Comment 5 for bug 509015

> Yep this sound about correct.
> Though it should not happen as, there is a _delay_start method which
> waits for the furl files to be created on disk, which should be the test
> that ipcontroller is up and running.

Yes, even though that method exists, we have sometimes observed it to fail.

> Toby, which OS are you on? could the filesystem semantics be different?
> (In theory, it should work on windows/cygwin but I have never tested it)

The problems we had with this were on Windows.

> I have not been able to replicate this so far on NAS backed cluster.
> If this continues to be an issue for you, I can try to give you a patch
> to insert a delay in the ssh engine start.
>
> Regards,
> -vishal
>
> --
> ipcluster does not start all the engines
> https://bugs.launchpad.net/bugs/509015
> You received this bug notification because you are a member of IPython
> Developers, which is subscribed to IPython.
>
> Status in IPython - Enhanced Interactive Python: New
>
> Bug description:
> As reported on the mailing list...
>
>
> ---------- Forwarded message ----------
> From: Toby Burnett <tburnett@EMAIL-REMOVED>
> Date: Sat, Jan 16, 2010 at 8:58 AM
> Subject: [IPython-user] ipcluster does not start all the engines
> To: "<email address hidden>" <email address hidden>
>
>
> Hi,
> I did not find any previous notes on this.
> I have a cluster of 4 machines, each with 8 hyperthreaded cores, so I can run 16 engines per machine, or 64 in all. It is amazingly easy and useful, thanks so much for providing this.
>
> However, when using ipcluster on one of these machines in ssh mode, with this clusterfile,
> send_furl = False
> engines = { 'tev1' : 16,
>           'tev2' : 16,
>           'tev3' : 16,
>           'tev4' : 16
> }
>
> I typically get about 50 engines to actually start. Since there seems to be no log file for ipcluster (in spite of code that seems like it should record which engines it tried to start), I can't send that. The ipcontroller log file looks fine, except for recording fewer than the 64 engines that I expected.
>
> I have an alternative, very klugy method that starts a controller, then executes 64 ssh commands to the respective machines to simply run ipengine. I found the same problem, which went away when I introduced a 1 second delay after each ssh call, which of course takes more than a minute to run, and leaves all those ssh processes running.
>
> So I suspect that the same thing would work in the loop in this method of ipcluster.SSHEngineSet
>
>   def _ssh_engine(self, hostname, count):
>       exec_engine = "ssh %s sh %s/%s-sshx.sh %s" % (
>           hostname, self.temp_dir,
>           os.environ['USER'], self.engine_command
>       )
>       cmds = exec_engine.split()
>       dlist = []
>       log.msg("about to start engines...")
>       for i in range(count):
>           log.msg('Starting engines: %s' % exec_engine)
>           d = getProcessOutput(cmds[0], cmds[1:], env=os.environ)
>           dlist.append(d)
>       return gatherBoth(dlist, consumeErrors=True)
>
> but that would be inelegant, given that the real problem is probably related to the controller not responding properly to multiple requests.
>
> Thanks for looking at this.
>
> --Toby Burnett
>
>
>

--
Brian E. Granger, Ph.D.
Assistant Professor of Physics
Cal Poly State University, San Luis Obispo
<email address hidden>
<email address hidden>