We often need to find CPU and memory utilization of a particular Java
process in order to get some performance stats, capacity planning or just to
understand the current load on system. Performance monitoring and testing is
integral part of any Java application development, especially if you are
working in high frequency trading space. In order to fix a performance problem,
you have to find them first and knowledge of right tools and commands helps
there. One of the primary cause of poor application performance be it Java or
any other process is exhaustion of important resources like CPU and memory. Monitoring
CPU and memory utilization of your Java process gives you some useful insight
like what is normal memory and CPU utilization, when are you getting spikes on CPU and memory consumption. If heap memory is constantly
increasing over time than it’s an indication that your Java application may
have a memory leak. In this Java performance tutorial, we will learn about two
most common Solaris commands prstat and pmap to find
CPU and memory utilization of Java process. prstat is a
process monitoring tool easily available in any Solaris systems including SPARC
and x86 boxes, which provides useful statics of CPU and memory utilization of a
process. For other systems e.g. windows you can use windows task manager for CPU monitoring and Linux you can use top command
for same purpose. By the way, you can also check out Java performance by Charlie Hunt and BinuJohn, it is immensely helpful for Java performance monitoring and
tuning. This is the book, which gives you right kind of tools and knowledge
required to find performance stats for Java application.
Solaris command to find CPU and Memory
utilization of Java process
prstat command in UNIX, particularly in Solaris can be used to findmemory and CPU consumption of a Java application. prstat needs,
process id to show statics of particular process, which can be obtained by
using ps command in UNIX, as shown below.
1. Find the PID of Java process
ps -ef | grep "MyJavaSever"
2) Find CPU and Memory usage of Java process
prstat -p 28983 5
PID USERNAME
SIZE RSS STATE
PRI NICE TIME CPU PROCESS/NLWP
29389 appsvs
1129M 445M sleep
47 4 0:03:44 0.0%
java/49
Now most important thing is to understand output of prstat command, two
columns which are most important are RSS and and CPU. If you
look man page for Solaris prstat command, RSS denotes total amount of physical memory used by process and CPU denotes total
percentage of CPU used by that Java process. RSS stands for Resident Set
Size and shows total physical memory used by process on Kilobytes(K),
Megabytes(M) and Gigs(G). On the other hand we have another memory stats denoted
by SIZE which shows total size of virtual memory used by Java process or any
other process including mapped files and devices. SIZE denotes
size of virtual memory in Kilobytes(K), Megabytes(M) or Gigabytes(G).
TIME denotes total time duration for which that
particular Java process is running.
USERNAME shows the Solaris user account
on which process is started and running.
PRI denotes priority of your Java process. Higher
the number means Higher the priority of Java process you are monitoring.
You can see that prstat is very useful command and also
easily available on almost every Solaris machine, It answer fundamental
questions like How much CPU and memory is
currently utilized and which process are using those. It also provides
useful details related to process/threads. You can also run prstat
command with an interval as in above example CPU and memory stats will be updated
every five seconds. You can also record this data to analyze CPU and memory
utilization over a period of time to find issues and performance stats. Simply
redirect output of prstat command to a file. If you are interested in further reading than second chapter from Java performance book, is
another great read on this topic, which discusses about CPU utilization, memory
utilization, network I/O utilization and disk I/O utilization on all major
operation system including Windows, Linux, and Solaris.
Some of the useful option of PRSTAT command
in Solaris:
Following are some of the useful options of prstat utility, worth
remembering.
interval You can define interval
in seconds after which prstat will update CPU and memory utilization
-s To sort the output of
prstat, you can sort output of prstat command
in Solaris on CPU, pri, rss, size, time columns.
-c To run prstat in continuous mode,
which print new stats after specified interval in new lines instead of
overwriting existing details, this can
be used to record prstat output over period of time. by running prstat
into continuous mode we can generate useful reports which shows CPU and memory utilized by Java process by
an hour, a day or a week depending upon duration on which you run prstat in continuous mode.
Another command which can be used to find memory utilization of a
process in Sun Solaris operating system is "pmap". but there
is one limitation of pmap command, you can only run pmap command
with the user id which is used to
start the corresponding Java process, other wise you will get permission denied
error as shown below :
pmap 29389
pmap: cannot examine
29389: permission denied
pmap command in Solaris shows address information
of a Java process
That’s all on How to find CPU and Memory usage of a Java program in
Solaris. If you are working in Linux environment and don’t have access
to prstat process monitoring utility, you may want to check top and pstree, which are
Linux equivalent of Solaris prstat. On closing noted, Java performance book by Charlie hunt
and Binu John mentioned in my list of must read books for Java developer,
has several techniques and command to find memory and CPU utilization in
Windows, Solaris and Linux. If you are serious about mastering performance
tuning and benchmarking Java application, they you should spend some time with
this book. One of the best book for performance monitoring and tuning Java
application. At the very least you can
plug JConsole to your Java application and monitor memory usage, thread usage
and deadlock
Related Java and UNIX command tutorials from Javarevisited
Source:http://javarevisited.blogspot.com/2013/06/find-cpu-and-memory-used-by-java-solaris-prstat-command-example.html
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