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From "Gary Gregory (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (LOG4J2-812) Performance optimization: avoid use of synchronized SimpleDateFormat in Dat​ePatternCo​nverter
Date Sun, 05 Jul 2015 17:26:05 GMT

    [ https://issues.apache.org/jira/browse/LOG4J2-812?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14614321#comment-14614321
] 

Gary Gregory edited comment on LOG4J2-812 at 7/5/15 5:25 PM:
-------------------------------------------------------------

{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 threads 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.

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?

> Performance optimization: avoid use of synchronized SimpleDateFormat in Dat​ePatternCo​nverter

> -----------------------------------------------------------------------------------------------
>
>                 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.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:
> {quote}
> Ralph Goers ralph.goers@dslextreme.com 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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