Red Hat
Mar 8, 2010
by Kabir Khan
For those of you familiar with the Twiddle application, which allows you to inspect the JMX MBeans in JBoss Application Server, I have created a similar tool for use with the JBoss Microcontainer. This means that you can now manage and inspect ALL the beans in the JBoss Application Server (or in a standalone Microcontainer application). I'll briefly outline the existing functionality below and how to use it. The functionality supported so far is quite basic, but hopefully it will be useful to somebody. I'll be adding more commands to it when I have the time.

Implementing commands to extend the feature set is very easy. If you would like to be a Microcontainer committer, this is a great opportunity to get involved by implementing something simple while you get to know the code and the team. If you are interested please contact me privately or via our forums.

Installation
If you want to run this in a standalone environment you simply create an instance of org.jboss.microcontainer.mcinspector.bean.McInspector and pass it your bootstrapped kernel as shown in the test cases. To install it into a JBoss Application Server installed to ~/jbossas/:



That's all, now start up JBoss as normal, and in another terminal: cd ~/jbossas/bin. This last terminal is the one we will be using to try out the commands in the rest of this demo.

Help
To get help you enter: ./mcinspector.sh help, which gives you an overview of the commands available. The command and its output are shown below:
$./mcinspector.sh help
Available commands:
  help   Prints the list of available commands.
  list   Lists all the available contexts.
  change Changes the state of the context.
  bean   Inspect a particular bean.
For more information about a particular command, enter 'help '.
Handled in 1026ms

You can also get more information about a particular command, e.g.:
$./mcinspector.sh help list
Lists all the contexts in the controller.
Usage: list [-o | -v] [ []*]
If no state arguments are passed in all states will be checked for contexts. Otherwise
only the passed in states will be checked
Options:
-o Overview. Show all the states in the controller with the number of contexts in each
   Normally only states with contexts will be shown
-e Error. Show only the contexts which are in the error state. Can not be used in combination  
   with state arguments.
-v Verbose. Show extra information for each context. Contexts with unresolved dependencies
   will have a '*' after their name. Additional information is in the format 
   (ControllerMode, Current state)
Handled in 523ms

List
Let's try out the list command. As promised in the help section, it lists all the states, in ascending order, in the Application Server's main controller and displays the number of beans found in each state:

$./mcinspector.sh list -o
NOT INSTALLED: 0 contexts
PREPARSE: 0 contexts
PARSE: 0 contexts
POSTPARSE: 0 contexts
PREDESCRIBE: 0 contexts
DESCRIBE: 0 contexts
CLASSLOADER: 0 contexts
POSTCLASSLOADER: 0 contexts
PREREAL: 0 contexts
REAL: 0 contexts
PREINSTALL: 0 contexts
DESCRIBED: 33 contexts
INSTANTIATED: 0 contexts
CONFIGURED: 0 contexts
CREATE: 0 contexts
START: 0 contexts
INSTALLED: 997 contexts
Handled in 509ms

To view which beans are in the different states we execute ./mcinspector.sh list. Since there are lot of beans in the Application Server I have deleted most of the output below:

DESCRIBED:
JBossLogManagerContextSelectorService
org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory
org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory
org.jboss.netty.channel.socket.nio.NioDatagramChannelFactory
org.jboss.netty.channel.socket.oio.OioClientSocketChannelFactory
org.jboss.netty.channel.socket.oio.OioServerSocketChannelFactory
org.jboss.netty.channel.socket.oio.OioDatagramChannelFactory
org.jboss.netty.channel.local.DefaultLocalClientChannelFactory
org.jboss.netty.channel.local.DefaultLocalServerChannelFactory
ModClusterListener
ModClusterService
...
INSTALLED:
JBossServer
ClassLoaderSystem
ClassLoaderDomain
ClassLoading
bootstrap-classloader:0.0.0$MODULE
bootstrap-classloader:0.0.0
stdio-classloader:0.0.0$MODULE
stdio-classloader:0.0.0
JBossStdioSystemOutStream
JBossStdioSystemErrStream

McInspectorCommands
McInspector
org.jboss.kernel:service=McInspector
McInspectorHelpCommand
McInspectorListCommand
McInspectorChangeCommand
McInspectorBeanCommand
file:///Users/kabir/sourcecontrol/jbossas/trunk/subversion/build/target/jboss-6.0.0-SNAPSHOT/server/default/deploy/mcinspector.jar
Handled in 596ms

To get more information about the contexts for a given state, you can do ./mcinspector.sh list -v DESCRIBED. The verbose output currently shows the controller mode of the beans' contexts, along with the current state of the bean. The * means that the context has unresolved dependencies.

