Hi, You are right, but in fact it does not solve my problem, since I have 100 parallelism everywhere. Each of my 100 sources gives only a few lines (say 14 max), and only the first 14 next nodes will receive data. Same problem by replacing rebalance() with shuffle().
But I found a workaround: setting parallelism to 1 for the source (I don't need a 100 directory scanners anyway), it forces the rebalancing evenly between the mappers. Greetings, Arnaud -----Message d'origine----- De : Matthias J. Sax [mailto:mj...@apache.org] Envoyé : mercredi 2 septembre 2015 17:56 À : user@flink.apache.org Objet : Re: How to force the parallelism on small streams? Hi, If I understand you correctly, you want to have 100 mappers. Thus you need to apply the .setParallelism() after .map() > addSource(myFileSource).rebalance().map(myFileMapper).setParallelism(1 > 00) The order of commands you used, set the dop for the source to 100 (which might be ignored, if the provided source function "myFileSource" does not implements "ParallelSourceFunction" interface). The dop for the mapper should be the default value. Using .rebalance() is absolutely correct. It distributes the emitted tuples in a round robin fashion to all consumer tasks. -Matthias On 09/02/2015 05:41 PM, LINZ, Arnaud wrote: > Hi, > > > > I have a source that provides few items since it gives file names to > the mappers. The mapper opens the file and process records. As the > files are huge, one input line (a filename) gives a consequent work to the > next stage. > > My topology looks like : > > addSource(myFileSource).rebalance().setParallelism(100).map(myFileMapp > er) > > If 100 mappers are created, about 85 end immediately and only a few > process the files (for hours). I suspect an optimization making that > there is a minimum number of lines to pass to the next node or it is > “shutdown” ; but in my case I do want the lines to be evenly > distributed to each mapper. > > How to enforce that ? > > > > Greetings, > > Arnaud > > > ---------------------------------------------------------------------- > -- > > L'intégrité de ce message n'étant pas assurée sur internet, la société > expéditrice ne peut être tenue responsable de son contenu ni de ses > pièces jointes. Toute utilisation ou diffusion non autorisée est > interdite. Si vous n'êtes pas destinataire de ce message, merci de le > détruire et d'avertir l'expéditeur. > > The integrity of this message cannot be guaranteed on the Internet. > The company that sent this message cannot therefore be held liable for > its content nor attachments. Any unauthorized use or dissemination is > prohibited. If you are not the intended recipient of this message, > then please delete it and notify the sender.
