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https://issues.apache.org/jira/browse/HDFS-9198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16726664#comment-16726664
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He Xiaoqiao commented on HDFS-9198:
-----------------------------------
Thanks [~daryn] for the nice work, and it is very useful for me. I am confused
about the following code, LOG means block report queue is full now, however the
IF statement is about how long from lastFull to now. Why not use queue size to
estimate if queue is full or not directly？
{code:java}
void enqueue(Runnable action) throws InterruptedException {
if (!queue.offer(action)) {
if (!isAlive() && namesystem.isRunning()) {
ExitUtil.terminate(1, getName() + " is not running");
}
long now = Time.monotonicNow();
if (now - lastFull > 4000) {
lastFull = now;
LOG.info("Block report queue is full");
}
queue.put(action);
}
}
{code}
If I missed something, please correct me. Thanks again.
> Coalesce IBR processing in the NN
> ---------------------------------
>
> Key: HDFS-9198
> URL: https://issues.apache.org/jira/browse/HDFS-9198
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 2.0.0-alpha
> Reporter: Daryn Sharp
> Assignee: Daryn Sharp
> Priority: Major
> Fix For: 2.8.0, 2.7.3, 3.0.0-alpha1
>
> Attachments: HDFS-9198-Branch-2-withamend.diff,
> HDFS-9198-Branch-2.8-withamend.diff, HDFS-9198-branch-2.7.patch,
> HDFS-9198-branch2.patch, HDFS-9198-trunk.patch, HDFS-9198-trunk.patch,
> HDFS-9198-trunk.patch, HDFS-9198-trunk.patch, HDFS-9198-trunk.patch
>
>
> IBRs from thousands of DNs under load will degrade NN performance due to
> excessive write-lock contention from multiple IPC handler threads. The IBR
> processing is quick, so the lock contention may be reduced by coalescing
> multiple IBRs into a single write-lock transaction. The handlers will also
> be freed up faster for other operations.
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