The problem with the strange performance result is because of the
configuration:
You have includeLocation=true. This will force Log4j to take a snapshot of
the stack and is very slow.
Your layouts do not actually use this information, and this explains why
synchronous logging is faster: synchronous logging will _only_ take a
snapshot of the stack when the layout needs it. In your case this is never,
so you get fast performance.
The solution is to change your config to
<Root level="info" includeLocation="false">
If you test this with async loggers you should see a performance
improvement immediately.
On Sun, Oct 11, 2015 at 12:21 PM, Strong Su <lovelo...@gmail.com> wrote:
> My log4j2 sync configuration is:
>
> <?xml version="1.0" encoding="UTF-8"?>
> <Configuration>
> <Appenders>
> <!-- Async Loggers will auto-flush in batches, so switch off
> immediateFlush. -->
> <File name="File" fileName="{PATH}/a.log"
> immediateFlush="false" append="false">
> <PatternLayout pattern="%d %-5p [%c{2}] %m%n"/>
> </File>
> <Console name="STDOUT" target="SYSTEM_OUT">
> <PatternLayout pattern="%d %-5p [%c{2}] %m%n"/>
> </Console>
> </Appenders>
>
> <Loggers>
> <Root level="info" includeLocation="true">
> <AppenderRef ref="File"/>
> <AppenderRef ref="STDOUT"/>
> </Root>
> </Loggers>
>
> </Configuration>
>
> And async configuration change <Root> to <AsyncRoot>
>
> On Sun, Oct 11, 2015 at 10:51 AM, Remko Popma <remko.po...@gmail.com>
> wrote:
>
> > Can you post your log4j2 configuration?
> >
> > Sent from my iPhone
> >
> > > On 2015/10/10, at 21:58, Strong Su <lovelo...@gmail.com> wrote:
> > >
> > > I insert a log in a http request function on server side. And I start
> > > requests continually on client side through hundreds of threads.
> > > I measure the performance through QPS because server has to print a log
> > > whenever it receive a request. The time delayed by logging will
> influence
> > > QPS heavily.
> > > When I didn't insert a log in the request function, QPS was about
> 20000.
> > > When I inserted a log4j1 log, QPS was about 10000.
> > > When I inserted a log4j2 sync log, QPS was about 18000.
> > > But when I inserted a log4j2 asycn log, QPS was only about 5000.
> > >
> > >> On Sat, Oct 10, 2015 at 8:34 PM, Remko Popma <remko.po...@gmail.com>
> > wrote:
> > >>
> > >> How did you measure the good performance (with sync logging) and the
> bad
> > >> performance (with async)? What happens exactly when "it turns
> terrible"?
> > >>
> > >>> On Saturday, 10 October 2015, Strong Su <lovelo...@gmail.com> wrote:
> > >>>
> > >>> Hello everyone,
> > >>> I'm still testing log4j2 on our projects.
> > >>> When using it, I find it has a beautiful performance when using sync
> > >>> log4j2.
> > >>> But it turns terrible when I add -DLog4jContextSelector or change
> > <root>
> > >> to
> > >>> <AsyncRoot> in log4j2.xml to use async log4j2.
> > >>> I don't even have a clue on explaining this.What could cause this
> > bizarre
> > >>> problem?
> > >>>
> > >>> Thank you.
> > >>> Best regards,
> > >>> Dylan Su
> > >>
> >
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> >
> >
>
