JavaResourceMonitor Agent

JavaResourceMonitor is a java agent that can be attached to IBM Java on startup to monitor its resource usage. Currently the agent profiles the JVM for CPU usage which is obtained using com.ibm.lang.management.JvmCpuMonitorMXBean. The CPU usage is recorded in a file named cpulogs in current directory.

Usage

Run following command in the directory javaresourcemonitor to compile the java agent and generate the jar file javaresourcemonitor.jar:

gmake

The agent accepts two optional parameters:

• frequency - frequency of profiling the JVM. It is specified in milliseconds. Default value is 1000 ms.
• duration - duration of profiling the JVM from startup. It is specified in seconds. Default value is 0 which means profile JVM for its whole duration.

You can use the agent as:

• java -javaagent:<path to javaresourcemonitor.jar> <Application>

In the above case, the agent would profile JVM for CPU usage at a frequency of 1000 ms for the duration of the application.

• java --javaagent:<path to javaresourcemonitor.jar>=frequency=10000,duration=30 <Applicatioin>

In this case, the agent would profile JVM for CPU usage at a frequency of 10000 ms for a duration of 30 secs or for the duration of the application, whichever is smaller.

In all cases, the agent records the profiling information in cpulogs file in current working directory.

Explanation of output

As stated earlier, the agent uses com.ibm.lang.management.JvmCpuMonitorMXBean to get CPU usage. The JvmCpuMonitorMXBean provides APIs to obtain JVM CPU usage information in terms of thread categories. The agent records the CPU usage of JVM in terms of following thread categories as defined by JvmCpuMonitorMXBean:

• System-JVM
• Application
• Resource-Monitor

For each of these categories, the agent reports the absolute CPU usage in microseconds in the last sample, and its percentage with respect to overall CPU usage.

System-JVM usage is further divided into GC, JIT and Others sub-categories but only their percentage with respect to System-JVM usage is recorded by the agent.

An example of the information recorded in cpulogs by the agent is:

    Timestamp(s)      R-Mon(us)   R-Mon(%)        App(us)     App(%)     System(us)  System(%) [     GC(%)     JIT(%)  Others(%)]
           0.000              0          -              0          -              0          - [         -          -          -]
           1.044           9234      0.44%        1868481     89.50%         209967     10.06% [     0.00%    100.00%      0.00%]
           2.059           7700      0.38%        1816295     89.57%         203798     10.05% [     0.00%    100.00%      0.00%]
           3.063           4075      0.20%        1800945     89.75%         201671     10.05% [     0.00%    100.00%      0.00%]
           4.068           4103      0.20%        1799432     89.73%         201880     10.07% [     0.00%    100.00%      0.00%]
           5.072           3778      0.19%        1798003     89.62%         204477     10.19% [     0.00%    100.00%      0.00%]
           6.075           3813      0.19%        1920306     95.74%          81664      4.07% [     0.00%    100.00%      0.00%]
           7.172          17819      0.82%        2131800     97.98%          26127      1.20% [     0.00%    100.00%      0.00%]
           8.176           4223      0.21%        1952540     97.66%          42521      2.13% [     0.00%    100.00%      0.00%]
           9.180           3651      0.18%        1995804     99.58%           4707      0.23% [     0.00%    100.00%      0.00%]
          10.186           3537      0.18%        1985705     98.73%          21941      1.09% [     0.00%    100.00%      0.00%]

The output consists of following columns:

• Timestamp: records the timestamp of the sample since the start of the application.
• R-Mon(us): records the CPU usage in last sample by Resource-Monitor category
• R-Mon(%): records the CPU usage in last sample by Resource-Monitor category in terms of percentage
• App(us): records the CPU usage in last sample by Application category
• App(%): records the CPU usage in last sample by Application category in terms of percentage
• System(us): records the CPU usage in last sample by System-JVM category
• System(%): records the CPU usage in last sample by System-JVM category in terms of percentage
• GC(%): records the CPU usage in last sample by GC sub-category in terms of percentage of System-JVM category
• JIT(%): records the CPU usage in last sample by JIT sub-category in terms of percentage of System-JVM category
• Others(%): records the CPU usage in last sample by Others sub-category in terms of percentage of System-JVM category