还在用 Log4j ？快用 Log4j2，性能太猛了！

待我称王封你为后i 2022-09-10 15:14 87阅读 0赞

**环境**

jdk：1.7.0\_79

cpu：[i5-4570@3.20GHz][i5-4570_3.20GHz] 4核

eclipse：3.7

操作系统：win7

**准备**

**1.log4j:1.7.21**

**log4j.xml**

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
    <log4j:configuration xmlns:log4j='http://jakarta.apache.org/log4j/'>
    
        <appender name="myConsole" class="org.apache.log4j.ConsoleAppender">
            <layout class="org.apache.log4j.PatternLayout">
                <param name="ConversionPattern" value="[%d{dd HH:mm:ss,SSS\} %-5p] [%t] %c{2\} - %m%n" />
            </layout>
    
            
            <filter class="org.apache.log4j.varia.LevelRangeFilter">
                <param name="levelMin" value="debug" />
                <param name="levelMax" value="warn" />
                <param name="AcceptOnMatch" value="true" />
            </filter>
        </appender>
    
        <appender name="myFile" class="org.apache.log4j.DailyRollingFileAppender">
            <param name="File" value="log4jTest.log" />
            <param name="Append" value="true" />
            <param name="DatePattern" value="'.'yyyy-MM-dd'.log'" />
            <layout class="org.apache.log4j.PatternLayout">
                <param name="ConversionPattern" value="[%t] - %m%n" />
            </layout>
        </appender>
    
        <appender name="async_file" class="org.apache.log4j.AsyncAppender">
            <param name="BufferSize" value="32" />
            <appender-ref ref="myFile" />
        </appender>
    
        <logger name="org.logTest" additivity="false">
            <level value="info" />
            <appender-ref ref="async_file" /> 
        </logger>
    
    </log4j:configuration>

**2.logback:1.1.7**

<dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.1.7</version>
    </dependency>

**logback.xml**

<configuration>
        <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
            
            <encoder>
                <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
                </pattern>
            </encoder>
        </appender>
    
        <appender name="FILE" class="ch.qos.logback.core.FileAppender">
            <file>testFile.log</file>
            <append>true</append>
            <encoder>
                <pattern>[%t] - %m%n
                </pattern>
            </encoder>
        </appender>
    
        
        <appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
            <discardingThreshold>0</discardingThreshold>
            <appender-ref ref="FILE" />
        </appender>
    
        <logger name="org.logTest" level="INFO"
            additivity="false">
            <appender-ref ref="ASYNC" />  
        </logger>
    
        <root level="ERROR">
            <appender-ref ref="STDOUT" />
        </root>
    </configuration>

**3.log4j2:2.6.2**

<dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.6.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-slf4j-impl</artifactId>
        <version>2.6.2</version>
    </dependency>
    <dependency>
        <groupId>com.lmax</groupId>
        <artifactId>disruptor</artifactId>
        <version>3.3.4</version>
    </dependency>

**log4j2.xml**

<?xml version="1.0" encoding="UTF-8"?>
    
    <configuration status="warn">
    
        <appenders>
             <console name="Console" target="SYSTEM_OUT">
                <PatternLayout pattern="[%d{HH:mm:ss:SSS}] [%p] - %l - %m%n" />
            </console>
    
            <RollingFile name="RollingFileInfo" fileName="info.log"
                filePattern="${sys:user.home}/logs/hpaasvc/$${date:yyyy-MM}/info-%d{yyyy-MM-dd}-%i.log">
                <Filters>
                    <ThresholdFilter level="INFO" />
                    <ThresholdFilter level="WARN" onMatch="DENY"
                        onMismatch="NEUTRAL" />
                </Filters>
                <PatternLayout pattern="[%t] - %m%n" />
                <Policies>
                    <TimeBasedTriggeringPolicy />
                    <SizeBasedTriggeringPolicy size="100 MB" />
                </Policies>
            </RollingFile>
    
