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Gopal V commented on TEZ-2358: ------------------------------ [~rajesh.balamohan]: I have more logs for this issue, but they are too big to attach. > Fix MergeManager assumptions about 1 merge per source-task > ---------------------------------------------------------- > > Key: TEZ-2358 > URL: https://issues.apache.org/jira/browse/TEZ-2358 > Project: Apache Tez > Issue Type: Bug > Affects Versions: 0.7.0 > Reporter: Gopal V > Assignee: Rajesh Balamohan > Attachments: > syslog_attempt_1429683757595_0141_1_01_000143_0.syslog.bz2 > > > The Tez MergeManager code assumes that the src-task-id is unique between > merge operations, this results in some confusion when two merge sequences > have to process output from the same src-task-id. > {code} > private TezRawKeyValueIterator finalMerge(Configuration job, FileSystem fs, > List<MapOutput> inMemoryMapOutputs, > List<FileChunk> onDiskMapOutputs > ... > if (inMemoryMapOutputs.size() > 0) { > int srcTaskId = > inMemoryMapOutputs.get(0).getAttemptIdentifier().getInputIdentifier().getInputIndex(); > ... > // must spill to disk, but can't retain in-mem for intermediate merge > final Path outputPath = > mapOutputFile.getInputFileForWrite(srcTaskId, > inMemToDiskBytes).suffix( > > Constants.MERGED_OUTPUT_PREFIX); > ... > {code} > This or some scenario related to this, results in the following FileChunks > list which contains identical named paths with different lengths. > {code} > 2015-04-23 03:28:50,983 INFO [MemtoDiskMerger [Map_1]] > orderedgrouped.MergeManager: Initiating in-memory merge with 6 segments... > 2015-04-23 03:28:50,987 INFO [MemtoDiskMerger [Map_1]] impl.TezMerger: > Merging 6 sorted segments > 2015-04-23 03:28:50,988 INFO [MemtoDiskMerger [Map_1]] impl.TezMerger: Down > to the last merge-pass, with 6 segments left of total size: 1165944755 bytes > 2015-04-23 03:28:58,495 INFO [MemtoDiskMerger [Map_1]] > orderedgrouped.MergeManager: attempt_1429683757595_0141_1_01_000143_0_10027 > Merge of the 6 files in-memory complete. Local file is > /grid/5/cluster/yarn/local/usercache/gopal/appcache/application_1429683757595_0141/attempt_1429683757595_0141_1_01_000143_0_10027_spill_404.out.merged > of size 785583965 > 2015-04-23 03:28:58,496 INFO [ShuffleAndMergeRunner [Map_1]] > orderedgrouped.MergeManager: finalMerge called with 0 in-memory map-outputs > and 5 on-disk map-outputs > 2015-04-23 03:28:58,496 INFO [ShuffleAndMergeRunner [Map_1]] > orderedgrouped.MergeManager: GOPAL: onDiskBytes = 365232290 += > 365232290for/grid/4/cluster/yarn/local/usercache/gopal/appcache/application_1429683757595_0141/attempt_1429683757595_0141_1_01_000143_0_10027_spill_1023.out > 2015-04-23 03:28:58,496 INFO [ShuffleAndMergeRunner [Map_1]] > orderedgrouped.MergeManager: GOPAL: onDiskBytes = 730529899 += > 365297609for/grid/5/cluster/yarn/local/usercache/gopal/appcache/application_1429683757595_0141/attempt_1429683757595_0141_1_01_000143_0_10027_spill_404.out > 2015-04-23 03:28:58,496 INFO [ShuffleAndMergeRunner [Map_1]] > orderedgrouped.MergeManager: GOPAL: onDiskBytes = 1095828683 += > 365298784for/grid/5/cluster/yarn/local/usercache/gopal/appcache/application_1429683757595_0141/attempt_1429683757595_0141_1_01_000143_0_10027_spill_404.out > {code} > The multiple instances of 404.out indicates that we pulled two pipelined > chunks of the same shuffle src id, once into memory and twice onto disk. > {code} > 2015-04-23 03:28:08,256 INFO > [TezTaskEventRouter[attempt_1429683757595_0141_1_01_000143_0]] > orderedgrouped.ShuffleInputEventHandlerOrderedGrouped: DME srcIdx: 143, > targetIdx: 404, attemptNum: 0, payload: [hasEmptyPartitions: true, host: > cn047-10.l42scl.hortonworks.com, port: 13562, pathComponent: > attempt_1429683757595_0141_1_00_000404_0_10009_0, runDuration: 0] > 2015-04-23 03:28:08,270 INFO > [TezTaskEventRouter[attempt_1429683757595_0141_1_01_000143_0]] > orderedgrouped.ShuffleInputEventHandlerOrderedGrouped: DME srcIdx: 143, > targetIdx: 404, attemptNum: 0, payload: [hasEmptyPartitions: true, host: > cn047-10.l42scl.hortonworks.com, port: 13562, pathComponent: > attempt_1429683757595_0141_1_00_000404_0_10009_1, runDuration: 0] > 2015-04-23 03:28:08,272 INFO > [TezTaskEventRouter[attempt_1429683757595_0141_1_01_000143_0]] > orderedgrouped.ShuffleInputEventHandlerOrderedGrouped: DME srcIdx: 143, > targetIdx: 404, attemptNum: 0, payload: [hasEmptyPartitions: true, host: > cn047-10.l42scl.hortonworks.com, port: 13562, pathComponent: > attempt_1429683757595_0141_1_00_000404_0_10009_2, runDuration: 0] > {code} > This will fail depending on how many times _404_0 is at the top of the > FileChunks list in this run. -- This message was sent by Atlassian JIRA (v6.3.4#6332)