[HADOOP-1263] retry logic when dfs exist or open fails temporarily, e.g because of timeout

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.12.3
• Fix Version/s: 0.13.0
• Assignee: Hairong Kuang
• Reporter: Christian Kunz
• Created: 17/Apr/07 05:27
• Updated: 08/Jul/09 16:42
• Resolved: 07/May/07 19:43

Description

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)