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https://issues.apache.org/jira/browse/SSHD-855?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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jpalacios closed SSHD-855.
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Resolution: Duplicate
> CachingPublicKeyAuthenticator not clearing up closed sessions
> -------------------------------------------------------------
>
> Key: SSHD-855
> URL: https://issues.apache.org/jira/browse/SSHD-855
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 1.7.0
> Reporter: jpalacios
> Priority: Major
>
> I'm currently investigating an incident in a production environment which
> resulted in an {{OutOfMemoryError}}.
> According to the heap dump we are seeing massive object graphs made up of
> nested MINA's {{NioSocketSessions}}:
> {code:java}
> Thread -> ServerSessionImpl -> SshServer ->
> JohnsonAwarePublicKeyAuthenticator -> CachingPublicKeyAuthenticator ->
> ConcurrentHashMap -> ConcurrentHashMap$Node[] -> ConcurrentHashMap$Node ->
> ServerSessionImpl -> MinaSession -> NioSocketSession -> SelectionKeyImpl ->
> EpollSelectorImpl -> HashMap -> SelectionKeyImpl -> NioSocketSession -> ...
> {code}
> As you can see pass the first {{NioSocketSession}} the graph starts to repeat
> itself. These are not loops however. These are all different instances with a
> small shallow size but which add up to massive retained sizes. The
> {{CachingPublicKeyAuthenticator}} in particular has a retained size of ~6GB.
> Another interesting thing is that AFAICT out the 94K {{NioSocketSession}}
> instances in the heap, 93983 have a closed channel and the
> {{ServerSessionImpl}} that directly reference them is closed as well. 59 of
> these {{ServerSessionImpl}} instances are directly referenced from the
> {{cache}} map in {{CachingPublicKeyAuthenticator}}.
> I'm still gathering information to understand the load the system was in at
> the time of the incident, but I would appreciate your help in trying to
> understand how this nested graph could be put together, and if there's a
> scenario in which the {{CachingPublicKeyAuthenticator}} may fail to clear
> it's cached correctly.
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