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https://blog.souche.com/logback-log4j-log4j2shi-ce/

https://blog.csdn.net/weixin_43495390/article/details/86533482

1、提交无限多个线程，怎么构造OOM

2、元数据区溢出？通过动态代理创建无限多个类

3、元数据区溢出？常量池？这个常量池是啥呢?

方法区移至Metaspace，字符串常量移至Java Heap

-Xss256k
-Xms32m
-Xmx256m
-XX:MetaspaceSize=32m
-XX:MaxMetaspaceSize=128m
-XX:+DisableExplicitGC
-XX:+UseConcMarkSweepGC
-XX:+UseCMSInitiatingOccupancyOnly
-XX:CMSInitiatingOccupancyFraction=62
-XX:-HeapDumpOnOutOfMemoryError
-Dsun.zip.disableMemoryMapping=true

jstat -gcutil 302735 1000 5 --- 某个进程GC状况，百分比格式; 采集间隔1000ms, 共采集5次
jmap -dump:file=./test.prof 302735 --- 生成某个进程的堆内存转储快照
-XX:+PrintGCDetails --- 启动后打印GC详细信息
jconsole、virtualVM、Eclipse Memory Analyzer

https://blog.csdn.net/laomo_bible/article/details/83112622

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<dependencies>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.30</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
        <version>2.13.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.13.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-slf4j-impl</artifactId>
        <version>2.13.2</version>
    </dependency>
</dependencies>

<?xml version="1.0" encoding="UTF-8" ?>
<Configuration xmlns="http://logging.apache.org/log4j/2.0/config">
    <Properties>
        <Property name="log.pattern">%d{YYYY-MM-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n%n</Property>
    </Properties>
    <Appenders>
        <Console name="console" target="SYSTEM_OUT">
            <PatternLayout pattern="${log.pattern}"/>
        </Console>
        <RollingFile name="error" bufferedIO="true" fileName="log/error.log" filePattern="logs/error-%d{yyyy-MM-dd HH}.log">
            <PatternLayout pattern="${log.pattern}"/>
            <Policies>
                <SizeBasedTriggeringPolicy size="500MB"/>
            </Policies>
        </RollingFile>
    </Appenders>
    <Loggers>
        <Root level="info">
            <AppenderRef ref="console" />

            <AppenderRef ref="error" level="error" />
        </Root>
    </Loggers>
</Configuration>