Log4j2 with MemoryMappedFile and break files

Question

Is that possible to use MemoryMappedFile with Policies to break the files until fixed sizes, for example 250MB? My log4j2.xml is like this but I want to break the log files to 250MB and I need to use MemoryMappedFile for IO performance.

<Configuration monitorInterval="30">
    <Appenders>
        <MemoryMappedFile name="MemoryMap" fileName="output/jscsi-out.log">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} %-5p [%t] %c{2} - %m%n(%L)" />
            <Policies>
                <TimeBasedTriggeringPolicy />
                <SizeBasedTriggeringPolicy size="250 MB" />
            </Policies>
        </MemoryMappedFile>
    </Appenders>

    <Loggers>
        <Logger name="br.com" level="debug" additivity="false">
            <AppenderRef ref="MemoryMap" />
        </Logger>
        <Logger name="org.jscsi.target.TargetServer" level="debug"
            additivity="false">
            <AppenderRef ref="MemoryMap" />
        </Logger>
        <Logger name="org.jscsi.target.storage" level="info"
            additivity="false">
            <AppenderRef ref="MemoryMap" />
        </Logger>
        <Logger name="org.jscsi.service" level="debug" additivity="false">
            <AppenderRef ref="MemoryMap" />
        </Logger>
        <Root level="error" includeLocation="true">
            <AppenderRef ref="MemoryMap" />
        </Root>
    </Loggers>
</Configuration>

Answer 1

(Background: I am the author of the MemoryMappedFile appender as well as Async Loggers.)

In some sense the MemoryMappedFile appender is still a work in progress (as of Log4j 2.5). As you mention, there is no Rolling variant. Also, I haven't been able to do any significant performance testing. I made a start some time ago but other issues took priority.

Initial performance testing indicates that synchronous logging, even when using the MemoryMappedFile appender, is unlikely to be faster than asynchronous logging via Async Loggers.

Generally, if you need the rollover behaviour I would suggest you use Async Loggers in combination with the RollingRandomAccessFile appender for now.