Arthas command parsing (jvm/thread/stack/heapdump)

Arthas is an open source Java diagnostic tool from Alibaba, Arthas supports JDK 6+, supports Linux/Mac/Windows, adopts command-line interactive mode, and provides rich Tab auto-completion functions to further facilitate problem location and diagnosis.

Arthas 3.0 uses the OGNL expression evaluation library, see OGNL expression official website

Common commands

jvm

View current JVM information

THREAD related

• COUNT: The number of currently active threads in the JVM
• DAEMON-COUNT: The number of daemon threads currently active in the JVM
• PEAK-COUNT: Maximum number of threads ever alive since JVM startup
• STARTED-COUNT: The total number of threads started since the JVM started
• DEADLOCK-COUNT: The number of threads currently deadlocked by the JVM

thread

View current thread information, view thread stack

parameter name	Parameter description
id	thread id
[n:]	Specify the busiest top N threads and print the stack
[b]	Find out which thread is currently blocking other threads
[i ]	Specify the sampling interval of cpu usage statistics, in milliseconds, the default value is 200
[–all]	Show all matching threads

How is cpu usage calculated?
The cpu usage rate here is similar to the thread %CPU of the linux command top -H -p . During a sampling interval, each thread in the current JVMThe ratio of incremental cpu time to sampling interval time.

$ threadThreads Total: 33, NEW: 0, RUNNABLE: 9, BLOCKED: 0, WAITING: 3, TIMED_WAITING: 4, TERMINATED: 0, Internal threads: 17ID NAME GROUP PRIORITY STATE %CPU DELTA_TIME TIME INTERRUPT DAEMON-1 C2 CompilerThread0 - -1 - 5.06 0.010 0:0.973 false true

stack

Output the calling path where the current method is called

parameter name	Parameter description
class-pattern	class name expression match
method-pattern	method name expression match
condition-express	conditional expression
[E]	Enable regular expression matching, default is wildcard matching
[n:]	execution limit

Filter by execution time

$ stack demo.MathGame primeFactors '#cost>5' -n 2

heapdump

dump java heap, similar to the heap dump function of the jmap command.

dump to the specified file

[[email protected]]$ heapdump /tmp/dump.hprofDumping heap to /tmp/dump.hprof...Heap dump file created

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References:

1. Arthas User Documentation
2. When DUBBO meets Arthas - Practice of Troubleshooting
3. Arthas expression core variables