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https://issues.apache.org/jira/browse/LOG4J2-812?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14614321#comment-14614321
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Gary Gregory edited comment on LOG4J2-812 at 7/5/15 5:25 PM:
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{quote}I am not crazy about this solution simply because I am not crazy about
having a ThreadLocal per DatePatternConverter.{quote}
Why? How many DatePatternConverter's can there be in an application? I guess
some apps could create hundreds of file appenders for different data based on
markers. But if you do that, you're going to have a lot of overhead anyway.
If an app has a lot of thread coming and going, that means a lot of thread
locals coming and going as well. Is that the issue you are worried about?
Does Java 8's new date-time code offer lock free formatting?
was (Author: garydgregory):
{quote}I am not crazy about this solution simply because I am not crazy about
having a ThreadLocal per DatePatternConverter.{quote}
Why? How many DatePatternConverter's can there be in an application? I guess
some apps could create hundreds of file appenders for different data based on
markers. But if you do that, you're going to have a lot of overhead anyway.
Does Java 8's new date-time code offer lock free formatting?
> 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
>
> Attachments: LOG4J2-812-patch.txt
>
>
> 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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