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Hadoop QA commented on HDFS-5276: --------------------------------- {color:red}-1 overall{color}. Here are the results of testing the latest attachment http://issues.apache.org/jira/secure/attachment/12608402/HDFS-5276.003.patch against trunk revision . {color:green}+1 @author{color}. The patch does not contain any @author tags. {color:green}+1 tests included{color}. The patch appears to include 1 new or modified test files. {color:green}+1 javac{color}. The applied patch does not increase the total number of javac compiler warnings. {color:green}+1 javadoc{color}. The javadoc tool did not generate any warning messages. {color:red}-1 eclipse:eclipse{color}. The patch failed to build with eclipse:eclipse. {color:green}+1 findbugs{color}. The patch does not introduce any new Findbugs (version 1.3.9) warnings. {color:red}-1 release audit{color}. The applied patch generated 1 release audit warnings. {color:green}+1 core tests{color}. The patch passed unit tests in hadoop-common-project/hadoop-common. {color:green}+1 contrib tests{color}. The patch passed contrib unit tests. Test results: https://builds.apache.org/job/PreCommit-HDFS-Build/5188//testReport/ Release audit warnings: https://builds.apache.org/job/PreCommit-HDFS-Build/5188//artifact/trunk/patchprocess/patchReleaseAuditProblems.txt Console output: https://builds.apache.org/job/PreCommit-HDFS-Build/5188//console This message is automatically generated. > FileSystem.Statistics got performance issue on multi-thread read/write. > ----------------------------------------------------------------------- > > Key: HDFS-5276 > URL: https://issues.apache.org/jira/browse/HDFS-5276 > Project: Hadoop HDFS > Issue Type: Bug > Affects Versions: 2.0.4-alpha > Reporter: Chengxiang Li > Assignee: Colin Patrick McCabe > Attachments: DisableFSReadWriteBytesStat.patch, HDFS-5276.001.patch, > HDFS-5276.002.patch, HDFS-5276.003.patch, HDFSStatisticTest.java, > hdfs-test.PNG, jstack-trace.PNG, TestFileSystemStatistics.java, > ThreadLocalStat.patch > > > FileSystem.Statistics is a singleton variable for each FS scheme, each > read/write on HDFS would lead to a AutomicLong.getAndAdd(). AutomicLong does > not perform well in multi-threads(let's say more than 30 threads). so it may > cause serious performance issue. during our spark test profile, 32 threads > read data from HDFS, about 70% cpu time is spent on > FileSystem.Statistics.incrementBytesRead(). -- This message was sent by Atlassian JIRA (v6.1#6144)