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https://issues.apache.org/jira/browse/SSHD-1058?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17179453#comment-17179453
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Markus Spann commented on SSHD-1058:
------------------------------------
Thanks for pointing out issue SSHD-977 which I was not aware of.
I utilize sshd to offer an administrative rmi console in an application. RMI
commands also get executed by scripts e.g. checking system health/status
periodically.
Every such invocation causes an error log now.
We are being called in destroy(ChannelSession) by
ChannelSession#closeImmediately0. We then go on by calling
AbstractTerminal#close which ultimately gets the WindowClosedException in
Window#waitForCondition.
I am wondering whether the solution is to NOT close the terminal after #destroy
was called?
(Our stackframes start with my.app.rmi)
{noformat}
2020-08-17 11:22:43,969 ERROR [sshd-pool-thread-10]
server.channel.ChannelSession - flush(ChannelOutputStream[ChannelSession[id=0,
recipient=0]-ServerSessionImpl[rmiadmin@/0:0:0:0:0:0:0:1:58844]]
SSH_MSG_CHANNEL_DATA) wait for space len=1 exception details
org.apache.sshd.common.channel.WindowClosedException: Already closed:
Window[server/remote](ChannelSession[id=0,
recipient=0]-ServerSessionImpl[rmiadmin@/0:0:0:0:0:0:0:1:58844])
at org.apache.sshd.common.channel.Window.waitForCondition(Window.java:304)
at org.apache.sshd.common.channel.Window.waitForSpace(Window.java:255)
at
org.apache.sshd.common.channel.ChannelOutputStream.flush(ChannelOutputStream.java:197)
at
org.apache.sshd.common.channel.ChannelOutputStream.close(ChannelOutputStream.java:271)
at
org.jline.terminal.impl.LineDisciplineTerminal$FilteringOutputStream.close(LineDisciplineTerminal.java:306)
at java.base/sun.nio.cs.StreamEncoder.implClose(StreamEncoder.java:341)
at java.base/sun.nio.cs.StreamEncoder.close(StreamEncoder.java:161)
at java.base/java.io.OutputStreamWriter.close(OutputStreamWriter.java:258)
at java.base/java.io.PrintWriter.close(PrintWriter.java:415)
at
org.jline.terminal.impl.LineDisciplineTerminal.doClose(LineDisciplineTerminal.java:270)
at org.jline.terminal.impl.ExternalTerminal.doClose(ExternalTerminal.java:89)
at org.jline.terminal.impl.AbstractTerminal.close(AbstractTerminal.java:95)
at
my.app.rmi.server.ssh.AbstractEmbeddedShell.close(AbstractEmbeddedShell.java:569)
at my.app.rmi.server.ssh.EmbeddedShell.close(EmbeddedShell.java:270)
at
my.app.rmi.server.ssh.AbstractEmbeddedShell.destroy(AbstractEmbeddedShell.java:515)
at
org.apache.sshd.server.channel.ChannelSession.closeImmediately0(ChannelSession.java:213)
at
org.apache.sshd.common.util.closeable.Builder$1.doClose(Builder.java:47){noformat}
> ChannelOutputStream#flush should not log at error level
> -------------------------------------------------------
>
> Key: SSHD-1058
> URL: https://issues.apache.org/jira/browse/SSHD-1058
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 2.5.0, 2.5.1
> Environment: Linux, Java 11
> Reporter: Markus Spann
> Assignee: Lyor Goldstein
> Priority: Minor
>
> When calling flush on ChannelOutputStream, Window.waitForSpace may throw a
> WindowClosedException. This exception is always logged at error level, then
> rethrown. If Debug is enabled on the logger, the error log is issued twice
> (second time with stacktrace).
> During deinitialization it is common practice to call flush on output
> streams. Due to the asynchronous nature of the code in this library, the call
> may fail. The caller should decide how to deal with the exception and log at
> error level if needed.
> The implementation should not log at error level regardless.
> I would suggest INFO level instead (if logging at all).
>
> {code:java}
> // lines 202 ff.
> if (log.isDebugEnabled()) {
> log.info("flush({}) failed ({}) to wait for space of len={}: {}: ", this,
> e.getClass().getSimpleName(), total, e.getMessage(), e); // with stacktrace
> } else {
> log.info("flush({}) failed ({}) to wait for space of len={}: {}",
> this, e.getClass().getSimpleName(), total, e.getMessage());
> }
> throw e;
> {code}
> Thanks,
> Markus
>
>
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