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开发规范之log4j异步打印日志

本文概览 :选择打印日志方案为: 使用log4j,并且使用AsyncLogger 异步打印。

1 日志框架方案

1 、项目中选择日志框架是 log4j2

因为目前常遇见的日志框架有 log4j logback log4j2 logback 是为了优化 log4j 而生的, log4j2 又在 logback 基础上做了优化。所以日志框架选型顺序为: log4j2 > logback > log4j 。这三个都是同一个作者所写。

2log4j2 配置为异步方式

使用同步方式,在高并发情况下会对接口性能有影响,所以使用异步方式。异步日志有 AsyncAppenderAsyncLogger 两种方式, 建议使用 AsyncLogger 方式 。AsyncLogger是log4j2新增的,使用LMAX Disruptor来实现高吞吐量;Async Appender在log4j1的时候就已经有了。

2 AsyncLogger 配置异步日志

1 maven 配置

<!--配置4j-->
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-api</artifactId>
            <version>2.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-slf4j-impl</artifactId>
            <version>2.3</version>
        </dependency>
        <dependency>
            <groupId>com.lmax</groupId>
            <artifactId>disruptor</artifactId>
            <version>3.4.2</version>
        </dependency>

2、log4j2.xml配置

<?xml version="1.0" encoding="UTF-8"?>
 
<!-- No need to set system property "Log4jContextSelector" to any value
     when using <asyncLogger> or <asyncRoot>. -->
 
<Configuration status="WARN">
 
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout>
                <Pattern>%d %p %class{1.} [%t] %location %m %ex%n</Pattern>
            </PatternLayout>
        </Console>
        <!-- Async Loggers will auto-flush in batches, so switch off immediateFlush. -->
        <RandomAccessFile name="RandomAccessFile" fileName="./sync.log"
                          immediateFlush="false" append="false">
            <PatternLayout>
                <Pattern>%d %p %class{1.} [%t] %location %m %ex%n</Pattern>
            </PatternLayout>
        </RandomAccessFile>
    </Appenders>
    <Loggers>
        <!-- pattern layout actually uses location, so we need to include it -->
        <AsyncLogger name="com.test" level="info" includeLocation="true">
            <AppenderRef ref="RandomAccessFile"/>
            <AppenderRef ref="Console"/>
        </AsyncLogger>
        <AsyncRoot level="info" includeLocation="true">
            <AppenderRef ref="RandomAccessFile"/>
        </AsyncRoot>
    </Loggers>
</Configuration>

3 相关问题

3.1 log4j2和logback冲突问题

一个项目中只能使用log4j2或者logback。假设在项目中使用了log4j2,此时使用外部依赖jar时候,发现外部依赖使用了logbakc,如何解决这个问题? 将外部依赖的logback的包通过exclude排除掉

参考文献

Log4j2中的同步日志与异步日志 https://www.cnblogs.com/yeyang/p/7944906.html

高性能队列——Disruptor https://tech.meituan.com/2016/11/18/disruptor.html

Asynchronous Loggers for Low-Latency Logging https://logging.apache.org/log4j/log4j-2.3/manual/async.html

原文  http://www.heartthinkdo.com/?p=3057
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