How much memory is my Java process using?

Many commands can check the memory utilization of JAVA processes, for example, pmap, ps, jmap, jstat….

1. ps and pmap can show total reserved memory from OS.
2. jmap and jstat can show used space of heap&stack.
3. jmap -histo can show top heap memory objects.

How can we find the memory usage of JVM from Java code?

To get the JVM memory information with Runtime class you should:

1. Use getRuntime() API method of Runtime. This method returns the runtime object associated with the current Java application.
2. Use freeMemory() API method of Runtime.
3. Call maxMemory() API method of Runtime.
4. Call totalMemory() API method of Runtime.

How do I make Java use less memory?

Preferably the heap should be at least twice the size of the total amount of live objects, or large enough so that the JVM spends less time garbage collecting the heap than running Java code. To allow the heap to grow and shrink depending on the amount of free memory in your system, set -Xms lower than -Xmx .

Why does Java use so much RAM?

Java is also a very high-level Object-Oriented programming language (OOP) which means that while the application code itself is much easier to maintain, the objects that are instantiated will use that much more memory.

Does Java use a lot of RAM?

How to check the memory utilization in Java?

Many commands can check the memory utilization of JAVA processes, for example, pmap, ps, jmap, jstat. What are the differences? Before we move forward, we need to know heap and stack. Simply saying, heap space contains 1 Eden space , 2 young generations and 1 old generation; stack space is the permanent generation.

Why does my Java program always return the same memory usage?

But the reason your program always returns the same memory usage is because you are not creating enough objects to overcome the precision limitations of the freeMemory method. Although it has byte resolution, there is no guarantee for how precise freeMemory needs to be. The javadoc says as much:

How much memory does freememory use in Java?

The numbers suggest freeMemory for the JVM I’m using (Java7 Win 64-bit) has a precision of just over 2.5MB (although if you run the experiment, you’ll see this number varies). This code is the same as above, but prints more details about memory usage.

How to control heap size ( memory allocation ) in Java?

The short answer The short answer is that you use these Java command-line parameters to help control the RAM use of application: Use -Xmx to specify the maximum heap size Use -Xms to specify the initial Java heap size