Je suis sûr que vous avez utilisé jstack pour générer des traces de pile et jmap pour obtenir des vidages de tas.
Mais dernièrement (?) Peut couvrir les deux avec juste jcmd.
Tout d'abord, exécutons jcmd sans arguments.
$ jcmd
62818 com.example.demo.DemoApplication
62819 jdk.jcmd/sun.tools.jcmd.JCmd
62810 org.apache.maven.wrapper.MavenWrapperMain spring-boot:run
De cette manière, le PID et la classe principale de l'application Java exécutée sur la machine sont répertoriés.
Ensuite, passons le PID à jcmd. Ici, passons le PID de DemoApplication.
$ jcmd 62818
62818:
The following commands are available:
Compiler.CodeHeap_Analytics
Compiler.codecache
Compiler.codelist
Compiler.directives_add
Compiler.directives_clear
Compiler.directives_print
Compiler.directives_remove
Compiler.queue
GC.class_histogram
GC.class_stats
GC.finalizer_info
GC.heap_dump
GC.heap_info
GC.run
GC.run_finalization
JFR.check
JFR.configure
JFR.dump
JFR.start
JFR.stop
JVMTI.agent_load
JVMTI.data_dump
ManagementAgent.start
ManagementAgent.start_local
ManagementAgent.status
ManagementAgent.stop
Thread.print
VM.class_hierarchy
VM.classloader_stats
VM.classloaders
VM.command_line
VM.dynlibs
VM.flags
VM.info
VM.log
VM.metaspace
VM.native_memory
VM.print_touched_methods
VM.set_flag
VM.stringtable
VM.symboltable
VM.system_properties
VM.systemdictionary
VM.uptime
VM.version
help
For more information about a specific command use 'help <command>'.
Voici une liste de commandes disponibles pour ce processus.
Sortons une trace de pile.
$ jcmd 62818 Thread.print
62818:
2019-12-04 08:49:43
Full thread dump OpenJDK 64-Bit Server VM (11.0.2+9 mixed mode):
(Omis)
"Common-Cleaner" #11 daemon prio=8 os_prio=31 cpu=1.60ms elapsed=263.23s tid=0x00007f8650010800 nid=0x5c03 in Object.wait() [0x000070000b852000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait([email protected]/Native Method)
- waiting on <0x000000060003bee0> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove([email protected]/ReferenceQueue.java:155)
- waiting to re-lock in wait() <0x000000060003bee0> (a java.lang.ref.ReferenceQueue$Lock)
at jdk.internal.ref.CleanerImpl.run([email protected]/CleanerImpl.java:148)
at java.lang.Thread.run([email protected]/Thread.java:834)
at jdk.internal.misc.InnocuousThread.run([email protected]/InnocuousThread.java:134)
"Catalina-utility-1" #15 prio=1 os_prio=31 cpu=36.80ms elapsed=257.29s tid=0x00007f864802a800 nid=0x7003 waiting on condition [0x000070000c77f000]
java.lang.Thread.State: WAITING (parking)
at jdk.internal.misc.Unsafe.park([email protected]/Native Method)
- parking to wait for <0x000000061c615798> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park([email protected]/LockSupport.java:194)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await([email protected]/AbstractQueuedSynchronizer.java:2081)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take([email protected]/ScheduledThreadPoolExecutor.java:1177)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take([email protected]/ScheduledThreadPoolExecutor.java:899)
at java.util.concurrent.ThreadPoolExecutor.getTask([email protected]/ThreadPoolExecutor.java:1054)
at java.util.concurrent.ThreadPoolExecutor.runWorker([email protected]/ThreadPoolExecutor.java:1114)
at java.util.concurrent.ThreadPoolExecutor$Worker.run([email protected]/ThreadPoolExecutor.java:628)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run([email protected]/Thread.java:834)
(Omis ci-dessous)
Obtenons un vidage de tas.
$ ls
$ jcmd 62818 GC.heap_dump `pwd`/demo.hprof
62818:
Heap dump file created
$ ls
demo.hprof
C'est facile parce que vous n'avez pas à vous souvenir de plusieurs commandes telles que jstack et jmap comme ça, il vous suffit de vous souvenir de jcmd.
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