使用jmap -heap命令查看堆的详细信息报错
Caused by: java.lang.RuntimeException: unknown CollectedHeap type : class sun.jvm.hotspot.gc_interface.CollectedHeap
[root@bangbet-java ~]# jmap -heap27822Attaching to process ID 27822, pleasewait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.222-b10
using thread-localobject allocation.
Parallel GC with 4 thread(s)
Heap Configuration:
MinHeapFreeRatio =0 MaxHeapFreeRatio =100 MaxHeapSize =1073741824(1024.0MB)
NewSize =536870912(512.0MB)
MaxNewSize =536870912(512.0MB)
OldSize =536870912(512.0MB)
NewRatio =2 SurvivorRatio =8 MetaspaceSize =21807104(20.796875MB)
CompressedClassSpaceSize =1073741824(1024.0MB)
MaxMetaspaceSize =17592186044415 MB
G1HeapRegionSize =0(0.0MB)
Heap Usage:
Exception inthread"main" java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.tools.jmap.JMap.runTool(JMap.java:201)
at sun.tools.jmap.JMap.main(JMap.java:130)
Caused by: java.lang.RuntimeException: unknown CollectedHeap type : class sun.jvm.hotspot.gc_interface.CollectedHeap
at sun.jvm.hotspot.tools.HeapSummary.run(HeapSummary.java:157)
at sun.jvm.hotspot.tools.Tool.startInternal(Tool.java:260)
at sun.jvm.hotspot.tools.Tool.start(Tool.java:223)
at sun.jvm.hotspot.tools.Tool.execute(Tool.java:118)
at sun.jvm.hotspot.tools.HeapSummary.main(HeapSummary.java:50)
... 6more
奇怪，在本地是没问题的，在linux上却出现这种情况
查看了下jdk版本，都是1.8，没啥问题呀
本地是HotSpot
线上是OpenJDK
最终原因
这里-heap参数会调用用到了sun.jvm下的debug包，而默认openJDK的安装中不包含！
解决方式
下载并安装一个java-openjdk-debug插件！而且需要和openjdk小版本也一致！！！
安装debuginfo
去网站http://debuginfo.centos.org/7/x86_64里面找匹配当前的openjdk的版本，小版本号也要匹配上。
然后使用wget命令下载
wgethttp://debuginfo.centos.org/7/x86_64/java-1.8.0-openjdk-debuginfo-1.8.0.222.b10-0.el7_6.x86_64.rpm
使用rpm命令安装
rpm -ivh java-1.8.0-openjdk-debuginfo-1.8.0.222.b10-0.el7_6.x86_64.rpm
查看是否安装了debuginfo
[root@bangbet-java ~]# rpm -qa|grep debuginfo
java-1.8.0-openjdk-debuginfo-1.8.0.222.b10-0.el7_6.x86_64
再次查询
[root@bangbet-java ~]# jmap -heap27968Attaching to process ID 27968, pleasewait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.222-b10
using thread-localobject allocation.
Parallel GC with 4 thread(s)
Heap Configuration:
MinHeapFreeRatio =0 MaxHeapFreeRatio =100 MaxHeapSize =2147483648(2048.0MB)
NewSize =1073741824(1024.0MB)
MaxNewSize =1073741824(1024.0MB)
OldSize =1073741824(1024.0MB)
NewRatio =2 SurvivorRatio =8 MetaspaceSize =21807104(20.796875MB)
CompressedClassSpaceSize =1073741824(1024.0MB)
MaxMetaspaceSize =17592186044415 MB
G1HeapRegionSize =0(0.0MB)
Heap Usage:
PS Young Generation
Eden Space:
capacity =1054867456(1006.0MB)
used =521443544(497.28731536865234MB)
free=533423912(508.71268463134766MB)
49.43213870463741% used
From Space:
capacity =8388608(8.0MB)
used =8377312(7.989227294921875MB)
free=11296(0.010772705078125MB)
99.86534118652344% used
To Space:
capacity =9437184(9.0MB)
used =0(0.0MB)
free=9437184(9.0MB)
0.0% used
PS Old Generation
capacity =1073741824(1024.0MB)
used =334280072(318.79431915283203MB)
free=739461752(705.205680847168MB)
31.132257729768753% used35880interned Strings occupying4018400bytes.
ok，解决完毕！
遇到的版本问题
我的jdk版本是1.8.0_222-b10，在http://debuginfo.centos.org/7/x86_64找到两个
先下载了个最新的发现并不好使，之后卸载重新下载另一个
rpm卸载
rpm -e --nodeps java-1.8.0-openjdk-debuginfo-1:1.8.0.222.b10-1.el7_7.x86_64
之后重新安装即可
