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https://issues.apache.org/jira/browse/IMAP-371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13629971#comment-13629971
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Andrzej Rusin commented on IMAP-371:
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Eric,
I was thinking about it more and my next idea is:
- SelectedMailbox is the context of "most" commands, esp in the context of the
count of invocations,
- the MessageManager from
org.apache.james.mailbox.store.StoreMailboxManager.getMailbox(MailboxPath,
MailboxSession) is mostly used for
org.apache.james.mailbox.MessageManager.getMetaData(boolean, MailboxSession,
FetchGroup)
- so maybe keeping/deriving a MessageManager in/from SelectedMailbox may
totally eliminate getting the Mailbox from MailboxMapper in
org.apache.james.mailbox.store.StoreMailboxManager.getMailbox(MailboxPath,
MailboxSession)?
- especially that "most" commands inherit
org.apache.james.imap.processor.AbstractMailboxProcessor, and this fact can
somehow be used.
What do you think?
Still, my first solution reduces getting the Mailbox by fair amount.
> MailboxManager::getMailbox called very often
> --------------------------------------------
>
> Key: IMAP-371
> URL: https://issues.apache.org/jira/browse/IMAP-371
> Project: James Imap
> Issue Type: Improvement
> Components: Processor
> Affects Versions: 0.3
> Reporter: Andrzej Rusin
> Assignee: Eric Charles
>
> MailboxManager::getMailbox(MailboxPath mailboxPath, MailboxSession session)
> is getting called extremely often.
> On my custom RDBMS-based Mailstore implementation it is the biggest hot spot.
> I had to resort to caching the return value of it on Memcache, but even after
> that it uses up around 15% of spent CPU time. It is far too much in my
> opinion. (before I started caching it, fully indexed RDBMS getting of the
> mailbox was taking more than 50% of the global RDBMS load).
> My suspect is the method AbstractMailboxProcessor::addFlagsResponses(final
> ImapSession session, final SelectedMailbox selected, final
> ImapProcessor.Responder responder, boolean useUid).
> It gets the mailbox from MessageManager each time, even if it may be not
> needed.
> This method is called in many CommandProcessors during the
> unsolicitedResponses phase.
> After I am able to really profile and confirm that it's the core of problem,
> I will provide a patch.
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