Hangs in cygwin 3.5.5-1: should 3.5.5-1 be rolled back?

Michael Soegtrop MSoegtrop@yahoo.de
Thu Jan 9 11:40:17 GMT 2025


Dear Cygwin Team,

I wanted to discuss the status of the hangs in cygwin 3.5.5-1 discussed 
in various threads here. I maintain the multi platform distribution of 
the Rocq/Coq Proof Assistant, and the day cygwin 3.5.5 was released (Dec 
20) our CI broke. Success rate of individual jobs is now roughly 50% 
with half failing with hangs at random points in the build. I verified 
that between the last good and the first bad CI run only cygwin itself 
changed (no other packages).

I looked into this locally with procmon and to me it looks like a call 
to make is finished, shuts down its threads but then never terminates. I 
can reproduce this fairly easily - a few minutes after an initial setup 
of about 1/2 hour, which can be reused. But it is not reproducible in a 
single run - it is a random effect. To make it reproducible, I have to 
repeat a build step until it fails. But this always happens fairly soon.

IMHO cygwin 3.5.5 is severely broken. Either a fix for these hangs also 
others experience should be released soon, or 3.5.5 should be rolled 
back until it is fixed.

I definitely cannot make a release for Rocq/Coq Platform with cygwin 3.5.5.

I want to take the opportunity to emphasize that in general cygwin is 
very stable and such issues are rare - I am running a nightly CI of 
Rocq/Coq Platform - a complex project which takes hours to build - with 
the latest cygwin since about 7 years and there were only few issues in 
this time. Thank you for your continued efforts!

Do you think it would make sense to have a collection of CIs of large 
projects running daily on latest cygwin? If several of these break after 
a release of cygwin, this would give you an early warning that things 
might not be in good shape. I usually don't suspect cygwin if my CI 
breaks, so it usually takes me quite a while to figure this out. But if 
several projects break, this is more obvious and faster to analyze and 
to fix.

Thanks & best regards,

Michael



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