[Swift-devel] Coaster Task Submission Stalling

[Tim Armstrong]

Should be here:

http://people.cs.uchicago.edu/~tga/worker-logs2.tar.gz




On Thu, Sep 4, 2014 at 3:03 PM, Mihael Hategan <hategan at mcs.anl.gov> wrote:

> 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
> > >> > >
> > >> > >
> > >> > >
> > >>
> > >>
> > >>
> > >
>
>
>
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