Java –什么是-Xms和-Xmx参数？

在Java中， -Xms设置初始Java堆大小，而-Xmx设置最大Java堆大小。

1.一些java -Xms -Xmx示例：

# Start with 128MB of memory, and allow the Java process to use up to 1024MB of memory. 
java -Xms128m -Xmx1024m

# Start with 256MB of memory, and allow the Java process to use up to 4G (4096MB) of memory.
java -Xms256m -Xmx4g

2.默认的初始和最大Java堆大小是根据这种人体工程学算法分配的，还请阅读本文– 查找Java堆内存大小

3.如果Java进程超出了-Xmx最大Java堆大小，则将引发流行的java.lang.OutOfMemoryError 。

4.对于其他选项，请运行此java -X

> java -X

    -Xbatch           disable background compilation
    -Xbootclasspath/a:<directories and zip/jar files separated by ;>
                      append to end of bootstrap class path
    -Xcheck:jni       perform additional checks for JNI functions
    -Xcomp            forces compilation of methods on first invocation
    -Xdebug           provided for backward compatibility
    -Xdiag            show additional diagnostic messages
    -Xfuture          enable strictest checks, anticipating future default
    -Xint             interpreted mode execution only
    -Xinternalversion
                      displays more detailed JVM version information than the
                      -version option
    -Xloggc:<file>    log GC status to a file with time stamps
    -Xmixed           mixed mode execution (default)
    -Xmn<size>        sets the initial and maximum size (in bytes) of the heap
                      for the young generation (nursery)
    -Xms<size>        set initial Java heap size
    -Xmx<size>        set maximum Java heap size
    -Xnoclassgc       disable class garbage collection
    -Xrs              reduce use of OS signals by Java/VM (see documentation)
    -Xshare:auto      use shared class data if possible (default)
    -Xshare:off       do not attempt to use shared class data
    -Xshare:on        require using shared class data, otherwise fail.
    -XshowSettings    show all settings and continue
    -XshowSettings:all
                      show all settings and continue
    -XshowSettings:locale
                      show all locale related settings and continue
    -XshowSettings:properties
                      show all property settings and continue
    -XshowSettings:vm
                      show all vm related settings and continue
    -XshowSettings:system
                      (Linux Only) show host system or container
                      configuration and continue
    -Xss<size>        set java thread stack size
    -Xverify          sets the mode of the bytecode verifier