jvm异常分析

mychao

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java

jstack jmap

jvm查找问题常用工具jstack、jmap、btrace。

1. jstack常用命令：
    C:\Users\mychao>jstack -help
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

2. jstack -l 8724 使用实例见附图
3. jmap常用命令：
C:\Users\mychao>jmap
Usage:
    jmap [option] <pid>
        (to connect to running process)
    jmap [option] <executable <core>
        (to connect to a core file)
    jmap [option] [server_id@]<remote server IP or hostname>
        (to connect to remote debug server)

where <option> is one of:
    <none>               to print same info as Solaris pmap
    -heap                to print java heap summary
    -histo[:live]        to print histogram of java object heap; if the "live"
                         suboption is specified, only count live objects
    -permstat            to print permanent generation statistics
    -finalizerinfo       to print information on objects awaiting finalization
    -dump:<dump-options> to dump java heap in hprof binary format
                         dump-options:
                           live         dump only live objects; if not specified
,
                                        all objects in the heap are dumped.
                           format=b     binary format
                           file=<file> dump heap to <file>
                         Example: jmap -dump:live,format=b,file=heap.bin <pid>
    -F                   force. Use with -dump:<dump-options> <pid> or -histo
                         to force a heap dump or histogram when <pid> does not
                         respond. The "live" suboption is not supported
                         in this mode.
    -h | -help           to print this help message
    -J<flag>             to pass <flag> directly to the runtime system

4. jmap 查看当前jvm内存使用情况，包括年轻代、年老代、永久代，见附图