[MIME4J-298] DateTimeFieldLenientImpl: Migrate from SimpleDateFormat to DateTimeFormatter

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.8.5
• Fix Version/s: 0.8.6
• Component/s: dom
• Assignee: Unassigned
• Reporter: Benoit Tellier
• Created: 16/May/21 11:31
• Updated: 20/Jun/21 02:45
• Resolved: 20/Jun/21 02:45

Description

SimpleDateFormat is instanciated for each invocation of DateTimeFieldLenientImpl::parse because SimpleDateFormat is not thread safe.

Using DateTimeFormatter would allow us to initialize it once at class-loading time.

Furthermore we should order the time formats so that the most frequents show up first, limiting the total count of parsing passes.

A simple flame graph study showed date parsing represents 20% of the CPU time when computing a MessageFastView projection, almost comparable to the full header parsing... I would like to lower that CPU time!

Reopen of https://issues.apache.org/jira/browse/JAMES-3584 on the right bug tracker.