[Gluster-devel] Problems with ec/nfs.t in regression tests

[Shyam]

On 02/11/2015 09:40 AM, Xavier Hernandez wrote:
> Hi,
>
> it seems that there are some failures in ec/nfs.t test on regression
> tests. Doing some investigation I've found that before applying the
> multi-threaded patch (commit 5e25569e) the problem does not seem to happen.

This has in interesting history in failures, on the regression runs for 
the MT epoll this (i.e ec/nfs.t) did not fail (there were others, but 
not nfs.t).

The patch that allows configuration of MT epoll is where this started 
failing around Feb 5th (but later passed). (see patchset 7 failures on, 
http://review.gluster.org/#/c/9488/ )

I state the above, as it may help narrowing down the changes in EC 
(maybe) that could have caused it.

Also in the latter commit, there was an error configuring the number of 
threads so all regression runs would have run with a single epoll thread 
(the MT epoll patch had this hard coded, so that would have run with 2 
threads, but did not show up the issue (patch: 
http://review.gluster.org/#/c/3842/)).

Again I state the above, as this should not be exposing a 
race/bug/problem due to the multi threaded nature of epoll, but of 
course needs investigation.

>
> I'm not sure if this patch is the cause or it has revealed some bug in
> ec or any other xlator.

I guess we can reproduce this issue? If so I would try setting 
client.event-threads on master branch to 1, restarting the volume and 
then running the test (as a part of the test itself maybe) to eliminate 
the possibility that MT epoll is causing it.

My belief on MT epoll causing it is in doubt as the runs failed on the 
http://review.gluster.org/#/c/9488/ (configuration patch), which had the 
thread count as 1 due to a bug in that code.

>
> I can try to identify it (any help will be appreciated), but it may take
> some time. Would it be better to remove the test in the meantime ?

I am checking if this is reproducible on my machine, so that I can 
possibly see what is going wrong.

Shyam