CODEWITHSUNDEEP
javacpuperformance
user998899
user998899

Reputation: 21

How can I get the cpu usage a jvm process consumes for each cpu core using java?

Actually I'm using java to monitor the cpu usage for a certain java process.Here are my questions: First,is there a limit that a single process can only consume cpu processing time on 1 or limited cpu cores?Or it can use cpu time on each of the cpu core? Second,if I want to monitor the cpu usage of a certain java process for each cpu core,how can I do that? And I prefer to handle it using pure java,not native method.

Upvotes: 1

Views: 2063

Answers (1)

Neil Coffey
Neil Coffey

Reputation: 21815

To the operating system, a single thread (which I assume is what you mean by "Java process") essentially cannot use CPU on more than one "processor" (which may or may not mean a physical core-- see below) simultaneously.

Generally, whenever a given thread gets a "turn at running", Windows (and I assume other operating systems) will attempt to schedule a given thread on to the same "processor" that it last ran on.

However, the situation is complicated by hyperthreading CPUs which actually present to the operating system several "processors" for what is actually a single core physical core. In this case, it is actually the CPU itself that switches between what instruction of what thread is running on which component of the given core at any one time. (Because, e.g. the core's arithmetic unit could be performing an arithmetic instruction for Thread 1 while the load/store unit is fetching data from memory for an instruction for Thread 2, etc.)

So given the complexity of this situation, even if you can get per-core measurements, I'm not entirely sure quite what useful meaning you would attach to them

P.S. If you'll permit the plug, I don't know if this Java-focussed article on thread scheduling that I wrote a couple of years ago might be useful. I should say I wrote it before either Windows 7 or the latest Intel Core CPUs were released, and there may be one or two updates to the information that would be pertinent (in particular, I don't address the issue of variable core speeds and how that could affect scheduling).

Upvotes: 1

Related Questions