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https://issues.apache.org/jira/browse/ZOOKEEPER-1505?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13526854#comment-13526854
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Hadoop QA commented on ZOOKEEPER-1505:
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-1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12548952/ZOOKEEPER-1505.patch
against trunk revision 1415847.
+1 @author. The patch does not contain any @author tags.
+1 tests included. The patch appears to include 3 new or modified tests.
+1 javadoc. The javadoc tool did not generate any warning messages.
+1 javac. The applied patch does not increase the total number of javac
compiler warnings.
-1 findbugs. The patch appears to introduce 1 new Findbugs (version 1.3.9)
warnings.
+1 release audit. The applied patch does not increase the total number of
release audit warnings.
+1 core tests. The patch passed core unit tests.
+1 contrib tests. The patch passed contrib unit tests.
Test results:
https://builds.apache.org/job/PreCommit-ZOOKEEPER-Build/1288//testReport/
Findbugs warnings:
https://builds.apache.org/job/PreCommit-ZOOKEEPER-Build/1288//artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Console output:
https://builds.apache.org/job/PreCommit-ZOOKEEPER-Build/1288//console
This message is automatically generated.
> Multi-thread CommitProcessor
> ----------------------------
>
> Key: ZOOKEEPER-1505
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1505
> Project: ZooKeeper
> Issue Type: Improvement
> Components: server
> Affects Versions: 3.4.3, 3.4.4, 3.5.0
> Reporter: Jay Shrauner
> Assignee: Jay Shrauner
> Labels: performance, scaling
> Fix For: 3.5.0
>
> Attachments: ZOOKEEPER-1505.patch, ZOOKEEPER-1505.patch,
> ZOOKEEPER-1505.patch
>
>
> CommitProcessor has a single thread that both pulls requests off its queues
> and runs all downstream processors. This is noticeably inefficient for
> read-intensive workloads, which could be run concurrently. The trick is
> handling write transactions. I propose multi-threading this code according to
> the following two constraints
> - each session must see its requests responded to in order
> - all committed transactions must be handled in zxid order, across all
> sessions
> I believe these cover the only constraints we need to honor. In particular, I
> believe we can relax the following:
> - it does not matter if the read request in one session happens before or
> after the write request in another session
> With these constraints, I propose the following threads
> - 1 primary queue servicing/work dispatching thread
> - 0-N assignable worker threads, where a given session is always assigned
> to the same worker thread
> By assigning sessions always to the same worker thread (using a simple
> sessionId mod number of worker threads), we guarantee the first constraint--
> requests we push onto the thread queue are processed in order. The way we
> guarantee the second constraint is we only allow a single commit transaction
> to be in flight at a time--the queue servicing thread blocks while a commit
> transaction is in flight, and when the transaction completes it clears the
> flag.
> On a 32 core machine running Linux 2.6.38, achieved best performance with 32
> worker threads for a 56% +/- 5% improvement in throughput (this improvement
> was measured on top of that for ZOOKEEPER-1504, not in isolation).
> New classes introduced in this patch are:
> WorkerService (also in ZOOKEEPER-1504): ExecutorService wrapper that
> makes worker threads daemon threads and names then in an easily debuggable
> manner. Supports assignable threads (as used here) and non-assignable threads
> (as used by NIOServerCnxnFactory).
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