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Allen Wittenauer resolved HDFS-232. ----------------------------------- Resolution: Won't Fix Given X-trace was dead a year or so after this Jira was filed, I'm closing this as won't fix. > Cross-system causal tracing within Hadoop > ----------------------------------------- > > Key: HDFS-232 > URL: https://issues.apache.org/jira/browse/HDFS-232 > Project: Hadoop HDFS > Issue Type: New Feature > Reporter: George Porter > Attachments: HADOOP-4049.2-ipc.patch, HADOOP-4049.3-ipc.patch, > HADOOP-4049.4-rpc.patch, HADOOP-4049.6-rpc.patch, HADOOP-4049.7-rpc.patch, > HADOOP-4049.patch, multiblockread.png, multiblockwrite.png > > > Much of Hadoop's behavior is client-driven, with clients responsible for > contacting individual datanodes to read and write data, as well as dividing > up work for map and reduce tasks. In a large deployment with many concurrent > users, identifying the effects of individual clients on the infrastructure is > a challenge. The use of data pipelining in HDFS and Map/Reduce make it hard > to follow the effects of a given client request through the system. > This proposal is to instrument the HDFS, IPC, and Map/Reduce layers of Hadoop > with X-Trace. X-Trace is an open-source framework for capturing causality of > events in a distributed system. It can correlate operations making up a > single user request, even if those operations span multiple machines. As an > example, you could use X-Trace to follow an HDFS write operation as it is > pipelined through intermediate nodes. Additionally, you could trace a single > Map/Reduce job and see how it is decomposed into lower-layer HDFS operations. > Matei Zaharia and Andy Konwinski initially integrated X-Trace with a local > copy of the 0.14 release, and I've brought that code up to release 0.17. > Performing the integration involves modifying the IPC protocol, > inter-datanode protocol, and some data structures in the map/reduce layer to > include 20-byte long tracing metadata. With release 0.18, the generated > traces could be collected with Chukwa. > I've attached some example traces of HDFS and IPC layers from the 0.17 patch > to this JIRA issue. > More information about X-Trace is available from http://www.x-trace.net/ as > well as in a paper that appeared at NSDI 2007, available online at > http://www.usenix.org/events/nsdi07/tech/fonseca.html -- This message was sent by Atlassian JIRA (v6.2#6252)