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https://issues.apache.org/jira/browse/SSHD-939?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16927711#comment-16927711
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Anudeep edited comment on SSHD-939 at 9/11/19 4:00 PM:
-------------------------------------------------------
Please answer above questions just for the understanding and then you can
proceed with the closure.
was (Author: anudeepgangasani):
Please answer below and then you can proceed with the closure.
> SSH threads get blocked in Object.wait() method forever resulting in
> CLOSE_WAIT connections
> -------------------------------------------------------------------------------------------
>
> Key: SSHD-939
> URL: https://issues.apache.org/jira/browse/SSHD-939
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 0.13.0
> Reporter: Anudeep
> Assignee: Goldstein Lyor
> Priority: Major
> Attachments: svc-1-bnsiserv_06_09_2019-server.7z,
> svc-1-bnsiserv_thread.log
>
>
> Ssh threads get blocked in object.wait() for ever and if the count of such
> threads crosses 3 no more ssh requests are served.
> We had an analysis of the logs and from the thread model of apache we see the
> maximum number of I/O threads is number of cores +1 in our server the number
> of cores is 2.
> SO after three such blocked threads we are not able to open any new ssh
> connection.
> Can you please confirm if the above logic is correct .
>
> We too found a ticket raised in 0.14.0
> (https://issues.apache.org/jira/browse/SSHD-348)which says threads in blocked
> state are fixed with 0.14.0 so we need a confirmation from you if 0.14.0 will
> fix the threads to be released and do not hung the process even if there are
> more than 3 of such a kind.
>
> Logs from thread dumps
> {code:java}
> From the thread dump it looks like we have a deadlock, e.g.
> In one thread we're trying to send out data on an SSH connection, but we're
> waiting for "space"
> "pool-7-thread-2213" #2677 prio=5 os_prio=0 tid=0x00007f85554cc800 nid=0x61e3
> in Object.wait() [0x00007f84ea29f000]
> java.lang.Thread.State: WAITING (on object monitor)
> at java.lang.Object.wait(Native Method)
> at java.lang.Object.wait(Object.java:502)
> at org.apache.sshd.common.channel.Window.waitForSpace(Window.java:148)
> - locked <0x0000000764942ad8> (a
> org.apache.sshd.common.channel.Window)
> at
> org.apache.sshd.common.channel.ChannelOutputStream.flush(ChannelOutputStream.java:116)
> - eliminated <0x0000000764942c20> (a
> org.apache.sshd.common.channel.ChannelOutputStream)
> at
> org.apache.sshd.common.channel.ChannelOutputStream.write(ChannelOutputStream.java:84)
> - locked <0x0000000764942c20> (a
> org.apache.sshd.common.channel.ChannelOutputStream)
> at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
> at sun.nio.cs.StreamEncoder.implWrite(StreamEncoder.java:282)
> at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:125)
> - locked <0x0000000764943500> (a java.io.OutputStreamWriter)
> at java.io.OutputStreamWriter.write(OutputStreamWriter.java:207)
> at java.io.BufferedWriter.write(BufferedWriter.java:188)
> - locked <0x0000000764943500> (a java.io.OutputStreamWriter)
> at java.io.PrintWriter.write(PrintWriter.java:426)
> - locked <0x00000007649434d8> (a java.io.BufferedWriter)
> at java.io.PrintWriter.write(PrintWriter.java:443)
> In another thread, we trying to close the same connection
> "sshd-SshServer[1ae27e4e]-nio2-thread-3" #356 prio=5 os_prio=0
> tid=0x00000000015f6000 nid=0x30b8 waiting for monitor entry
> [0x00007f851ab9c000]
> java.lang.Thread.State: BLOCKED (on object monitor)
> at
> org.apache.sshd.common.channel.ChannelOutputStream.close(ChannelOutputStream.java:146)
> - waiting to lock <0x0000000764942c20> (a
> org.apache.sshd.common.channel.ChannelOutputStream)
> at
> com.ericsson.oss.nbi.connection.ssh.SshCommandContext.shutdown(SshCommandContext.java:146)
> at
> com.ericsson.oss.nbi.connection.ssh.SshCommand$ContextStarter.shutdown(SshCommand.java:104)
> at
> com.ericsson.oss.nbi.connection.ssh.SshCommand.destroy(SshCommand.java:78)
> at
> org.apache.sshd.server.channel.ChannelSession.doCloseImmediately(ChannelSession.java:242)
> at
> org.apache.sshd.common.util.CloseableUtils$AbstractCloseable.close(CloseableUtils.java:276)
> at
> org.apache.sshd.common.util.CloseableUtils$ParallelCloseable.doClose(CloseableUtils.java:182)
> at
> org.apache.sshd.common.util.CloseableUtils$SimpleCloseable.close(CloseableUtils.java:151)
> .... at
> org.apache.sshd.common.io.nio2.Nio2Session$1.onFailed(Nio2Session.java:199)
> at
> org.apache.sshd.common.io.nio2.Nio2CompletionHandler$2.run(Nio2CompletionHandler.java:41)
> at java.security.AccessController.doPrivileged(Native Method)
> at
> org.apache.sshd.common.io.nio2.Nio2CompletionHandler.failed(Nio2CompletionHandler.java:39)
> at
> org.apache.sshd.common.io.nio2.Nio2Session$1.onCompleted(Nio2Session.java:195)
> at
> org.apache.sshd.common.io.nio2.Nio2Session$1.onCompleted(Nio2Session.java:170)
> at
> org.apache.sshd.common.io.nio2.Nio2CompletionHandler$1.run(Nio2CompletionHandler.java:32)
> at java.security.AccessController.doPrivileged(Native Method)
> at
> org.apache.sshd.common.io.nio2.Nio2CompletionHandler.completed(Nio2CompletionHandler.java:30)
> at sun.nio.ch.Invoker.invokeUnchecked(Invoker.java:126)
> at sun.nio.ch.Invoker$2.run(Invoker.java:218)
> at
> sun.nio.ch.AsynchronousChannelGroupImpl$1.run(AsynchronousChannelGroupImpl.java:112)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
> at java.lang.Thread.run(Thread.java:748)
> {code}
>
> Theory for the number of I/O process threads
> {code:java}
> https://cwiki.apache.org/confluence/display/MINA/Configuring+Thread+Model
> I/O processor thread performs the actual read and write operation until the
> connection is closed.Each SocketAcceptor or SocketConnector creates its own
> I/O processor thread(s). You can configure the number of the I/O processor
> threads. The default maximum number of the I/O processor threads is the
> number of CPU cores + 1. {code}
>
>
>
>
>
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