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https://issues.apache.org/jira/browse/SSHD-152?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Guillaume Nodet resolved SSHD-152.
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Resolution: Won't Fix
Assignee: Guillaume Nodet
Having sshd log send through the same sshd server to a client is quite a bad
idea. You may also end up in infinite log generation because sending some data
will generate more logs and so on.
The best idea in that case it to make sure that the underlying logging
framework (logback in your case) is configured to log sshd events at info
level, or to a file, but not to the console for example.
> Logging may cause deadlock.
> ---------------------------
>
> Key: SSHD-152
> URL: https://issues.apache.org/jira/browse/SSHD-152
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 0.5.0
> Reporter: Gunnar Wagenknecht
> Assignee: Guillaume Nodet
>
> I'm not really sure what I did but I think I somehow managed to deadlock my
> system using SSHD in combination with Logback console appender.
> Thread 1
> {noformat}
> Thread [Thread-21] (Suspended)
> owns: ChannelOutputStream (id=481)
> owns: ConsoleOutputStream (id=482)
> owns: PrintStream (id=483)
> owns: Object (id=202)
> waited by: Thread [...] (Suspended)
> waited by: Thread [...] (Suspended)
> waited by: Thread [...] (Suspended)
> waited by: Thread [NioProcessor-2] (Suspended)
> waited by: Thread [...] (Suspended)
> waited by: Thread [...] (Suspended)
> waited by: Thread [...] (Suspended)
> waited by: Thread [...] (Suspended)
> waited by: Thread [...] (Suspended)
> waited by: Thread [...] (Suspended)
> owns: OutputStreamWriter (id=484)
> waiting for: Window (id=485)
> Object.wait(long) line: not available [native method]
> Window(Object).wait() line: 503
> Window.waitForSpace() line: 146
> ChannelOutputStream.flush() line: 104
> ConsoleOutputStream.flush() line: 97
> ConsoleOutputStream.write(int) line: 83
> ConsoleOutputStream(OutputStream).write(byte[], int, int) line: 116
> PrintStream.write(byte[], int, int) line: 480
> PrintStream(FilterOutputStream).write(byte[]) line: 97
> ThreadPrintStream.write(byte[]) line: 245
> ConsoleTarget$1.write(byte[]) line: 36
> PatternLayoutEncoder(LayoutWrappingEncoder<E>).doEncode(E) line: 103
> ConsoleAppender<E>(OutputStreamAppender<E>).writeOut(E) line: 193
> ConsoleAppender<E>(OutputStreamAppender<E>).subAppend(E) line: 217
> ConsoleAppender<E>(OutputStreamAppender<E>).append(E) line: 108
> ConsoleAppender<E>(UnsynchronizedAppenderBase<E>).doAppend(E) line: 88
> AppenderAttachableImpl<E>.appendLoopOnAppenders(E) line: 64
> Logger.appendLoopOnAppenders(ILoggingEvent) line: 285
> Logger.callAppenders(ILoggingEvent) line: 272
> Logger.buildLoggingEventAndAppend(String, Marker, Level, String,
> Object[], Throwable) line: 473
> Logger.filterAndLog_2(String, Marker, Level, String, Object, Object,
> Throwable) line: 464
> Logger.debug(String, Object, Object) line: 542
> ChannelOutputStream.flush() line: 119
> ...
> {noformat}
> Thread 2
> {noformat}
> Thread [NioProcessor-2] (Suspended)
> owns: Object (id=150)
> waiting for: Object (id=202)
> owned by: Thread [Thread-21] (Suspended)
> waiting for: Window (id=485)
> ConsoleAppender<E>(OutputStreamAppender<E>).subAppend(E) line: 217
> ConsoleAppender<E>(OutputStreamAppender<E>).append(E) line: 108
> ConsoleAppender<E>(UnsynchronizedAppenderBase<E>).doAppend(E) line: 88
> AppenderAttachableImpl<E>.appendLoopOnAppenders(E) line: 64
> Logger.appendLoopOnAppenders(ILoggingEvent) line: 285
> Logger.callAppenders(ILoggingEvent) line: 272
> Logger.buildLoggingEventAndAppend(String, Marker, Level, String,
> Object[], Throwable) line: 473
> Logger.filterAndLog_1(String, Marker, Level, String, Object, Throwable)
> line: 445
> Logger.debug(String, Object) line: 538
> ServerSession.handleMessage(Buffer) line: 119
> ...
> {noformat}
> I think that one thread is waiting for Window to expand. The SSHD logger has
> a console appender. Unfortunately, the wait happends within a write by
> console appender. Thus all other threads that also log to the console will
> block because they wait for the Logback console appender lock.
> I think that a Logback console appender should not write to the SSHD console
> by default. Can this be disabled somehow?
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