jmap -heap 8
时间: 2024-06-19 14:03:10 浏览: 101
jmap是Java虚拟机自带的一款诊断工具,可以生成堆转储快照,查看Java堆内存的详细信息,如对象实例数量、对象大小、类元数据等等。而使用jmap -heap命令可以生成Java堆内存转储快照,并显示Java堆内存使用情况的概要信息。其中,8代表的是Java进程的进程ID或者Java应用程序的主类名,如果是进程ID,则可以通过jps命令查看到。如果是主类名,则需要在启动Java应用程序时加上参数“-Dcom.sun.management.jmxremote”以开启JMX远程管理功能。
以下是jmap -heap 8命令的输出示例:
```
Attaching to process ID 8, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.162-b12
using thread-local object allocation.
Parallel GC with 2 thread(s)
Heap Configuration:
MinHeapFreeRatio = 0
MaxHeapFreeRatio = 100
MaxHeapSize = 2147483648 (2048.0MB)
NewSize = 1363144 (1.2999954223632812MB)
MaxNewSize = 17592186044415 MB
OldSize = 5452592 (5.1999969482421875MB)
NewRatio = 2
SurvivorRatio = 8
MetaspaceSize = 21807104 (20.796875MB)
CompressedClassSpaceSize = 1073741824 (1024.0MB)
MaxMetaspaceSize = 17592186044415 MB
G1HeapRegionSize = 1048576 (1.0MB)
Heap Usage:
PS Young Generation
Eden Space:
capacity = 268435456 (256.0MB)
used = 37594304 (35.857704162597656MB)
free = 230841152 (220.14229583740234MB)
13.996054887771606% used
From Space:
capacity = 17825792 (17.0MB)
used = 1389360 (1.32489013671875MB)
free = 16436432 (15.67510986328125MB)
7.78817692279646% used
To Space:
capacity = 17825792 (17.0MB)
used = 0 (0.0MB)
free = 17825792 (17.0MB)
0.0% used
PS Old Generation
capacity = 536870912 (512.0MB)
used = 47535704 (45.337806701660156MB)
free = 489335208 (466.66219329833984MB)
8.85840892791748% used
23891 interned Strings occupying 2404488 bytes.
```