How to get cpu load (%), overall and per core, in Java?

Question

I need to run a cpu load monitor on a server. I'd like to create a separate process for that purpose, instead of instrumenting a messy blob of server application code. The question is simple though:

How can I get the system cpu usage (overall and per core, in percentage) using Java?

I've checked OperatingSystemMXBean.getSystemLoadAverage(), but it gives me the average system cpu load of the last minute, which is too long for me. I need to monitor the load every second (or less). Besides this one give the overall system cpu load.

Finally, is it possible to get the cpu usage of threads that belong to another Java process?

Peter Lawrey · Accepted Answer · 2013-09-08 20:06:11Z

1

You need to run mpstat on Linux in Runtime.exec() and parse the output. I don't know if there is anything similar on Windows.

$ mpstat -A 10
Linux 3.8.0-27-generic (peter-hex)  08/09/13    _x86_64_    (12 CPU)

21:04:39     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
21:04:49     all    0.27    0.00    0.18    0.00    0.00    0.00    0.00    0.00   99.55
21:04:49       0    0.40    0.00    0.20    0.00    0.00    0.00    0.00    0.00   99.40
21:04:49       1    0.80    0.00    0.50    0.00    0.00    0.00    0.00    0.00   98.70
21:04:49       2    0.50    0.00    0.40    0.00    0.00    0.00    0.00    0.00   99.10
21:04:49       3    0.80    0.00    0.50    0.00    0.00    0.00    0.00    0.00   98.70
21:04:49       4    0.10    0.00    0.20    0.00    0.00    0.00    0.00    0.00   99.70
21:04:49       5    0.70    0.00    0.40    0.00    0.00    0.00    0.00    0.00   98.90
21:04:49       6    0.10    0.00    0.00    0.00    0.00    0.00    0.00    0.00   99.90
21:04:49       7    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
21:04:49       8    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
21:04:49       9    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
21:04:49      10    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
21:04:49      11    0.00    0.00    0.10    0.00    0.00    0.00    0.00    0.00   99.90

is it possible to get the cpu usage of threads that belong to another Java process?

Yes, you can use ps -eLf and see all threads on the system. This gives you the CPU used since starting. (From which you can calculate utilisation if you want)

answered Sep 8, 2013 at 20:06

Peter Lawrey

535k83 gold badges770 silver badges1.2k bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Eduardo Bezerra Over a year ago

Right, it's not very platform independent, but works for now. How would I call mpstat with Runtime.exec and parse the output though? Could you please add code showing that?

Peter Lawrey Over a year ago

I would use a BufferedReader and split("\\s+") each lines to get the words. System monitoring is system dependent fundamentally. e.g. getSystemLoadAverage() doesn't work on Windows either.

Eduardo Bezerra Over a year ago

How do I get get the current load of the system? If I call mpstat -P ALL, I get the statistics since the start of the machine.

Collectives™ on Stack Overflow

How to get cpu load (%), overall and per core, in Java?

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related