cjmx

cjmx is a command line JMX client intended to be used when graphical tools (e.g., JConsole, VisualVM) are unavailable. Additionally, cjmx intends to be useful in scripting environments.

Building

To build, run ./sbt publish-local. This will build target/cjmx.jar and install a copy to your local ivy cache.

Usage

Launching cjmx is done via:

java -cp $JAVA_HOME/lib/tools.jar:cjmx.jar cjmx.Main [PID]

Or, if tools.jar is on the classpath already (e.g., Apple JVM):

java -jar cjmx.jar [PID]

If a PID is specified on the command line, cjmx will attempt to connect to the local JVM with that PID; otherwise, cjmx starts in a disconnected state.

Once cjmx starts, a prompt will appear. Cjmx makes heavy use of tab completion, enabling exploration of the MBean tree. For example:

java -jar cjmx.jar 1234
> <TAB>
disconnect   exit         describe      names        select
> names 'java.<TAB>
java.lang:           java.util.logging:
> describe -d 'java.lang:type=
*                  <value>            ClassLoading       Compilation
GarbageCollector   Memory             MemoryManager      MemoryPool
OperatingSystem    Runtime            Threading
> names 'java.lang:type=*'
java.lang:type=ClassLoading
java.lang:type=Compilation
java.lang:type=Memory
java.lang:type=OperatingSystem
java.lang:type=Runtime
java.lang:type=Threading
> describe -d 'java.lang:type=Memory'
Object name: java.lang:type=Memory
----------------------------------
Description: Information on the management interface of the MBean

Attributes:
  Verbose: boolean
    Description: Verbose
  ObjectPendingFinalizationCount: int
    Description: ObjectPendingFinalizationCount
  HeapMemoryUsage: CompositeData
    Description: HeapMemoryUsage
  NonHeapMemoryUsage: CompositeData
    Description: NonHeapMemoryUsage

Operations:
  gc(): void
    Description: gc

Notifications:
  javax.management.Notification
    Description: MEMORY NOTIFICATION
    Notification types:
      java.management.memory.threshold.exceeded
      java.management.memory.collection.threshold.exceeded

> mbeans 'java.lang:type=Memory' select *
java.lang:type=Memory
---------------------
  Verbose: false
  ObjectPendingFinalizationCount: 0
  HeapMemoryUsage:
    committed: 110432256
    init: 0
    max: 2130051072
    used: 63307880
  NonHeapMemoryUsage:
    committed: 140849152
    init: 24317952
    max: 318767104
    used: 121815008

Alternatively, cjmx can run a series of commands and then terminate. This is done by specifying each command as a program argument. For example:

java -jar cjmx.jar 1234 "describe 'java.lang:type=Memory'" "mbeans 'java.lang:type=Memory' select *"
Object name: java.lang:type=Memory
----------------------------------
Description: Information on the management interface of the MBean

Attributes:
  Verbose: boolean
  ObjectPendingFinalizationCount: int
  HeapMemoryUsage: CompositeData
  NonHeapMemoryUsage: CompositeData

Operations:
  gc(): void

Notifications:
  javax.management.Notification

java.lang:type=Memory
---------------------
  Verbose: false
  ObjectPendingFinalizationCount: 0
  HeapMemoryUsage:
    committed: 110432256
    init: 0
    max: 2130051072
    used: 76943832
  NonHeapMemoryUsage:
    committed: 140980224
    init: 24317952
    max: 318767104
    used: 122049448

All commands have help information available by typing "help" in the console.