Dstream "Window" uses "union" to combine multiple RDDs in one window into a single RDD. On Tue, Nov 1, 2016 at 2:59 AM kant kodali <kanth...@gmail.com> wrote:
> @Sean It looks like this problem can happen with other RDD's as well. Not > just unionRDD > > On Tue, Nov 1, 2016 at 2:52 AM, kant kodali <kanth...@gmail.com> wrote: > > Hi Sean, > > The comments seem very relevant although I am not sure if this pull > request https://github.com/apache/spark/pull/14985 would fix my issue? I > am not sure what unionRDD.scala has anything to do with my error (I don't > know much about spark code base). Do I ever use unionRDD.scala when I call > mapToPair or ReduceByKey or forEachRDD? This error is very easy to > reproduce you actually don't need to ingest any data to spark streaming > job. Just have one simple transformation consists of mapToPair, reduceByKey > and forEachRDD and have the window interval of 1min and batch interval of > one one second and simple call ssc.awaitTermination() and watch the > Thread Count go up significantly. > > I do think that using a fixed size executor service would probably be a > safer approach. One could leverage ForJoinPool if they think they could > benefit a lot from the work-steal algorithm and doubly ended queues in the > ForkJoinPool. > > Thanks! > > > > > On Tue, Nov 1, 2016 at 2:19 AM, Sean Owen <so...@cloudera.com> wrote: > > Possibly https://issues.apache.org/jira/browse/SPARK-17396 ? > > On Tue, Nov 1, 2016 at 2:11 AM kant kodali <kanth...@gmail.com> wrote: > > Hi Ryan, > > I think you are right. This may not be related to the Receiver. I have > attached jstack dump here. I do a simple MapToPair and reduceByKey and I > have a window Interval of 1 minute (60000ms) and batch interval of 1s ( > 1000) This is generating lot of threads atleast 5 to 8 threads per second > and the total number of threads is monotonically increasing. So just for > tweaking purpose I changed my window interval to 1min (60000ms) and batch > interval of 10s (10000) this looked lot better but still not ideal at > very least it is not monotonic anymore (It goes up and down). Now my > question really is how do I tune such that my number of threads are > optimal while satisfying the window Interval of 1 minute (60000ms) and > batch interval of 1s (1000) ? > > This jstack dump is taken after running my spark driver program for 2 mins > and there are about 1000 threads. > > Thanks! > > > >
