Monitoring and troubleshooting tools in the JDK -03 (jstat)

JSTAT:JVM Statistics Monitoring Tool

The Jstat command monitors various runtime state information for the JVM virtual machine, including memory status, garbage collection, loading of classes, and so on.

Jstat command format: jstat [option Vmid [interval] [count]]

Jstat command Examples

Command: JSTAT-GC 1203 500 3

Command explanation: Check the status of garbage collection with process ID 1203 every 500 milliseconds, query 3 times

Command options

Options	Role
-class	Output class load, unload quantity, and time consumed by class load
-gc	Monitor Java heap status, including edge Zone, Survivor Zone, old age, permanent generation capacity, used space, GC time, etc.
-gcnew	Monitor New generation GC status
-gcold	Monitor the status of GC in the old age
-gccause	Basically the same as-GC, but output causes the last GC to produce
-compiler	Output JIT compiler compiled methods, time-consuming and other information

Monitoring and troubleshooting tools in the JDK -03 (jstat)