【Java命令二】jhat
Java  /  管理员 发布于 3年前   295
jhat用于分析使用jmap dump的文件,,可以将堆中的对象以html的形式显示出来,包括对象的数量,大小等等,并支持对象查询语言。 jhat默认开启监听端口7000的HTTP服务,jhat是Java Heap Analysis Tool的缩写
1. 用法:
[hadoop@hadoop bin]$ jhat -helpUsage: jhat [-stack <bool>] [-refs <bool>] [-port <port>] [-baseline <file>] [-debug <int>] [-version] [-h|-help] <file>-J<flag> Pass <flag> directly to the runtime system. For example, -J-mx512m to use a maximum heap size of 512MB-stack false: Turn off tracking object allocation call stack.-refs false: Turn off tracking of references to objects-port <port>: Set the port for the HTTP server. Defaults to 7000-exclude <file>: Specify a file that lists data members that should be excluded from the reachableFrom query.-baseline <file>: Specify a baseline object dump. Objects in both heap dumps with the same ID and same class will be marked as not being "new".-debug <int>: Set debug level. 0: No debug output 1: Debug hprof file parsing 2: Debug hprof file parsing, no server-version Report version number-h|-help Print this help and exit<file> The file to readFor a dump file that contains multiple heap dumps,you may specify which dump in the fileby appending "#<number>" to the file name, i.e. "foo.hprof#3".All boolean options default to "true"
2. 产生堆内存dump文件
[hadoop@hadoop bin]$ jmap -dump:file=dump.bin.002 1819Dumping heap to /home/hadoop/software/jdk1.7.0_67/bin/dump.bin.002 ...Heap dump file created
3. 分析堆内存dump文件
提示找到1040038个对象
[hadoop@hadoop bin]$ jhat dump.bin.002 Reading from dump.bin.002...Dump file created Fri Feb 27 07:53:21 EST 2015Snapshot read, resolving...Resolving 1040038 objects...Chasing references, expect 208 dots................................................................................................................................................................................................................Eliminating duplicate references................................................................................................................................................................................................................Snapshot resolved.Started HTTP server on port 7000Server is ready.
4. UI上查看对象内存使用情况:
在首页底下有如下连接
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