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https://issues.apache.org/jira/browse/SSHD-911?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16822992#comment-16822992
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Goldstein Lyor commented on SSHD-911:
-------------------------------------
I have looked in the specified code area and its use, but have not found
anything suspicious. AFAIK there are no _lock-wait-until_ loops and the order
of the acquired locks seems consistent.
I have [made a change|https://github.com/apache/mina-sshd/pull/101] that while
does not explain the deadlock, perhaps mitigates it. Try cloning
[https://github.com/lgoldstein/mina-sshd/tree/SSHD-911] and using it to see if
it fixes or at least mitigates the issue - let me know.
Specifically, the {{ClientChannelPendingMessagesQueue}} is involved only in
port forwarding code, so it would seem that not only {quote}a quite large
number of client data connections (i.e 20/30 connections) are flowing to target
servers.{quote} but some of them are involved in port forwarding. Perhaps we
can somehow isolate them and figure out what they are doing that may cause a
deadlock (assuming it always deadlock at the same location).
> Deadlock in Apache SshClient used for local port forwarding
> -----------------------------------------------------------
>
> Key: SSHD-911
> URL: https://issues.apache.org/jira/browse/SSHD-911
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 2.2.0
> Reporter: Roberto Deandrea
> Assignee: Goldstein Lyor
> Priority: Major
> Attachments: [email protected]
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Hi Lyor,
> We have an Apache SSHD 2.2.0 client and server SSH pair used for local port
> forwarding of different protocols.
> In our lab environment we found that sometimes when the SSH client for any
> reason is disconnecting from the SSH server, a DEADLOCK happens on the
> sshClient regarding the threads in the thread pool.
> We are using builtin nio2 implementation for our SshClient.
> The deadlock is regarding the ClientChannelPendingMessagesQueue class added
> to fix routing problems for local port forwarding in the past.
> Attached you can find the thread dump taken after the deadlock happend.
>
> Can you please troubleshoot this problem ?
> [^[email protected]]
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