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https://issues.apache.org/jira/browse/LOG4J2-812?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14614174#comment-14614174
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Remko Popma commented on LOG4J2-812:
------------------------------------
I added JMH benchmark
/log4j-perf/src/main/java/org/apache/logging/log4j/perf/jmh/SimpleDateFormatBenchmark.
Results:
*1 Thread: almost no difference*
{code}
java -jar log4j-perf/target/benchmarks.jar ".*SimpleDateFormat.*" -f 1 -wi 5 -i
10 -t 1 -si true
Benchmark Mode Samples
Score Error Units
o.a.l.l.p.j.SimpleDateFormatBenchmark.baseline sample 108801
18.976 ± 1.142 ns/op
o.a.l.l.p.j.SimpleDateFormatBenchmark.synchronizedFormat sample 123187
374.147 ± 7.128 ns/op
o.a.l.l.p.j.SimpleDateFormatBenchmark.threadLocalFormat sample 127111
351.628 ± 15.233 ns/op
{code}
*4 Threads: contended lock is ~20x slower than threadlocal*
{code}
java -jar log4j-perf/target/benchmarks.jar ".*SimpleDateFormat.*" -f 1 -wi 5 -i
10 -t 4 -si true
Benchmark Mode Samples
Score Error Units
o.a.l.l.p.j.SimpleDateFormatBenchmark.baseline sample 448270
27.179 ± 1.565 ns/op
o.a.l.l.p.j.SimpleDateFormatBenchmark.synchronizedFormat sample 544613
13362.691 ± 376.438 ns/op
o.a.l.l.p.j.SimpleDateFormatBenchmark.threadLocalFormat sample 443271
779.043 ± 37.221 ns/op
{code}
> Performance optimization: avoid use of synchronized SimpleDateFormat in
> DatePatternConverter
> -----------------------------------------------------------------------------------------------
>
> Key: LOG4J2-812
> URL: https://issues.apache.org/jira/browse/LOG4J2-812
> Project: Log4j 2
> Issue Type: Bug
> Components: Pattern Converters, Performance Benchmarks
> Affects Versions: 2.0.2
> Reporter: Mohit Anchlia
> Assignee: Remko Popma
> Fix For: 2.3
>
>
> Threads seem to be blocking on class
> org.apache.loggin.log4j.core.pattern.DatePatternConverter. 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:
> {quote}
> Ralph Goers [email protected] 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
> {quote}
> ----
> One alternative that was suggested on the mailing list is to use commons
> lang FastDateFormat to format log timestamps.
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