$./mcinspector.sh list -v DESCRIBED
DESCRIBED:
JBossLogManagerContextSelectorService* (ON_DEMAND, DESCRIBED)
org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory* (ON_DEMAND, DESCRIBED)
org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory* (ON_DEMAND, DESCRIBED)
org.jboss.netty.channel.socket.nio.NioDatagramChannelFactory* (ON_DEMAND, DESCRIBED)
org.jboss.netty.channel.socket.oio.OioClientSocketChannelFactory* (ON_DEMAND, DESCRIBED)
org.jboss.netty.channel.socket.oio.OioServerSocketChannelFactory* (ON_DEMAND, DESCRIBED)
org.jboss.netty.channel.socket.oio.OioDatagramChannelFactory* (ON_DEMAND, DESCRIBED)
org.jboss.netty.channel.local.DefaultLocalClientChannelFactory (ON_DEMAND, DESCRIBED)
org.jboss.netty.channel.local.DefaultLocalServerChannelFactory (ON_DEMAND, DESCRIBED)
ModClusterListener* (ON_DEMAND, DESCRIBED)
ModClusterService* (ON_DEMAND, DESCRIBED)
HAModClusterService* (ON_DEMAND, DESCRIBED)
ModClusterConfig* (ON_DEMAND, DESCRIBED)
DynamicLoadBalanceFactorProvider* (ON_DEMAND, DESCRIBED)
AverageSystemLoadMetric* (ON_DEMAND, DESCRIBED)
OperatingSystemLoadMetricSource (ON_DEMAND, DESCRIBED)
BusyConnectorsLoadMetric* (ON_DEMAND, DESCRIBED)
ThreadPoolLoadMetricSource* (ON_DEMAND, DESCRIBED)
SimpleLoadBalanceFactorProvider* (ON_DEMAND, DESCRIBED)
SystemMemoryUsageLoadMetric* (ON_DEMAND, DESCRIBED)
HeapMemoryUsageLoadMetric* (ON_DEMAND, DESCRIBED)
RequestCountLoadMetric* (ON_DEMAND, DESCRIBED)
ReceiveTrafficLoadMetric* (ON_DEMAND, DESCRIBED)
SendTrafficLoadMetric* (ON_DEMAND, DESCRIBED)
RequestProcessorLoadMetricSource* (ON_DEMAND, DESCRIBED)
ActiveSessionsLoadMetric* (ON_DEMAND, DESCRIBED)
SessionLoadMetricSource* (ON_DEMAND, DESCRIBED)
ConnectionPoolUsageMetric* (ON_DEMAND, DESCRIBED)
ConnectionPoolLoadMetricSource* (ON_DEMAND, DESCRIBED)
MBeanAttributeLoadMetric* (ON_DEMAND, DESCRIBED)
MBeanAttributeRatioLoadMetric* (ON_DEMAND, DESCRIBED)
MBeanQueryLoadMetricSource* (ON_DEMAND, DESCRIBED)
XnioProvider* (ON_DEMAND, DESCRIBED)
Handled in 479ms

Bean
To get more information about one or more beans in particular, you can run the bean command. e.g.:
$./mcinspector.sh bean ModClusterListener ModClusterService
Name='ModClusterListener'
  bean type=org.jboss.modcluster.catalina.CatalinaEventHandlerAdapter
  mode=ON_DEMAND
  state=DESCRIBED
  required state=DESCRIBED
  context type=org.jboss.kernel.plugins.dependency.AbstractKernelControllerContext
  unresolved dependencies=1
Name='ModClusterService'
  bean type=org.jboss.modcluster.ModClusterService
  mode=ON_DEMAND
  state=DESCRIBED
  required state=DESCRIBED
  context type=org.jboss.kernel.plugins.dependency.AbstractKernelControllerContext
  unresolved dependencies=5
Handled in 485ms

To get some more information about the dependencies, you can pass in the -d flag
$./mcinspector.sh bean -d ModClusterListener
Name='ModClusterListener'
  bean type=org.jboss.modcluster.catalina.CatalinaEventHandlerAdapter
  mode=ON_DEMAND
  state=DESCRIBED
  required state=DESCRIBED
  context type=org.jboss.kernel.plugins.dependency.AbstractKernelControllerContext
  unresolved dependencies=1
  Resolved dependencies:
  Unresolved dependencies:
    iDependOn=ModClusterService; whenRequired=INSTANTIATED; dependentState=INSTALLED

The -u flag is the same as -d apart from it does not look for resolved dependencies:

$./mcinspector.sh bean -d ModClusterListener
Name='ModClusterListener'
  bean type=org.jboss.modcluster.catalina.CatalinaEventHandlerAdapter
  mode=ON_DEMAND
  state=DESCRIBED
  required state=DESCRIBED
  context type=org.jboss.kernel.plugins.dependency.AbstractKernelControllerContext
  unresolved dependencies=1
  Unresolved dependencies:
    iDependOn=ModClusterService; whenRequired=INSTANTIATED; dependentState=INSTALLED
Handled in 492ms


Change
Finally there is the change command which attempts to change the state of a bean, so it can for example be used to temporarily disable a bean. Only do this if you know what you are doing! For example, let us try to stop the bean that implements the MC Inspector's bean command:

$./mcinspector.sh change INSTANTIATED McInspectorBeanCommand
Changed 'McInspectorBeanCommand' to INSTANTIATED
Handled in 473ms

This has stopped the bean implementing the bean command, so bean no longer appears in the list of available commands:
$./mcinspector.sh help
Available commands:
  help Prints the list of available commands.
  list Lists all the available contexts.
  change Changes the state of the context.
  For more information about a particular command, enter 'help '.
Handled in 497ms

And it appears in the INSTANTIATED state:
$./mcinspector.sh list INSTANTIATED -v
INSTANTIATED:
McInspectorBeanCommand (AUTOMATIC, INSTANTIATED)
Handled in 488ms


Let us make it installed again:
$./mcinspector.sh change INSTALLED McInspectorBeanCommand
Changed 'McInspectorBeanCommand' to INSTALLED
Handled in 474ms

Now bean appears in the list of available commands again:
$./mcinspector.sh help
Available commands:
  help Prints the list of available commands.
  list Lists all the available contexts.
  change Changes the state of the context.
  bean Inspect a particular bean.
For more information about a particular command, enter 'help
'.
Handled in 480ms