[ https://issues.apache.org/jira/browse/HDFS-5276?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Chengxiang Li updated HDFS-5276: -------------------------------- Attachment: jstack-trace.PNG hdfs-test.PNG HDFSStatisticTest.java i write a simple test case, run it on a (4 node, each 32 core) cluster, which reproduce this issue. > 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 > Attachments: HDFSStatisticTest.java, hdfs-test.PNG, jstack-trace.PNG > > > 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 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)