From @zoffixznet

The previous day I ran make stresstest a ton of times and never had this failure. Today, we bumped [^1] nqp/MoarVM versions to bring in the latest changes and S17-procasync/no-runaway-file-limit.t started to segfault for me sporadically, about 30% of the time. So it's likely the issue is somewhere
within the nqp changes [^2] or the MoarVM changes [^3] that occurred between the version bumps.

Here's the conversation on the topic​: http://irclog.perlgeek.de/moarvm/2016-08-19#i_13053345

I found I the segfaults were more frequent (or at least appeared to be), when I modified the test [^4] to split its work among 30 promises (it's a 24-core box; Debian).

When running this line in Rakudo checkout, eventually it crashes​:

while RAKUDO_MAX_THREADS=40 ./perl6 -Ilib --ll-exception t/spec/S17-procasync/no-runaway-file-limit.t; do true; done

[1] rakudo/rakudo@25e9fd7
[2] Raku/nqp@2df0a06...b416158
[3] MoarVM/MoarVM@40948f6...31eccd7
[4] https://gist.github.com/zoffixznet/56542718459362a5990ad9b44b8edab6

From @zoffixznet

I've nuked my entire rakudo/ directory, built everything from scratch, and started to run the test in a loop in two terminals, while in third one I put the entire stresstest in a loop.

It's been an hour and 20 minutes by now and not a single failure, so I'll assume it was something dirty in my build directory.

@zoffixznet - Status changed from 'new' to 'rejected'

From @zoffixznet

Ehh... Reopening.

That was the clean run and everything was working great. The then pulled in a couple of changes, added some spectests, rebuilt rakudo and boom, the SEGV is back. Happens pretty regularly too​:

cpan@​perlbuild2​:~/CPANPRC/rakudo$ while RAKUDO_MAX_THREADS=40 ./perl6 -Ilib --ll-exception t/spec/S17-procasync/no-runaway-file-limit.t; do true; done
1..1
ok 1 - made it to the end
1..1
ok 1 - made it to the end
1..1
*** Error in `/home/cpan/CPANPRC/rakudo/install/bin/moar'​: double free or corruption (fasttop)​: 0x0000000005686d20 ***
Aborted
cpan@​perlbuild2​:~/CPANPRC/rakudo$ while RAKUDO_MAX_THREADS=40 ./perl6 -Ilib --ll-exception t/spec/S17-procasync/no-runaway-file-limit.t; do true; done
1..1
ok 1 - made it to the end
1..1
*** Error in `/home/cpan/CPANPRC/rakudo/install/bin/moar'​: double free or corruption (fasttop)​: 0x00000000058e4d20 ***
Aborted
cpan@​perlbuild2​:~/CPANPRC/rakudo$

@zoffixznet - Status changed from 'rejected' to 'open'

From @zoffixznet

This has been fixed by jnthn++ several months ago.

@zoffixznet - Status changed from 'open' to 'resolved'