Xiaolin Ha created HBASE-25287:
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Summary: Forgetting to unbuffer streams results in many CLOSE_WAIT
sockets when loading files
Key: HBASE-25287
URL: https://issues.apache.org/jira/browse/HBASE-25287
Project: HBase
Issue Type: Bug
Affects Versions: 2.4.0
Reporter: Xiaolin Ha
Attachments: 1605328358304-image.png, 1605328417888-image.png,
1605504914256-image.png
[HBASE-9393|https://issues.apache.org/jira/browse/HBASE-9393] found seek+read
will leave many CLOSE_WAIT sockets without stream unbuffer, which can free
sockets and file descriptors held by the stream.
In our cluster RSes with about one hundred thousand store files, we found the
number of CLOSE_WAIT sockets increases with the number of regions opened, and
can up to the operating system open files limit 1000000.
{code:java}
2020-11-12 20:19:02,452 WARN [1282990092@qtp-220038608-1 - Acceptor0
[email protected]:16030] mortbay.log: EXCEPTION
java.io.IOException: Too many open files
at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method)
at
sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:422)
at
sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:250)
at
org.mortbay.jetty.nio.SelectChannelConnector$1.acceptChannel(SelectChannelConnector.java:75)
at
org.mortbay.io.nio.SelectorManager$SelectSet.doSelect(SelectorManager.java:686)
at org.mortbay.io.nio.SelectorManager.doSelect(SelectorManager.java:192)
at
org.mortbay.jetty.nio.SelectChannelConnector.accept(SelectChannelConnector.java:124)
at
org.mortbay.jetty.AbstractConnector$Acceptor.run(AbstractConnector.java:708)
at
org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
{code}
{code:java}
[hbase@gha-data-hbase-cat0053 hbase]$ ulimit -SHn
1000000
{code}
The reason of the problem is, when store file opened,
{code:java}
private void open() throws IOException {
fileInfo.initHDFSBlocksDistribution();
long readahead = fileInfo.isNoReadahead() ? 0L : -1L;
ReaderContext context = fileInfo.createReaderContext(false, readahead,
ReaderType.PREAD);
fileInfo.initHFileInfo(context);
StoreFileReader reader = fileInfo.preStoreFileReaderOpen(context, cacheConf);
if (reader == null) {
reader = fileInfo.createReader(context, cacheConf);
fileInfo.getHFileInfo().initMetaAndIndex(reader.getHFileReader());
}
....{code}
only createReader() unbuffered the stream. In initMetaAndIndex(), used the
stream to read blocks, so it need to unbuffer() the socket , too.
We can just add try before fileInfo.initHFileInfo(context); and finally
unbuffer() the stream at the end of the open() function.
We fixed it on our cluster, the number of CLOSE_WAIT reduced to about 0.
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