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https://issues.apache.org/jira/browse/LOG4J2-812?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14147282#comment-14147282
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Gary Gregory commented on LOG4J2-812:
-------------------------------------
I'm not sure using a different formatter would help.
In {{org.apache.logging.log4j.core.pattern.DatePatternConverter}} I see code
like:
{code:java}
/**
* Append formatted date to string buffer.
*
* @param date
* date
* @param toAppendTo
* buffer to which formatted date is appended.
*/
public void format(final Date date, final StringBuilder toAppendTo) {
synchronized (this) {
toAppendTo.append(formatter.format(date.getTime()));
}
}
/**
* {@inheritDoc}
*/
@Override
public void format(final LogEvent event, final StringBuilder output) {
final long timestamp = event.getTimeMillis();
synchronized (this) {
if (timestamp != lastTimestamp) {
lastTimestamp = timestamp;
cachedDateString = formatter.format(timestamp);
}
}
output.append(cachedDateString);
}
{code}
It is not just access to the formatter that is synchronized, but to the whole
caching logic.
Am I missing something?
What if the {{DatePatternConverter}} was a thread local?
> 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: 2.2
>
>
> 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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