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From "Andrzej Rusin (JIRA)" <server-...@james.apache.org>
Subject [jira] [Commented] (IMAP-371) MailboxManager::getMailbox called very often
Date Fri, 12 Apr 2013 10:22:15 GMT

    [ https://issues.apache.org/jira/browse/IMAP-371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13629971#comment-13629971

Andrzej Rusin commented on IMAP-371:

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,
- 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
> 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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