还在用 Log4j ？快用 Log4j2，性能太猛了！
环境
jdk：1.7.0_79
cpu：i5-4570@3.20GHz 4核
eclipse：3.7
操作系统：win7
准备
1.log4j:1.7.21
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.21</version>
</dependency>
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>
<!--过滤器设置输出的级别 -->
<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" /> <!-- 同步:FILE 异步: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 默认配置为PatternLayoutEncoder -->
<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>
<!-- 异步输出 -->
<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" /> <!-- 同步:FILE 异步: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"?>
<!--设置log4j2的自身log级别为warn -->
<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>
<!-- <AsyncLogger name="asynLogger" level="trace"
includeLocation="true">
<AppenderRef ref="RandomAccessFile" />
</AsyncLogger> -->
<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
结果
分别测试完以后统计成表格如下：
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
来源：https://my.oschina.net/OutOfMemory/blog/789267
近期热文推荐：
1.1,000+ 道 Java面试题及答案整理(2021最新版)
2.别在再满屏的 if/ else 了，试试策略模式，真香！！
3.卧槽！Java 中的 xx ≠ null 是什么新语法？
4.Spring Boot 2.5 重磅发布，黑暗模式太炸了！
觉得不错，别忘了随手点赞+转发哦！
