1. Vm process status tool JPS
JPS, the JVM Process Status Tool, is used to list the Java virtual machine processes currently running.
JPS [-q] [-mlvv] []
The command has the following options:
-q: Outputs only the process number
-m: Displays the parameters passed to the main method
-l: displays the full class name of the main method, or the Jar path if it is run in Jar mode
-v: Displays the parameters passed to the JVM
2. Vm statistics monitoring tool Jstat
Jstat is a JVM Statistics Monitoring Tool used to monitor the running status of virtual machines.
Command format: jstat – [-t] [-h] [[]]
Common options of this command are as follows:
-class: monitors the number of classes loaded and unloaded and the time it takes to load a class
– GC: monitors the usage of each interval in the Java heap and the gc time
-gcutil: This option is similar to -gc, except that only the usage is displayed
-gccause: This option is similar to -gc, but it has a reason for the garbage collection
The meanings of the following fields in the output of this option:
S0: Survivor 0 usage
S1: Survivor 1 usage
E: Eden space usage
O: Old space usage
M: Metadata usage
CCS: Compressed class space capacity
YGC: Number of Cenozoic GC
YGCT: Total time of Cenozoic GC
FGC: the number of GC in the old age
FGCT: Total GC time in old age
GCT: indicates the total GC time
LGCC: Last GC cause
GCC: indicates the current GC cause
Java configuration information tool JINFO
Jinfo is Configuration Info for Java, which is used to view vm parameters.
Command format: jinfo [option], -sysprops Displays Java system properties. If no option is selected, the default configuration information of the specified process ID is displayed
4, memory image tool JMAP, very useful
Jmap, which stands for JVM Memory for Java, is used to export Memory snapshots of Java processes. The jMAP is used with the Memory snapshot analysis tool to locate Memory leaks.
Command format: jmap [option]
Main options:
-dump: [live,] format = b, file = filename: exports memory snapshots. The live option indicates that only live objects are exported. Note: This option causes SWT, so don’t use it
– finalizerInfo: displays objects waiting for the Finalizer thread to execute the Finalize method in the F-Queue Queue
-heap: Displays detailed Java heap information
-histo: displays statistics about objects in the Java heap
-f: Forcibly generates a dump snapshot when no response is received using -dump
Five, thread stack trace tool JStack
Jstack, which stands for Stack Trace for Java, is used to generate snapshots of vm threads at the current time.
Jstack -f [-m] [-l]
Options:
-l: Displays other information about locks
-m: Prints the stack in mixed mode, including C/C++ and Java
-f: Forcibly outputs stack information when there is no response
Java VisualVM, a visual monitoring tool
Java VisualVM is a visual performance monitoring tool of the JDK, which is generally used for debugging in the native development environment. You can view JVM parameters, system properties, thread health, and more. Can check http://docs.oracle.com/javase/8/docs/technotes/guides/visualvm/index.html for more information
A very useful performance monitoring tool for Java virtual machines