T3l, Did Sean Owen's suggestion help? If not, can you please share the behaviour?
Cheers. On 20 Oct 2015 11:02 pm, "Lan Jiang" <ljia...@gmail.com> wrote: > I think the data file is binary per the original post. So in this case, > sc.binaryFiles should be used. However, I still recommend against using so > many small binary files as > > 1. They are not good for batch I/O > 2. They put too many memory pressure on namenode. > > Lan > > > On Oct 20, 2015, at 11:20 AM, Deenar Toraskar <deenar.toras...@gmail.com> > wrote: > > also check out wholeTextFiles > > > https://spark.apache.org/docs/1.4.0/api/java/org/apache/spark/SparkContext.html#wholeTextFiles(java.lang.String,%20int) > > On 20 October 2015 at 15:04, Lan Jiang <ljia...@gmail.com> wrote: > >> As Francois pointed out, you are encountering a classic small file >> anti-pattern. One solution I used in the past is to wrap all these small >> binary files into a sequence file or avro file. For example, the avro >> schema can have two fields: filename: string and binaryname:byte[]. Thus >> your file is splittable and will not create so many partitions. >> >> Lan >> >> >> On Oct 20, 2015, at 8:03 AM, François Pelletier < >> newslett...@francoispelletier.org> wrote: >> >> You should aggregate your files in larger chunks before doing anything >> else. HDFS is not fit for small files. It will bloat it and cause you a lot >> of performance issues. Target a few hundred MB chunks partition size and >> then save those files back to hdfs and then delete the original ones. You >> can read, use coalesce and the saveAsXXX on the result. >> >> I had the same kind of problem once and solved it in bunching 100's of >> files together in larger ones. I used text files with bzip2 compression. >> >> >> >> Le 2015-10-20 08:42, Sean Owen a écrit : >> >> coalesce without a shuffle? it shouldn't be an action. It just treats >> many partitions as one. >> >> On Tue, Oct 20, 2015 at 1:00 PM, t3l <t...@threelights.de> wrote: >> >>> >>> I have dataset consisting of 50000 binary files (each between 500kb and >>> 2MB). They are stored in HDFS on a Hadoop cluster. The datanodes of the >>> cluster are also the workers for Spark. I open the files as a RDD using >>> sc.binaryFiles("hdfs:///path_to_directory").When I run the first action >>> that >>> involves this RDD, Spark spawns a RDD with more than 30000 partitions. >>> And >>> this takes ages to process these partitions even if you simply run >>> "count". >>> Performing a "repartition" directly after loading does not help, because >>> Spark seems to insist on materializing the RDD created by binaryFiles >>> first. >>> >>> How I can get around this? >>> >>> >>> >>> -- >>> View this message in context: >>> http://apache-spark-user-list.1001560.n3.nabble.com/Ahhhh-Spark-creates-30000-partitions-What-can-I-do-tp25140.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 >>> >>> >> >> >> > >
