stacktrace? details? On Mon, Jan 18, 2016 at 5:58 AM, Mennour Rostom <mennou...@gmail.com> wrote:
> Hi, > > I am running my app in a single machine first before moving it in the > cluster; actually simultaneous actions are not working for me now; is this > comming from the fact that I am using a single machine ? yet I am using > FAIR scheduler. > > 2016-01-17 21:23 GMT+01:00 Mark Hamstra <m...@clearstorydata.com>: > >> It can be far more than that (e.g. >> https://issues.apache.org/jira/browse/SPARK-11838), and is generally >> either unrecognized or a greatly under-appreciated and underused feature of >> Spark. >> >> On Sun, Jan 17, 2016 at 12:20 PM, Koert Kuipers <ko...@tresata.com> >> wrote: >> >>> the re-use of shuffle files is always a nice surprise to me >>> >>> On Sun, Jan 17, 2016 at 3:17 PM, Mark Hamstra <m...@clearstorydata.com> >>> wrote: >>> >>>> Same SparkContext means same pool of Workers. It's up to the >>>> Scheduler, not the SparkContext, whether the exact same Workers or >>>> Executors will be used to calculate simultaneous actions against the same >>>> RDD. It is likely that many of the same Workers and Executors will be used >>>> as the Scheduler tries to preserve data locality, but that is not >>>> guaranteed. In fact, what is most likely to happen is that the shared >>>> Stages and Tasks being calculated for the simultaneous actions will not >>>> actually be run at exactly the same time, which means that shuffle files >>>> produced for one action will be reused by the other(s), and repeated >>>> calculations will be avoided even without explicitly caching/persisting the >>>> RDD. >>>> >>>> On Sun, Jan 17, 2016 at 8:06 AM, Koert Kuipers <ko...@tresata.com> >>>> wrote: >>>> >>>>> Same rdd means same sparkcontext means same workers >>>>> >>>>> Cache/persist the rdd to avoid repeated jobs >>>>> On Jan 17, 2016 5:21 AM, "Mennour Rostom" <mennou...@gmail.com> wrote: >>>>> >>>>>> Hi, >>>>>> >>>>>> Thank you all for your answers, >>>>>> >>>>>> If I correctly understand, actions (in my case foreach) can be run >>>>>> concurrently and simultaneously on the SAME rdd, (which is logical >>>>>> because >>>>>> they are read only object). however, I want to know if the same workers >>>>>> are >>>>>> used for the concurrent analysis ? >>>>>> >>>>>> Thank you >>>>>> >>>>>> 2016-01-15 21:11 GMT+01:00 Jakob Odersky <joder...@gmail.com>: >>>>>> >>>>>>> I stand corrected. How considerable are the benefits though? Will >>>>>>> the scheduler be able to dispatch jobs from both actions simultaneously >>>>>>> (or >>>>>>> on a when-workers-become-available basis)? >>>>>>> >>>>>>> On 15 January 2016 at 11:44, Koert Kuipers <ko...@tresata.com> >>>>>>> wrote: >>>>>>> >>>>>>>> we run multiple actions on the same (cached) rdd all the time, i >>>>>>>> guess in different threads indeed (its in akka) >>>>>>>> >>>>>>>> On Fri, Jan 15, 2016 at 2:40 PM, Matei Zaharia < >>>>>>>> matei.zaha...@gmail.com> wrote: >>>>>>>> >>>>>>>>> RDDs actually are thread-safe, and quite a few applications use >>>>>>>>> them this way, e.g. the JDBC server. >>>>>>>>> >>>>>>>>> Matei >>>>>>>>> >>>>>>>>> On Jan 15, 2016, at 2:10 PM, Jakob Odersky <joder...@gmail.com> >>>>>>>>> wrote: >>>>>>>>> >>>>>>>>> I don't think RDDs are threadsafe. >>>>>>>>> More fundamentally however, why would you want to run RDD actions >>>>>>>>> in parallel? The idea behind RDDs is to provide you with an >>>>>>>>> abstraction for >>>>>>>>> computing parallel operations on distributed data. Even if you were >>>>>>>>> to call >>>>>>>>> actions from several threads at once, the individual executors of your >>>>>>>>> spark environment would still have to perform operations sequentially. >>>>>>>>> >>>>>>>>> As an alternative, I would suggest to restructure your RDD >>>>>>>>> transformations to compute the required results in one single >>>>>>>>> operation. >>>>>>>>> >>>>>>>>> On 15 January 2016 at 06:18, Jonathan Coveney <jcove...@gmail.com> >>>>>>>>> wrote: >>>>>>>>> >>>>>>>>>> Threads >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> El viernes, 15 de enero de 2016, Kira <mennou...@gmail.com> >>>>>>>>>> escribió: >>>>>>>>>> >>>>>>>>>>> Hi, >>>>>>>>>>> >>>>>>>>>>> Can we run *simultaneous* actions on the *same RDD* ?; if yes >>>>>>>>>>> how can this >>>>>>>>>>> be done ? >>>>>>>>>>> >>>>>>>>>>> Thank you, >>>>>>>>>>> Regards >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> -- >>>>>>>>>>> View this message in context: >>>>>>>>>>> http://apache-spark-user-list.1001560.n3.nabble.com/simultaneous-actions-tp25977.html >>>>>>>>>>> Sent from the Apache Spark User List mailing list archive at >>>>>>>>>>> Nabble.com <http://nabble.com>. >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> --------------------------------------------------------------------- >>>>>>>>>>> To unsubscribe, e-mail: user-unsubscr...@spark.apache.org >>>>>>>>>>> For additional commands, e-mail: user-h...@spark.apache.org >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>> >>>>>> >>>> >>> >> >
