[JAMES-3577] Tiny IMAP performance enhancements

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Component/s: IMAPServer
• Labels: perf
• Assignee: Unassigned
• Reporter: Benoit Tellier
• Created: 04/May/21 09:21
• Updated: 04/May/21 10:13
• Resolved: 04/May/21 10:13

Description

Auditing IMAP load with glowroot I was surprised to see thousands of calls to the highest Message UID within a mailbox.

For instance out of 500 MOVE commands the highest UID was checked a thousand time...

A deeper look at the code shows that the latest UID is agressively read before a IF loop not requiring it all of the time... When no `*` are specified in the range definition we can entirely skip this read... Which seems quitte of a common pattern!

Impacted commands includes:

• MOVE
• COPY
• STORE
• EXPUNGE
• FETCH

By not performing these reads I expect a minor performance increase...

• Something like7% for MOVE for instance.

I will report other tiny enhancements I can find as comments of this ticket.