            <RandomAccessFile name="RandomAccessFile" fileName="asyncWithLocation.log"
                immediateFlush="false" append="true">
                <PatternLayout>
                    <Pattern>[%t] - %m%n</Pattern>
                </PatternLayout>
            </RandomAccessFile>
    
        </appenders>
    
        <loggers>
            
            <Root level="info" includeLocation="true">
                <AppenderRef ref="RollingFileInfo" />
            </Root>
        </loggers>
    
    </configuration>

**测试**

准备50条线程同时记录1000000条数据，然后统计时间，详细代码如下：

import java.util.concurrent.CountDownLatch;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    public class App {
        private static Logger log = LoggerFactory.getLogger(App.class);
    
        public static void main(String[] args) throws InterruptedException {
            int messageSize = 1000000;
            int threadSize = 50;
            final int everySize = messageSize / threadSize;
    
            final CountDownLatch cdl = new CountDownLatch(threadSize);
            long startTime = System.currentTimeMillis();
            for (int ts = 0; ts < threadSize; ts++) {
                new Thread(new Runnable() {
    
                    @Override
                    public void run() {
                        for (int es = 0; es < everySize; es++) {
                            log.info("======info");
                        }
                        cdl.countDown();
                    }
                }).start();
            }
    
            cdl.await();
            long endTime = System.currentTimeMillis();
            System.out.println("log4j1:messageSize = " + messageSize
                    + ",threadSize = " + threadSize + ",costTime = "
                    + (endTime - startTime) + "ms");
        }
    }

log4j1和logback的同步和异步分别修改为对应的appender就行了

log4j2的异步方式提供了2中模式：

**1.全局开启**

设置Log4jContextSelector系统属性为： org.apache.logging.log4j.core.async.AsyncLoggerContextSelector

System.setProperty("Log4jContextSelector", "org.apache.logging.log4j.core.async.AsyncLoggerContextSelector");

**2.混合同步异步模式**

不需要设置Log4jContextSelector，但是需要使用AsyncLogger标签

更多详细参考官方文档：[http://logging.apache.org/log4j/2.x/manual/async.html\#AllAsync][http_logging.apache.org_log4j_2.x_manual_async.html_AllAsync]

**结果** 分别测试完以后统计成表格如下：

![20210909151718211.png][]

log4j2的异步模式表现了绝对的性能优势，优势主要得益于Disruptor框架的使用

LMAX Disruptor technology. Asynchronous Loggers internally use the Disruptor, a lock-free inter-thread communication library, instead of queues, resulting in higher throughput and lower latency.

一个无锁的线程间通信库代替了原来的队列

更多Disruptor ：

[http://developer.51cto.com/art/201306/399370.htm][http_developer.51cto.com_art_201306_399370.htm]

[http://ifeve.com/disruptor/][http_ifeve.com_disruptor]

来源：[https://my.oschina.net/OutOfMemory/blog/789267][https_my.oschina.net_OutOfMemory_blog_789267]

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[i5-4570_3.20GHz]: mailto:i5-4570@3.20GHz
[http_logging.apache.org_log4j_2.x_manual_async.html_AllAsync]: http://logging.apache.org/log4j/2.x/manual/async.html#AllAsync
[20210909151718211.png]: /images/20220829/0df4fb6bf88843e280573024d047e2d3.png
[http_developer.51cto.com_art_201306_399370.htm]: http://developer.51cto.com/art/201306/399370.htm
[http_ifeve.com_disruptor]: http://ifeve.com/disruptor/
[https_my.oschina.net_OutOfMemory_blog_789267]: https://my.oschina.net/OutOfMemory/blog/789267
[1_000_ _ Java_2021]: https://www.javastack.cn/mst/
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[Java _ xx _ null]: https://www.javastack.cn/article/2021/intellij-idea-ligatures-settings/
[Spring Boot 2.5]: https://www.javastack.cn/article/2021/spring-boot-2.5-released/
[Java]: http://www.javastack.cn/article/2020/alibaba-release-java-develop-rules-songshan/