[LOG4J2-812] Performance optimization: avoid use of synchronized SimpleDateFormat in Dat​ePatternCo​nverter

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.2
• Fix Version/s: 2.4
• Component/s: Pattern Converters, Performance Benchmarks
• Assignee: Ralph Goers
• Reporter: Mohit Anchlia
• Created: 03/Sep/14 23:38
• Updated: 22/Aug/15 13:32
• Resolved: 22/Aug/15 13:25

Description

Threads seem to be blocking on class org.apache​.loggin.lo​g4j.core.p​attern.Dat​ePatternCo​nverter. It's short lived but is visible in profiler. It also is adding on to CPU. Here is the mail conversation on the mailing list:

Ralph Goers [e-mail] via logging.apache.org

The converter uses a SimpleDateFormat which is not thread safe and so is synchronized. I am sure there might be minor optimizations that could be done to this

What I would do is modify DatePatternConverter to
a) use Java 8’s java.time.format.DateTimeFormatter if running on Java 8
b) use Joda Time’s DateTimeFormat if it is present.
c) create a pool of SimpleDateFormat objects and use those.

Please create a Jira issue for this.

Ralph

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One alternative that was suggested on the mailing list is to use commons lang FastDateFormat to format log timestamps.

Issue Links

• is depended upon by: LOG4J2-1097 [Perf] Custom TimeFormat
• is depended upon by: LOG4J2-930 Improve PatternLayout performance
• is duplicated by: LOG4J2-852 [Perf] Use FastDateFormat to format %d timestamps
• is related to: LOG4J2-1102 Follow up: remaining tasks related to introducing FastDateFormat