JVM and Java Linux process

Question

This question may be very basic about Java JVM. If I've a Java standalone program and if, for example, 5 processes of this program are running at a particular time in the server, can we say that these 5 java processes are running in 5 JVMs?

By process, I mean the Linux process here. If I execute ps -ef |grep java, I'll see 5 java processes showing up.

code.google.com/p/jvmtop displays all jvms

MRalwasser
– MRalwasser

2013-03-14 10:43:34 +00:00
Commented Mar 14, 2013 at 10:43 — MRalwasser
– MRalwasser, Commented Mar 14, 2013 at 10:43

Matthew Flaschen · Accepted Answer · 2010-11-29 07:05:34Z

12

Yes, that's correct. There is one JVM per java process.

answered Nov 29, 2010 at 7:05

Matthew Flaschen

286k53 gold badges523 silver badges554 bronze badges

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

2 Comments

Gnanam Over a year ago

Can we say # of java processes equals # of JVMs running at all cases?

Matthew Flaschen Over a year ago

In a normal Linux setup, as described in your question. There are possible solutions for attempting more than one JVM per process. See this (old) article, for instance.

CruiZen · Accepted Answer · 2011-11-04 15:22:30Z

5

You can run the jps command (from the bin folder of JDK if it is not in your path) to find out what java processes (JVMs) are running on your machine.

edited Nov 4, 2011 at 15:22

answered Nov 1, 2011 at 14:25

CruiZen

1822 silver badges6 bronze badges

2 Comments

CruiZen Over a year ago

@Gnanam : You will find the jps command useful in another situation. It is normally used to find out the process id of your java process, which can be passed to an application like a profiler like VisualVM (invoked with jvisualvm comamnd) or the jhat utility to take heap dumps.

Gnanam Over a year ago

Thanks once again for letting me know the existence of another Heap Analysis tool jhat.

Jé Queue · Accepted Answer · 2010-11-29 07:22:16Z

0

Depends on the JVM and native libs. You may see JVM threads show up with distinct PIDs in ps. Generally speaking the child PIDs will have parent PIDs with java processes as those that are threads.

You cannot say for sure that the # of Linux java processes == # of instantiated JVMs.

answered Nov 29, 2010 at 7:22

Jé Queue

10.7k14 gold badges59 silver badges62 bronze badges

2 Comments

Matthew Flaschen Over a year ago

On Linux, the JVM uses true native threads, which are similar to processes. However, they are not the same thing, as only a process has its own address space.

Matthew Flaschen Over a year ago

I'm addressing your last paragraph. I think you can say that (process count does equal JVM count) for sure, regardless of ps output.

Collectives™ on Stack Overflow

JVM and Java Linux process

3 Answers 3

2 Comments

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related