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javamonitoringcpu
Eduardo Bezerra
Eduardo Bezerra

Reputation: 1963

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

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?

Upvotes: 0

Views: 2184

Answers (1)

Peter Lawrey
Peter Lawrey

Reputation: 533492

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)

Upvotes: 1

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