hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Hairong Kuang (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-1263) retry logic when dfs exist or open fails temporarily, e.g because of timeout
Date Wed, 25 Apr 2007 23:33:15 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-1263?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12491839
] 

Hairong Kuang commented on HADOOP-1263:
---------------------------------------

The annotation method proposed in HADOOP-601 to provide a general retry framework in rpc seems
to be a simple solution, but since it is not implemented, for this jira, I plan to implement
the retry mechanism for only ClientProtocol using the retry framework implemented in HADOOP-997.
Here are what I plan to do:

1. Add an exponential backoff policy to RetryPolicies.
2. Create a retry proxy for the dfs client using the following method-to-RetryPolicy hashmap:
     * TRY-ONCE-THEN-FAIL: create, addBlock, complete 
     * EXPONENTIAL-BACKOFF: open, setReplication, abandonBlock, abandonFileInProgress,  reportBadBlocks,
exists, isDir, getListing, getHints,  renewLease, getStats, getDatanodeReport, getBlockSize,
getEditLogSize
     * I still have not decided which retry policy to use for
         (1)  rename, delete, mkdirs because a retry following a successful operation at the
server side will return false instead of true;
         (2)  setSafeMode, refreshNodes, rollEditLog, rollFsImage, finalizeUpgrade, metaSave
because I still need time to read the code for these methods.

Any suggestion is welcome!

> retry logic when dfs exist or open fails temporarily, e.g because of timeout
> ----------------------------------------------------------------------------
>
>                 Key: HADOOP-1263
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1263
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: dfs
>    Affects Versions: 0.12.3
>            Reporter: Christian Kunz
>         Assigned To: Hairong Kuang
>
> Sometimes, when many (e.g. 1000+) map jobs start at about the same time and require supporting
files from filecache, it happens that some map tasks fail because of rpc timeouts. With only
the default number of 10 handlers on the namenode, the probability is high that the whole
job fails (see Hadoop-1182). It is much better with a higher number of handlers, but some
map tasks still fail.
> This could be avoided if rpc clients did retry when encountering a timeout before throwing
an exception.
> Examples of exceptions:
> java.net.SocketTimeoutException: timed out waiting for rpc response
> at org.apache.hadoop.ipc.Client.call(Client.java:473)
> at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:163)
> at org.apache.hadoop.dfs.$Proxy1.exists(Unknown Source)
> at org.apache.hadoop.dfs.DFSClient.exists(DFSClient.java:320)
> at org.apache.hadoop.dfs.DistributedFileSystem$RawDistributedFileSystem.exists(DistributedFileSystem.java:170)
> at org.apache.hadoop.dfs.DistributedFileSystem$RawDistributedFileSystem.open(DistributedFileSystem.java:125)
> at org.apache.hadoop.fs.ChecksumFileSystem$FSInputChecker.(ChecksumFileSystem.java:110)
> at org.apache.hadoop.fs.ChecksumFileSystem.open(ChecksumFileSystem.java:330)
> at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:245)
> at org.apache.hadoop.filecache.DistributedCache.createMD5(DistributedCache.java:327)
> at org.apache.hadoop.filecache.DistributedCache.ifExistsAndFresh(DistributedCache.java:253)
> at org.apache.hadoop.filecache.DistributedCache.localizeCache(DistributedCache.java:169)
> at org.apache.hadoop.filecache.DistributedCache.getLocalCache(DistributedCache.java:86)
> at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:117)
> java.net.SocketTimeoutException: timed out waiting for rpc response
>         at org.apache.hadoop.ipc.Client.call(Client.java:473)
>         at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:163)
>         at org.apache.hadoop.dfs.$Proxy1.open(Unknown Source)
>         at org.apache.hadoop.dfs.DFSClient$DFSInputStream.openInfo(DFSClient.java:511)
>         at org.apache.hadoop.dfs.DFSClient$DFSInputStream.<init>(DFSClient.java:498)
>         at org.apache.hadoop.dfs.DFSClient.open(DFSClient.java:207)
>         at org.apache.hadoop.dfs.DistributedFileSystem$RawDistributedFileSystem.open(DistributedFileSystem.java:129)
>         at org.apache.hadoop.fs.ChecksumFileSystem$FSInputChecker.<init>(ChecksumFileSystem.java:110)
>         at org.apache.hadoop.fs.ChecksumFileSystem.open(ChecksumFileSystem.java:330)
>         at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:245)
>         at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:82)
>         at org.apache.hadoop.fs.ChecksumFileSystem.copyToLocalFile(ChecksumFileSystem.java:577)
>         at org.apache.hadoop.fs.FileSystem.copyToLocalFile(FileSystem.java:766)
>         at org.apache.hadoop.mapred.TaskTracker.localizeJob(TaskTracker.java:370)
>         at org.apache.hadoop.mapred.TaskTracker.startNewTask(TaskTracker.java:877)
>         at org.apache.hadoop.mapred.TaskTracker.offerService(TaskTracker.java:545)
>         at org.apache.hadoop.mapred.TaskTracker.run(TaskTracker.java:913)
>         at org.apache.hadoop.mapred.TaskTracker.main(TaskTracker.java:1603)

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message