Anyway it would be good if someone from the Mesos side investigates this and proposes a solution. The 32 MB per task hack isn't completely foolproof either (e.g. people might allocate all the RAM to their executor and thus stop being able to launch tasks), so maybe we wait on a Mesos fix for this one.
Matei On August 25, 2014 at 1:07:15 PM, Matei Zaharia (matei.zaha...@gmail.com) wrote: This is kind of weird then, seems perhaps unrelated to this issue (or at least to the way I understood it). Is the problem maybe that Mesos saw 0 MB being freed and didn't re-offer the machine *even though there was more than 32 MB free overall*? Matei On August 25, 2014 at 12:59:59 PM, Cody Koeninger (c...@koeninger.org) wrote: I definitely saw a case where a. the only job running was a 256m shell b. I started a 2g job c. a little while later the same user as in a started another 256m shell My job immediately stopped making progress. Once user a killed his shells, it started again. This is on nodes with ~15G of memory, on which we have successfully run 8G jobs. On Mon, Aug 25, 2014 at 2:02 PM, Matei Zaharia <matei.zaha...@gmail.com> wrote: BTW it seems to me that even without that patch, you should be getting tasks launched as long as you leave at least 32 MB of memory free on each machine (that is, the sum of the executor memory sizes is not exactly the same as the total size of the machine). Then Mesos will be able to re-offer that machine whenever CPUs free up. Matei On August 25, 2014 at 5:05:56 AM, Gary Malouf (malouf.g...@gmail.com) wrote: We have not tried the work-around because there are other bugs in there that affected our set-up, though it seems it would help. On Mon, Aug 25, 2014 at 12:54 AM, Timothy Chen <tnac...@gmail.com> wrote: > +1 to have the work around in. > > I'll be investigating from the Mesos side too. > > Tim > > On Sun, Aug 24, 2014 at 9:52 PM, Matei Zaharia <matei.zaha...@gmail.com> > wrote: > > Yeah, Mesos in coarse-grained mode probably wouldn't work here. It's too > bad that this happens in fine-grained mode -- would be really good to fix. > I'll see if we can get the workaround in > https://github.com/apache/spark/pull/1860 into Spark 1.1. Incidentally > have you tried that? > > > > Matei > > > > On August 23, 2014 at 4:30:27 PM, Gary Malouf (malouf.g...@gmail.com) > wrote: > > > > Hi Matei, > > > > We have an analytics team that uses the cluster on a daily basis. They > use two types of 'run modes': > > > > 1) For running actual queries, they set the spark.executor.memory to > something between 4 and 8GB of RAM/worker. > > > > 2) A shell that takes a minimal amount of memory on workers (128MB) for > prototyping out a larger query. This allows them to not take up RAM on the > cluster when they do not really need it. > > > > We see the deadlocks when there are a few shells in either case. From > the usage patterns we have, coarse-grained mode would be a challenge as we > have to constantly remind people to kill their shells as soon as their > queries finish. > > > > Am I correct in viewing Mesos in coarse-grained mode as being similar to > Spark Standalone's cpu allocation behavior? > > > > > > > > > > On Sat, Aug 23, 2014 at 7:16 PM, Matei Zaharia <matei.zaha...@gmail.com> > wrote: > > Hey Gary, just as a workaround, note that you can use Mesos in > coarse-grained mode by setting spark.mesos.coarse=true. Then it will hold > onto CPUs for the duration of the job. > > > > Matei > > > > On August 23, 2014 at 7:57:30 AM, Gary Malouf (malouf.g...@gmail.com) > wrote: > > > > I just wanted to bring up a significant Mesos/Spark issue that makes the > > combo difficult to use for teams larger than 4-5 people. It's covered in > > https://issues.apache.org/jira/browse/MESOS-1688. My understanding is > that > > Spark's use of executors in fine-grained mode is a very different > behavior > > than many of the other common frameworks for Mesos. > > >
