Java 17
Windows 11
-
发生问题
运行了一个 java程序，基于 Java 17 的。
在使用 jmap 查看堆内存分配时，出现了错误：
>jmap -heap 8400
Error: -heap option used
Cannot connect to core dump or remote debug server. Use jhsdb jmap instead |
提示使用 jhsdb jamp 替代。ben发布于博客园
jhsdb 帮助信息
>jhsdb --help
>jhsdb --help
clhsdb command line debugger
hsdb ui debugger
debugd --help to get more information
jstack --help to get more information
jmap --help to get more information
jinfo --help to get more information
jsnap --help to get more information |
注意，这里有 jmap、jstack、jinfo 等 子命令。
jhsdb jmap 帮助信息
>jhsdb jmap --helpben发布于博客园
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>jhsdb jmap --help
<no option> To print same info as Solaris pmap.
--heap To print java heap summary.
--binaryheap To dump java heap in hprof binary format.
--dumpfile <name> The name of the dump file. Only valid with --binaryheap.
--gz <1-9> The compression level for gzipped dump file. Only valid with --binaryheap.
--histo To print histogram of java object heap.
--clstats To print class loader statistics.
--finalizerinfo To print information on objects awaiting finalization.
--pid <pid> To attach to and operate on the given live process.
--core <corefile> To operate on the given core file.
--exe <executable for corefile>
--connect [<serverid>@]<host>[:registryport][/servername] To connect to a remote debug server (debugd).
The --core and --exe options must be set together to give the core
file, and associated executable, to operate on. They can use
absolute or relative paths.
The --pid option can be set to operate on a live process.
The --connect option can be set to connect to a debug server (debugd).
--core, --pid, and --connect are mutually exclusive.
Examples: jhsdb jmap --pid 1234
or jhsdb jmap --core ./core.1234 --exe ./myexe
or jhsdb jmap --connect serverid@debugserver:1234/servername
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ben发布于博客园
jhsdb jmap 查看堆信息
错误命令：没有 --pid
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>jhsdb jmap --heap 8400
SA agent option related exception occurred: You have to set --pid or --exe or --connect.
sun.jvm.hotspot.SAGetoptException: You have to set --pid or --exe or --connect.
at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.buildAttachArgs(SALauncher.java:178)
at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.runJMAP(SALauncher.java:340)
at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.main(SALauncher.java:500)
<no option> To print same info as Solaris pmap.
略
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ben发布于博客园
正确命令：
|
>jhsdb jmap --heap --pid 8400
Attaching to process ID 8400, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 17.0.10+13-LTS
using thread-local object allocation.
Garbage-First (G1) GC with 8 thread(s)
Heap Configuration:
MinHeapFreeRatio = 40
MaxHeapFreeRatio = 70
MaxHeapSize = 2118123520 (2020.0MB)
NewSize = 1363144 (1.2999954223632812MB)
MaxNewSize = 1270874112 (1212.0MB)
OldSize = 5452592 (5.1999969482421875MB)
NewRatio = 2
SurvivorRatio = 8
MetaspaceSize = 22020096 (21.0MB)
CompressedClassSpaceSize = 1073741824 (1024.0MB)
MaxMetaspaceSize = 17592186044415 MB
G1HeapRegionSize = 1048576 (1.0MB)
Heap Usage:
G1 Heap:
regions = 2020
capacity = 2118123520 (2020.0MB)
used = 75820528 (72.30809020996094MB)
free = 2042302992 (1947.691909790039MB)
3.5796084262356898% used
G1 Young Generation:
Eden Space:
regions = 45
capacity = 54525952 (52.0MB)
used = 47185920 (45.0MB)
free = 7340032 (7.0MB)
86.53846153846153% used
Survivor Space:
regions = 3
capacity = 4194304 (4.0MB)
used = 3507696 (3.3451995849609375MB)
free = 686608 (0.6548004150390625MB)
83.62998962402344% used
G1 Old Generation:
regions = 25
capacity = 38797312 (37.0MB)
used = 25126912 (23.962890625MB)
free = 13670400 (13.037109375MB)
64.76456925675676% used
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jhsdb是什么？
“JHSDB，即 Java HotSpot Serviceability Debugger，是OpenJDK提供的一款强大的进程外调试工具。”
“JHSDB虽然是JDK 9中才正式提供，但之前已经以sa-jdi.jar包里面的HSDB（可视化工 具）和CLHSDB（命令行工具）的形式存在了很长一段时间。它们两个都是JDK的正式成员，随着JDK一同发布，无须独立下载，使用也是完全免费的。”
---end---
参考资料：
1、深入探索OpenJDK的JHSDB工具：Java调试的新境界
https://developer.baidu.com/article/detail.html?id=3316553
作者：菠萝爱吃肉
2024.04.15 15:09
2、
ben发布于博客园
ben发布于博客园
