本文的工具环境是 1.8.0_191-8u191
1.jinfo
Usage:
jinfo [option] <pid>
(to connect to running process)
jinfo [option] <executable <core>
(to connect to a core file)
jinfo [option] [server_id@]<remote server IP or hostname>
(to connect to remote debug server)
where <option> is one of:
-flag <name> to print the value of the named VM flag
-flag [+|-]<name> to enable or disable the named VM flag
-flag <name>=<value> to set the named VM flag to the given value
-flags to print VM flags
-sysprops to print Java system properties
<no option> to print both of the above
-h | -help to print this help message
jinfo -flags pid 查看全部启动参数
jinfo -flags 13874
Attaching to process ID 13874, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.191-b12
Non-default VM flags: -XX:CICompilerCount=3 -XX:+IgnoreUnrecognizedVMOptions -XX:InitialHeapSize=163577856 -XX:MaxHeapSize=2606759936 -XX:MaxNewSize=868745216 -XX:MinHeapDeltaBytes=524288 -XX:NewSize=54525952 -XX:OldSize=109051904 -XX:+PrintHeapAtGC -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC
Command line: -Xlog:gc* -Xlog:safepoint -XX:+IgnoreUnrecognizedVMOptions -XX:+PrintHeapAtGC -Xlog:gc:/home/tmp/heap_trace.txt -Djava.security.egd=file:/dev/./urandom
其它用法
jinfo -sysprops pid 查看系统参数
jinfo -flag +/- key [value] pid 开启/关闭某个参数
2. jstack
jstack主要用来追踪Java的堆栈信息。
- 针对活着的进程做本地的或远程的线程dump；
- 针对core文件做线程dump。
Usage:
jstack [-l] <pid>
(to connect to running process)
jstack -F [-m] [-l] <pid>
(to connect to a hung process)
jstack [-m] [-l] <executable> <core>
(to connect to a core file)
jstack [-m] [-l] [server_id@]<remote server IP or hostname>
(to connect to a remote debug server)
Options:
-F to force a thread dump. Use when jstack <pid> does not respond (process is hung)
-m to print both java and native frames (mixed mode)
-l long listing. Prints additional information about locks
-h or -help to print this help message
- -l 长列表. 打印关于锁的附加信息,例如属于java.util.concurrent 的 ownable synchronizers列表.
- -F 当
jstack [-l] pid没有相应的时候强制打印栈信息 - -m 打印java和native c/c++框架的所有栈信息.
