[JAMES-3652] Avoid locking in protocol task execution

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.6.0
• Fix Version/s: 3.7.0
• Component/s: IMAPServer, POP3Server, SMTPServer
• Labels: perf
• Assignee: Unassigned
• Reporter: Benoit Tellier
• Created: 22/Sep/21 11:21
• Updated: 28/Sep/21 02:29
• Resolved: 28/Sep/21 02:29

Description

I found out the JMX executor wrapper of the Netty protocol transport layer was doing locks (synchronized lists and synchronized blocks).

On a regular SMTP worload (5000 mails of 500 KB) we spent 12.9% of CPU cycles doing locks... (See attached flame graphs)

We can easily implement the very same feature without any lock. Wich result in using 4.7 % only of CPU cycles.

Issue Links

• links to: GitHub Pull Request #666