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https://issues.apache.org/jira/browse/HDFS-9023?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16302920#comment-16302920
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Surendra Singh Lilhore commented on HDFS-9023:
----------------------------------------------
Thanks [~xiaochen] for the patch. V2 patch almost looks good to me.
Some minor comment..
# No need to put {{if (LOG.isDebugEnabled() && builder != null)}} check in else
part. Already {{LOG.isDebugEnabled()}} check done in first {{if}}. So it shoud
be like this.
{code}
if (LOG.isDebugEnabled() && builder != null) {
detail = builder.toString();
if (badTarget) {
builder.setLength(0);
} else {
if (detail.length() > 1) {
// only log if there's more than "[", which is always appended at
// the beginning of this method.
LOG.debug(builder.toString());
}
detail = "";
}
}
{code}
# Just give the HashMap generic paramter here.
{code}+ HashMap reasonMap = CHOOSE_RANDOM_REASONS.get();{code}
# Log message should be {{warn}}
{code}+ LOG.info("Not enough replicas was chosen. Reason:{}",
reasonMap);{code}
> When NN is not able to identify DN for replication, reason behind it can be
> logged
> ----------------------------------------------------------------------------------
>
> Key: HDFS-9023
> URL: https://issues.apache.org/jira/browse/HDFS-9023
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs-client, namenode
> Affects Versions: 2.7.1
> Reporter: Surendra Singh Lilhore
> Assignee: Xiao Chen
> Priority: Critical
> Attachments: HDFS-9023.01.patch, HDFS-9023.02.patch
>
>
> When NN is not able to identify DN for replication, reason behind it can be
> logged (at least critical information why DNs not chosen like disk is full).
> At present it is expected to enable debug log.
> For example the reason for below error looks like all 7 DNs are busy for data
> writes. But at client or NN side no hint is given in the log message.
> {noformat}
> File /tmp/logs/spark/logs/application_1437051383180_0610/xyz-195_26009.tmp
> could only be replicated to 0 nodes instead of minReplication (=1). There
> are 7 datanode(s) running and no node(s) are excluded in this operation.
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:1553)
>
> {noformat}
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