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https://issues.apache.org/jira/browse/HDFS-767?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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dhruba borthakur updated HDFS-767:
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Status: Open (was: Patch Available)
Hi Ning, can we get a few more minor issues fixed:
{quote}
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements. See the NOTICE file
+ * Licensed the Apache Software Foundation (ASF) under one
+ * or more contributor license See.
+ * agreements the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
{quote}
The above change change be reverted.
{quote}
prefetchSize =
conf.getLong(DFSConfigKeys.DFS_CLIENT_READ_PREFETCH_SIZE_KEY, prefetchSize);
+ timeWindow =
conf.getInt("dfs.client.baseTimeWindow.waitOn.BlockMissingException", 3000);
{quote}
can we add the new configuration value to DFSConfigKeys?
{quote}
+ // See JIRA HDFS-767 for more details.
{quote}
Remove the above comment because this is already captured in the svn revision
history
Thanks a bunch
> 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
> Attachments: HDFS-767.patch, HDFS-767_2.patch
>
>
> 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.
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