log4j2 高性能

原创: http://www.imet.me/post/2018/07-18_log4j2_high_performance/

开篇词

log4j2 日志性能在某些场景下要优于 logback 等其他日志组件，带来了非常大的性能提升，究竟有多大呢？

这几个新的特性如下:

• Asynchronous Loggers based on the [LMAX Disruptor library]
• Garbage-free
• Plugin system, 方便添加 appenders, filters, layouts, lookups 等

高性能的几个表现对比 (High performance)

1. 日志组件之间的对比

结论：log4j2 all async 胜出，异步是同步的6-10倍

主要得益于:

• lock-free data structure

(refer: log4j2 performance)

2. 异步日志场景下是否记录调用栈

结论：不记录相关的 class, line num 这些信息的话，性能有 30~100 的提升

如果日志 pattern 中打印以下信息的话: %C or $class, %F or %file, %l or %location, %L or %line, %M or %method
将会极大的影响日志的性能，日志组件需要打印当前栈的快照，遍历 stack trace 然后找到 location 等相关信息

(refer: log4j2 performance)

3. 同步场景下 garbage free

大部分情况下 garbage free 的性能要优

(refer: log4j2 performance, garbagefree)

log4j2 相关的配置

maven pom 相关的配置

.pom.xml

  <dependencies>
    
    <dependency>
        <groupId>org.slf4jgroupId>
        <artifactId>slf4j-apiartifactId>
        <version>1.7.25version>
    dependency>

    
    <dependency>
        <groupId>org.apache.logging.log4jgroupId>
        <artifactId>log4j-slf4j-implartifactId>
        <version>2.10.0version>
    dependency>

    
    <dependency>
        <groupId>org.apache.logging.log4jgroupId>
        <artifactId>log4j-apiartifactId>
        <version>2.10.0version>
    dependency>

    
    <dependency>
        <groupId>org.apache.logging.log4jgroupId>
        <artifactId>log4j-coreartifactId>
        <version>2.10.0version>
    dependency>

    
    <dependency>
        <groupId>org.apache.logging.log4jgroupId>
        <artifactId>log4j-1.2-apiartifactId>
        <version>2.10.0version>
    dependency>

    
    
        
        
        
    

    
    <dependency>
        <groupId>com.lmaxgroupId>
        <artifactId>disruptorartifactId>
        <version>3.3.7version>
    dependency>

    
    <dependency>
      <groupId>xxxgroupId>
      <artifactId>xxx-yyartifactId>
      <version>zzversion>
      <exclusions>
        <exclusion>
            <artifactId>slf4j-log4j12artifactId>
            <groupId>org.slf4jgroupId>
        exclusion>
        <exclusion>
            <artifactId>log4jartifactId>
            <groupId>log4jgroupId>
        exclusion>
      exclusions>
    dependency>

  dependencies>

log4j2 日志相关的配置

.log4j2.xml

<Configuration status="WARN">
    <Properties>
        <Property name="LOG_HOME">./logsProperty>
    Properties>
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%level [%date{HH:mm:ss.SSS}][%thread][%class][%line]:%message%n"/>
        Console>

        <RollingRandomAccessFile name="infoLog" fileName="${LOG_HOME}/info.log"
                                 filePattern="${LOG_HOME}/info.%d{yyyy-MM-dd}.log.gz" immediateFlush="false" append="true">
            <PatternLayout pattern="[%X][%date{yyyy-MM-dd HH:mm:ss.SSS}][%thread][%level]:%message%n"/>
            <Filters>
                <ThresholdFilter level="error" onMatch="DENY" onMismatch="NEUTRAL"/>
                <ThresholdFilter level="warn" onMatch="DENY" onMismatch="NEUTRAL"/>
                <ThresholdFilter level="info" onMatch="ACCEPT" onMismatch="DENY"/>
                <ThresholdFilter level="debug" onMatch="ACCEPT" onMismatch="DENY"/>
            Filters>
            <Policies>
                <TimeBasedTriggeringPolicy interval="1" modulate="true"/>
            Policies>
        RollingRandomAccessFile>
        <RollingRandomAccessFile name="warnLog" fileName="${LOG_HOME}/warn.log"
                                 filePattern="${LOG_HOME}/warn.%d{yyyy-MM-dd}.log.gz" immediateFlush="false" append="true">
            <Filters>
                <ThresholdFilter level="error" onMatch="DENY" onMismatch="NEUTRAL"/>
                <ThresholdFilter level="warn" onMatch="ACCEPT" onMismatch="DENY"/>
            Filters>
            <PatternLayout pattern="[%X][%date{yyyy-MM-dd HH:mm:ss.SSS}][%thread][%level][%class][%line]:%message%n"/>
            <Policies>
                <TimeBasedTriggeringPolicy interval="1" modulate="true"/>
            Policies>
        RollingRandomAccessFile>
        <RollingRandomAccessFile name="errorLog" fileName="${LOG_HOME}/error.log"
                                 filePattern="${LOG_HOME}/error.%d{yyyy-MM-dd}.log.gz" immediateFlush="false" append="true">
            <Filters>
                <ThresholdFilter level="ERROR" onMatch="ACCEPT" onMismatch="DENY"/>
            Filters>
            <PatternLayout pattern="[%X][%date{yyyy-MM-dd HH:mm:ss.SSS}][%thread][%level][%class][%line]:%message%n"/>
            <Policies>
                <TimeBasedTriggeringPolicy interval="1" modulate="true"/>
            Policies>
        RollingRandomAccessFile>

    Appenders>

    <Loggers>

        
        <logger name="org.springframework" level="info" additivity="false">
            <appender-ref ref="infoLog"/>
            <appender-ref ref="warnLog"/>
            <appender-ref ref="errorLog"/>
        logger>

        
        <Root level="warn" includeLocation="true">
            <appender-ref ref="infoLog"/>
            <appender-ref ref="warnLog"/>
            <appender-ref ref="errorLog"/>
        Root>

    Loggers>

Configuration>

.log4j2.component.properties

# 设置全异步的打日志方式， 就不需要在命令行加 -Dlog4j2.contextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector 参数了
log4j2.contextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector
# size = 1024 * 1024
log4j2.asyncLoggerRingBufferSize=1048576
# discard not to block the queue
log4j2.asyncQueueFullPolicy=Discard
# 默认是在 INFO 级别去 discard
log4j2.discardThreshold=INFO

参考

1. csdn blog: java日志组件介绍（common-logging，log4j，slf4j，logback ）
2. 简书: 该让log4j退休了 - 论Java日志组件的选择
3. 网易lede: 日志工具现状调研
4. 网易lede: Log4j 2.x 日志升级的详细流程（针对各种混合使用Log4j 1.x，Logback，JCL,JUL等）
5. log4j2 runtime-dependencies: log4j2 相关 jar 及依赖关系
6. log4j2 async: Asynchronous Loggers
7. log4j2 performance: log4j2 performance
8. log4j2 garbagefree: garbagefree
9. lock-free by disruptor: lock-free data structure
10. log4j 配置文件: log4j2 configuration
11. log4j2异步注意事项
12. log4j2性能剖析
13. log4j2异步Logger