[Buildbot-devel] SVN mode copy failed

[Brian Warner]

> >But I get "program finished with exit code -1" in the waterfall. (I
> >don't provide the whole report, nothing else is revelant) in twisted
> >log
> 
> I have been seeing intermittent failures similar to this recently,
> only on 64bit Linux slaves.  It seems to happen less than 10% of the
> time (eyeball figure).  If I rebuild, it typically works.  Are you
> seeing this problem for all builds, or just sometimes?

I have seen this more frequently as of late, and I believe that it has to do
with the use of a PTY on the buildslave. Try adding --usepty=0 when you
create the buildslave (or edit the slave's buildbot.tac file to change the
'usepty = 1' line to read 'usepty = 0').

The buildbot closes stdin of the child process after writes any data that
needs to be written to stdin (such as the body of a patch that needs to be
applied). Very few steps actually use data on stdin, so usually the pipe gets
closed right after process startup. If a PTY is in use, this may cause the
child process to receive a SIGHUP shortly after startup (but after a random
delay influenced by the kernel scheduler). Many programs don't catch SIGHUP
and it causes them to quit. If the SIGHUP arrives late, the program may be
finished already and it isn't a problem. I suspect that something about
recent linux kernels or some change in glibc has increased the frequency of
these sorts of failures.

At least, that's my hunch.. I haven't really been able to prove it. I've
fussed a bit with not closing stdin, but I don't remember being satisfied
with the results. I believe that after setting usepty=0 in my own
buildslaves, the problem went away. I'm considering making usepty=0 the
default for the next release.

hope that helps,
 -Brian