Hi Ludo and Mathieu! Ludovic Courtès <l...@gnu.org> writes:
> Hi! > > Mathieu Othacehe <othac...@gnu.org> skribis: > >> I noticed this error: https://ci.guix.gnu.org/eval/320682/log/raw. >> >> The following lines can be caused by having a multi-threaded program: >> (cuirass scripts evaluate) because of its par-for-each procedure, call >> "primitive-fork" in open-bidirectional-pipe of (guix inferior). >> >> warning: call to primitive-fork while multiple threads are running; >> further behavior unspecified. See "Processes" in the >> manual, for more information. >> >> Not sure that it could cause the observed hang, Ludo what do you think? > > As you write, the warning comes from ‘open-bidirectional-pipe’, added in > commit bd86bbd300474204878e927f6cd3f0defa1662a5. I noticed it back then > but as far as I could see, it was harmless (but definitely suboptimal): > > https://issues.guix.gnu.org/48007#11 Thanks for investigating it! I'm not yet very knowledgeable about POSIX threads and shortcomings, but this looks like a dangerous trap to have lying around :-). Is there an alternative implementation we could come up with that would avoid the potential problem (and warnings) entirely? Otherwise, if we are sure there are no practical problems in a multi-threaded scenario, I think a comment explaining the reasoning in the code (of why it's considered safe despite the warnings) and a test exercising the behavior would be in order to ensure it continues working as intended in the face of changes. Thoughts? Thanks again, Maxim
