[MLton] Slow commits to MLton's SVN repository

[Matthew Fluet]

>> For the second time I encountered difficulty performing a largish (but 
>> not
>> that large) commit to MLton's SVN repository.  Looking at ps output, the
>> commit ran for at least about 40 minutes before I decided to give up and
>> perform multiple small commits instead.  What could be the problem?  
>> Is the
>> SVN server very old?  Are precommit scripts taking ages?
> 
> I'm running into this as well, trying to commit the merge of some trunk 
> revisions into the x86_64 branch (which I do not want to split into 
> separate commits).
> 
> It's definitely some sort of problem with the pre-commit scripts. 

There was a 'set -x' in the 'pre-commit' script; this seems to have 
flooded stdout in a way that wedged the processes.  (Presumably the 
process that launches 'pre-commit' doesn't connect stdout to a consumer, 
so things get stuck if 'pre-commit' generates more than a single pipe 
buffer's worth of data.)

Should have seen that immediately from the strace showing the pre-commit 
blocked on write.

In any case, removing the 'set -x' let my commit go through, in under 
two minutes.