "MSYS Makefiles" generator. In
>> contrast to the MinGW-w64/MSYS2 platform case, ctest -j4 works fine
>> for the Linux case.
>> 
>> Has anyone else here had similar difficulties OR success with the
>> parallel ctest option on the MinGW-w64/MSYS2 platform?
>
> Afair there are sporadic issues with the cygwin runtime (on which msys/msys2 
> is based) in the process handling code of kwsys (used by cmake).
> The code is used by e.g. execute_process() and also ctest for test execution.
>
> I think the issue is due to how pipes are implemented by the runtime.
> From what I remember rsync also suffers from this.
>
> Also having Kaspersky installed (even when paused) seems to make these hangs 
> more likely.

Thanks, Nils, for that information.  Could this issue be related to
the Cygwin unreliability mentioned in
<http://cygwin.com/cygwin-ug-net/highlights.html> where they say "In
summary, current Windows implementations make it impossible to
implement a perfectly reliable fork, and occasional fork failures are
inevitable."?

In any case, whatever the issue is, Arjen appears (so far) to have
found a reliable reproducer with the -j option for ctest.  So I hope
others here try the -j option for ctest on MinGW-w64/MSYS2 platforms
for their favorite projects to get a better idea of how widespread
this issue is.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
__________________________

Linux-powered Science
__________________________