I would say that code with parallel computations + cypari2 should not
be merged (as cypari2 does not support it).
If you need parallel + PARI then use the C library directly with the
appropriate threads locks.
If the problem comes from somewhere else, then it would better be sorted
out.
Best
Vincent
Le 16/05/2022 à 06:42, 'Travis Scrimshaw' via sage-devel a écrit :
That sure seems like it. So what should we do about the ticket? Would there
be opposition to merging this piece of code, as there doesn't seem like
there is a fix coming for the likely underlying cypari bug anytime soon?
Best,
Travis
On Sunday, May 15, 2022 at 4:14:31 PM UTC+9 vdelecroix wrote:
Probably related to https://github.com/sagemath/cypari2/issues/107 ?
Le 15/05/2022 à 05:06, 'Travis Scrimshaw' via sage-devel a écrit :
Hi everyone,
On ticket #30423 <https://trac.sagemath.org/ticket/30423>, Dan, Willie,
and I have been working on a parallel-computation based implementation
for
computing F-matrices that are used in math physics. However, we have been
seeing some doctest failures sporadically that involve segfaults and
linked-list corruption from (cy)PARI. Here are the logs from testing with
the first and the last having full tracebacks.
http://sporadic.stanford.edu/badlog-match
http://sporadic.stanford.edu/badlog
http://sporadic.stanford.edu/badlog1
http://sporadic.stanford.edu/badlog2
http://sporadic.stanford.edu/badlog3
The first question would be if anyone has an idea about what is causing
this. I have this impression that PARI is thread-safe, but I am wondering
if cypari is also thread/parallel-safe or if there are any specific
things
that we should be careful about. (We’ve already had to work around a
pickling issue with polynomials IIRC.)
Second question is that because this is a Heisenbug and I suspect it is
something upstream (and so far, nobody has been able to reproducing it
during an interactive version of Sage), I was wondering what the policy
would be for merging the ticket. I recall in the past that we have merged
tickets with Heisenbugs with followup tickets noting the behavior, but I
am
not 100% sure about that (and I wouldn’t necessarily know how to find any
explicit examples). I was wondering if we could merge the ticket in an
early beta version so that many people/systems can test it to see if it
becomes more reproducible; of course this is assuming that the build bots
are not consistent in reproducing this. Should we just mark any offending
test(s) as “# known bug” and is there some general policy about this?
Thanks,
Travis
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