How to use policies on dynamic log file name?

I'm using Log4j2 and I need my logs to:

1. Include the current date and process idin the active log file name (e.g., logname.529628.27-04-2025.log)
2. create new log based on file size (for example, every 10MB)
3. Keep only a maximum number of old files (like 10 backups)

this is what i have now :

<?xml version="1.0" encoding="UTF-8"?>

<Properties>
    <Property name="LOG_PATTERN">
        %-40.40c{1.} : %notEmpty{%m}%n%ex
    </Property>
    <Property name="PID">${sys:PID}</Property>
    <Property name="FS">${sys:file.separator}</Property>
    <Property name="log-path">log${sys:file.separator}</Property>
    <Property name="log-pattern">%d{yyyy-MM-dd HH:mm:ss,SSS} PID:${sys:PID} %-2p [T@%tid-%t] [%F:%L] %notEmpty{%marker} %m%n</Property>
</Properties>

<Appenders>
    <Routing name="Routing">
        <Routes pattern="$${sys:logName}">
            <Route key="testlog">
                <RollingFile name="ArchiveLog" fileName="${log-path}logname.${sys:PID}.${date:dd-MM-yyyy}.log"
                             filePattern="${log-path}logname.${sys:PID}.${date:dd-MM-yyyy}.%i.log">
                    <PatternLayout pattern="${log-pattern}"/>
                    <Policies>
                        <SizeBasedTriggeringPolicy size="10MB"/>
                    </Policies>
                    <DefaultRolloverStrategy max="10">
                    </DefaultRolloverStrategy>
                </RollingFile>
            </Route>
        </Routes>
    </Routing>
</Appenders>

<Loggers>
    <Logger name="logname" level="trace" additivity="false">
        <AppenderRef ref="Routing" />
    </Logger>
    <Root level="info">
        <AppenderRef ref="Routing"/>
    </Root>
</Loggers>

But it seems rotation by size is not working correctly on dynamic file name. any ideas?

thanks!

The rotation isn’t working because Log4j2’s RollingFile appender needs the active fileName to stay static, adding ${date} there confuses the rollover.

To fix it, keep fileName simple and static, and use the %d pattern only in filePattern so Log4j2 can handle size-based rotation and backups properly.

Replace your <RollingFile> with this:

<RollingFile name="ArchiveLog"
             fileName="${log-path}logname.${sys:PID}.current.log"
             filePattern="${log-path}logname.${sys:PID}.%d{dd-MM-yyyy}.%i.log">
    <PatternLayout pattern="${log-pattern}"/>
    <Policies>
        <SizeBasedTriggeringPolicy size="10MB"/>
    </Policies>
    <DefaultRolloverStrategy max="10"/>
</RollingFile>