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https://issues.apache.org/jira/browse/SSHD-854?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16664701#comment-16664701
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jpalacios commented on SSHD-854:
--------------------------------
[~johnnyv],
Picking one at random it's referenced by 11 {{SelectorKeyImpl}} instances and
one {{AbstractSelector$1}}. Then up the chain (which has a massive number of
links) those {{SelectorKeyImpl}} instances all go all the way back to the
{{CachingPublicKeyAuthenticator}}.
{code}
Thread -> ServerSessionImpl -> SshServer -> JohnsonAwarePublicKeyAuthenticator
-> CachingPublicKeyAuthenticator -> ConcurrentHashMap ->
ConcurrentHashMap$Node[] -> ConcurrentHashMap$Node -> ServerSessionImpl ->
MinaSession -> NioSocketSession -> SelectionKeyImpl -> EpollSelectorImpl ->
HashMap -> SelectionKeyImpl -> NioSocketSession -> ...
{code}
> Massive object graph in NioSocketSession
> ----------------------------------------
>
> Key: SSHD-854
> URL: https://issues.apache.org/jira/browse/SSHD-854
> Project: MINA SSHD
> Issue Type: Bug
> Reporter: jpalacios
> Priority: Major
>
> I'm looking at a heap dump from one of our customers where the retained heap
> size for some {{NioSocketSession}} instances is almost 1GB.
> From the looks of the dump MINA has created a massive object graph where:
> {code}
> NioSocketSession -> SelectionKeyImpl -> EpollSelectorImpl -> HashMap ->
> SelectionKeyImpl -> NioSocketSession -> ...
> {code}
> From the looks of the obeject IDs these are not loops
> Each individual object is not large by itself but at the top of the graph the
> accumulated retained size is enough to produce an OOME
> Could you help me understand how MINA can produce such a massive object
> graph? Should MINA apply any defense mechanism to prevent this??
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