[ https://issues.apache.org/jira/browse/HDFS-767?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
dhruba borthakur updated HDFS-767: ---------------------------------- Resolution: Fixed Fix Version/s: 0.22.0 Hadoop Flags: [Reviewed] Status: Resolved (was: Patch Available) I just committed this. Thanks Ning! > Job failure due to BlockMissingException > ---------------------------------------- > > Key: HDFS-767 > URL: https://issues.apache.org/jira/browse/HDFS-767 > Project: Hadoop HDFS > Issue Type: Improvement > Reporter: Ning Zhang > Assignee: Ning Zhang > Fix For: 0.22.0 > > Attachments: HDFS-767.patch, HDFS-767_2.patch, HDFS-767_3.patch, > HDFS-767_4.txt > > > If a block is request by too many mappers/reducers (say, 3000) at the same > time, a BlockMissingException is thrown because it exceeds the upper limit (I > think 256 by default) of number of threads accessing the same block at the > same time. The DFSClient wil catch that exception and retry 3 times after > waiting for 3 seconds. Since the wait time is a fixed value, a lot of clients > will retry at about the same time and a large portion of them get another > failure. After 3 retries, there are about 256*4 = 1024 clients got the block. > If the number of clients are more than that, the job will fail. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.