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He Yongqiang commented on MAPREDUCE-2841: ----------------------------------------- sorry, i am kind of confused. i may should make me more clear: we are trying to evaluate and compare the c++ impl in HCE (and also this jira) and doing a pure java re-impl. So the thing that we mostly cared about is that is there sth that the c++ impl can do and a java re-impl can not. And if there is, we need to find out how much is that difference. And from there we can have a better understand of each approach and decide which approach to go. > Task level native optimization > ------------------------------ > > Key: MAPREDUCE-2841 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-2841 > Project: Hadoop Map/Reduce > Issue Type: Improvement > Components: task > Environment: x86-64 Linux > Reporter: Binglin Chang > Assignee: Binglin Chang > Attachments: MAPREDUCE-2841.v1.patch, dualpivot-0.patch, > dualpivotv20-0.patch > > > I'm recently working on native optimization for MapTask based on JNI. > The basic idea is that, add a NativeMapOutputCollector to handle k/v pairs > emitted by mapper, therefore sort, spill, IFile serialization can all be done > in native code, preliminary test(on Xeon E5410, jdk6u24) showed promising > results: > 1. Sort is about 3x-10x as fast as java(only binary string compare is > supported) > 2. IFile serialization speed is about 3x of java, about 500MB/s, if hardware > CRC32C is used, things can get much faster(1G/s). > 3. Merge code is not completed yet, so the test use enough io.sort.mb to > prevent mid-spill > This leads to a total speed up of 2x~3x for the whole MapTask, if > IdentityMapper(mapper does nothing) is used. > There are limitations of course, currently only Text and BytesWritable is > supported, and I have not think through many things right now, such as how to > support map side combine. I had some discussion with somebody familiar with > hive, it seems that these limitations won't be much problem for Hive to > benefit from those optimizations, at least. Advices or discussions about > improving compatibility are most welcome:) > Currently NativeMapOutputCollector has a static method called canEnable(), > which checks if key/value type, comparator type, combiner are all compatible, > then MapTask can choose to enable NativeMapOutputCollector. > This is only a preliminary test, more work need to be done. I expect better > final results, and I believe similar optimization can be adopt to reduce task > and shuffle too. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira