[
https://issues.apache.org/jira/browse/HADOOP-3604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12607764#action_12607764
]
Doug Cutting commented on HADOOP-3604:
--------------------------------------
> The streaming tasks don't timeout since mapred.task.timeout is set to
> infinity...
That's a bug. Fixing that should be the blocker, no? We should not be forced
to support such a configuration.
Arguably we should have two timeouts, one for user code and one for system
code. If user code hangs, and the user has set an infinite timeout, then the
job will hang and that is not a bug. But if system code hangs then the task
would timeout no matter what the user timeout setting. In general, however,
that would be hard to implement, since user code can call system code and vice
versa. But in this particular case, during the shuffle, there's no user code
running (except comparators when merging) so we could in theory somehow reset
the task timeout during copies. But even that may be difficult, if some
threads are copying and some are merging. Sigh. I think we're better of just
saying that setting an infinite timeout risks jobs hanging, that Hadoop cannot,
e.g., guarantee that jvm's don't ever hang.
> Reduce stuck at shuffling phase
> -------------------------------
>
> Key: HADOOP-3604
> URL: https://issues.apache.org/jira/browse/HADOOP-3604
> Project: Hadoop Core
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.18.0
> Reporter: Runping Qi
> Assignee: Arun C Murthy
> Priority: Blocker
> Fix For: 0.18.0
>
> Attachments: HADOOP-3604_0_20080623.patch, stack.txt
>
>
> I was running gridmix with Hadoop 0.18.
> I set the map output compression to true.
> Most of the jobs completed just fine.
> Three jobs, however, got stuck.
> Each has one reducer stuck at shuffling phase.
> Here is the log:
> 2008-06-20 00:06:01,264 INFO org.apache.hadoop.metrics.jvm.JvmMetrics:
> Initializing JVM Metrics with processName=SHUFFLE, sessionId=
> 2008-06-20 00:06:01,415 INFO org.apache.hadoop.streaming.PipeMapRed:
> PipeMapRed exec [/bin/cat]
> 2008-06-20 00:06:01,463 INFO org.apache.hadoop.mapred.ReduceTask:
> ShuffleRamManager: MemoryLimit=134217728, MaxSingleShuffleLimit=33554432
> 2008-06-20 00:06:01,474 INFO org.apache.hadoop.util.NativeCodeLoader: Loaded
> the native-hadoop library
> 2008-06-20 00:06:01,475 INFO org.apache.hadoop.io.compress.zlib.ZlibFactory:
> Successfully loaded & initialized native-zlib library
> 2008-06-20 00:06:01,476 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,477 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,477 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,478 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,478 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,486 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,486 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,487 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,487 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,488 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,488 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,489 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,489 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,489 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,493 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,496 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,496 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,496 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,497 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,497 INFO org.apache.hadoop.io.compress.CodecPool: Got
> brand-new decompressor
> 2008-06-20 00:06:01,500 INFO org.apache.hadoop.mapred.ReduceTask:
> attempt_200806192318_0450_r_000016_0 Thread started: Thread for merging
> on-disk files
> 2008-06-20 00:06:01,500 INFO org.apache.hadoop.mapred.ReduceTask:
> attempt_200806192318_0450_r_000016_0 Thread waiting: Thread for merging
> on-disk files
> 2008-06-20 00:06:01,502 INFO org.apache.hadoop.mapred.ReduceTask:
> attempt_200806192318_0450_r_000016_0 Need another 270 map output(s) where 0
> is already in progress
> 2008-06-20 00:06:01,503 INFO org.apache.hadoop.mapred.ReduceTask:
> attempt_200806192318_0450_r_000016_0 Thread started: Thread for merging in
> memory files
> 2008-06-20 00:06:01,503 INFO org.apache.hadoop.mapred.ReduceTask:
> attempt_200806192318_0450_r_000016_0: Got 0 new map-outputs & number of known
> map outputs is 0
> 2008-06-20 00:06:01,504 INFO org.apache.hadoop.mapred.ReduceTask:
> attempt_200806192318_0450_r_000016_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-06-20 00:06:06,654 INFO org.apache.hadoop.mapred.ReduceTask:
> attempt_200806192318_0450_r_000016_0: Got 269 new map-outputs & number of
> known map outputs is 269
> 2008-06-20 00:06:06,656 INFO org.apache.hadoop.mapred.ReduceTask:
> attempt_200806192318_0450_r_000016_0 Scheduled 229 of 269 known outputs (0
> slow hosts and 40 dup hosts)
> 2008-06-20 00:06:07,163 INFO org.apache.hadoop.mapred.ReduceTask: Shuffling
> 846183 bytes (210104 raw bytes) into RAM-FS from
> attempt_200806192318_0450_m_000089_0
> 2008-06-20 00:06:07,163 INFO org.apache.hadoop.mapred.ReduceTask: Shuffling
> 820890 bytes (204371 raw bytes) into RAM-FS from
> attempt_200806192318_0450_m_000083_0
> 2008-06-20 00:06:07,166 INFO org.apache.hadoop.mapred.ReduceTask: Shuffling
> 835672 bytes (208085 raw bytes) into RAM-FS from
> attempt_200806192318_0450_m_000122_0
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
