[Swift-devel] Coaster Task Submission Stalling

[Mihael Hategan]

The first worker "failing" is 0904-20022331. The log looks funny at the
end.

Can you git pull and re-run? The worker is getting some command at the
end there and doing nothing about it and I wonder why.

Mihael

On Thu, 2014-09-04 at 14:35 -0500, Tim Armstrong wrote:
> Ok, now I have some worker logs:
> 
> http://people.cs.uchicago.edu/~tga/2014-9-4-worker-logs.tar.gz
> 
> There's nothing obvious I see in the worker logs that would indicate why
> the connection was broken.
> 
> - Tim
> 
> 
> On Thu, Sep 4, 2014 at 1:11 PM, Tim Armstrong <tim.g.armstrong at gmail.com>
> wrote:
> 
> > This is all running locally on my laptop, so I think we can rule out 1).
> >
> > It also seems like it's a state the coaster service gets into after a few
> > client sessions: generally the first coaster run works fine, then after a
> > few runs the problem occurs more frequently.
> >
> > I'm going to try and get worker logs, in the meantime i've got some
> > jstacks (attached).
> >
> > Matching service logs (largish) are here if needed:
> > http://people.cs.uchicago.edu/~tga/service.out.gz
> >
> >
> > On Wed, Sep 3, 2014 at 10:35 PM, Mihael Hategan <hategan at mcs.anl.gov>
> > wrote:
> >
> >> Ah, makes sense.
> >>
> >> 2 minutes is the channel timeout. Each live connection is guaranteed to
> >> have some communication for any 2 minute time window, partially due to
> >> periodic heartbeats (sent every 1 minute). If no packets flow for the
> >> duration of 2 minutes, the connection is assumed broken and all jobs
> >> that were submitted to the respective workers are considered failed. So
> >> there seems to be an issue with the connections to some of the workers,
> >> and it takes 2 minutes to detect them.
> >>
> >> Since the service seems to be alive (although a jstack on the service
> >> when thing seem to hang might help), this leaves two possibilities:
> >> 1 - some genuine network problem
> >> 2 - the worker died without properly closing TCP connections
> >>
> >> If (2), you could enable worker logging
> >> (Settings::Key::WORKER_LOGGING_LEVEL = "DEBUG") to see if anything shows
> >> up.
> >>
> >> Mihael
> >>
> >> On Wed, 2014-09-03 at 20:26 -0500, Tim Armstrong wrote:
> >> > Here are client and service logs, with part of service log edited down
> >> to
> >> > be a reasonable size (I have the full thing if needed, but it was over a
> >> > gigabyte).
> >> >
> >> > One relevant section is from 19:49:35 onwards.  The client submits 4
> >> jobs
> >> > (its limit), but they don't complete until 19:51:32 or so (I can see
> >> that
> >> > one task completed based on ncompleted=1 in the check_tasks log
> >> message).
> >> > It looks like something has happened with broken pipes and workers being
> >> > lost, but I'm not sure what the ultimate cause of that is likely to be.
> >> >
> >> > - Tim
> >> >
> >> >
> >> >
> >> > On Wed, Sep 3, 2014 at 6:20 PM, Mihael Hategan <hategan at mcs.anl.gov>
> >> wrote:
> >> >
> >> > > Hi Tim,
> >> > >
> >> > > I've never seen this before with pure Java.
> >> > >
> >> > > Do you have logs from these runs?
> >> > >
> >> > > Mihael
> >> > >
> >> > > On Wed, 2014-09-03 at 16:49 -0500, Tim Armstrong wrote:
> >> > > > I'm running a test Swift/T script that submit tasks to Coasters
> >> through
> >> > > the
> >> > > > C++ client and I'm seeing some odd behaviour where task
> >> > > > submission/execution is stalling for ~2 minute periods.  For
> >> example, I'm
> >> > > > seeing submit log messages like "submitting
> >> > > > urn:133-1409778135377-1409778135378: /bin/hostname" in bursts of
> >> several
> >> > > > seconds with a gap of roughly 2 minutes in between, e.g. I'm seeing
> >> > > bursts
> >> > > > with the following intervals in my logs.
> >> > > >
> >> > > > 16:07:04,603 to 16:07:10,391
> >> > > > 16:09:07,377 to 16:09:13,076
> >> > > > 16:11:10,005 to 16:11:16,770
> >> > > > 16:13:13,291 to 16:13:19,296
> >> > > > 16:15:16,000 to 16:15:21,602
> >> > > >
> >> > > > From what I can tell, the delay is on the coaster service side: the
> >> C
> >> > > > client is just waiting for a response.
> >> > > >
> >> > > > The jobs are just being submitted through the local job manager, so
> >> I
> >> > > > wouldn't expect any delays there.  The tasks are also just
> >> > > "/bin/hostname",
> >> > > > so should return immediately.
> >> > > >
> >> > > > I'm going to continue digging into this on my own, but the 2 minute
> >> delay
> >> > > > seems like a big clue: does anyone have an idea what could cause
> >> stalls
> >> > > in
> >> > > > task submission of 2 minute duration?
> >> > > >
> >> > > > Cheers,
> >> > > > Tim
> >> > >
> >> > >
> >> > >
> >>
> >>
> >>
> >