How to customize my log4j2.xml parameters

Question

I'm new to using log4j 2. I just started, and prepared the following log4j2.xml configuration file:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="INFO">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%msg%n" />
        </Console>
        <File name="MyFile" fileName="manager.log" immediateFlush="true" append="false">
            <PatternLayout pattern="%d{yyy-MM-dd HH:mm:ss} [%t] %-5level %logger{36} - %msg%n"/>
        </File>
    </Appenders>
    <Loggers>
        <Root level="debug">
            <AppenderRef ref="Console" />
            <AppenderRef ref="MyFile"/>
        </Root>
    </Loggers>
</Configuration>

What is the default logging behavior and file size in my xml? Is it rolling file, or once per day, or just a single huge file that grows a default size?!

If not, how can I change it to 2 rolling files with max of 10mb?

What research have you done? Have you read the log4j2 manual? — D.B.
– D.B., Commented Jan 9, 2019 at 5:24

Remko Popma · Accepted Answer · 2019-01-09 01:43:36Z

1

The File appender doesn’t have rollover behavior, it just appends to the specified file. When append = "false", it will overwrite any existing file when the application is restarted.

The Rolling File Appender is probably what you’re looking for.

The manual has many examples, but this may be close to what you have in mind:

1   <?xml version="1.0" encoding="UTF-8"?>
2   <Configuration status="warn" name="MyApp" packages="">
3     <Appenders>
4       <RollingFile name="RollingFile" fileName="logs/app.log"
5                    filePattern="logs/$${date:yyyy-MM}/app-%d{MM-dd-yyyy}-%i.log.gz">
6         <PatternLayout>
7           <Pattern>%d %p %c{1.} [%t] %m%n</Pattern>
8         </PatternLayout>
9         <Policies>
10          <TimeBasedTriggeringPolicy />
11          <SizeBasedTriggeringPolicy size="10 MB"/>
12        </Policies>
13        <DefaultRolloverStrategy max="2"/>
14      </RollingFile>
15    </Appenders>
16    <Loggers>
17      <Root level="error">
18        <AppenderRef ref="RollingFile"/>
19      </Root>
20    </Loggers>
21  </Configuration>

answered Jan 9, 2019 at 1:43

Remko Popma

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6 Comments

angel_30 Over a year ago

So how big in size will the default file (my code) get?

Remko Popma Over a year ago

There’s no limit, depends on how much your application logs. If the application is never restarted it may run out of disk space eventually.

angel_30 Over a year ago

oh I see! Then I have to switch to your code! Thanks.

angel_30 Over a year ago

One question: Why there is still a parent app.log?! I get this as well as the two rolling files.

Remko Popma Over a year ago

The app.log file is what Log4j is currently writing to. If a rollover condition is met, Log4j will “roll over” the current file (rename, move to other directory and compress it). It will then create a new “current log file” to append log events to.

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