JVM Stack Expansion and OutOfMemoryError

JVM Tutorials - Herong's Tutorial Examples - Version 4.23, by Dr. Herong Yang

JVM Tutorials - Herong's Tutorial Examples

∟JVM Stack Expansion and OutOfMemoryError

This section provides a tutorial example on how to test JVM footprint increases when more threads are running requiring more stacks. OutOfMemoryError occurs when Windows 32-bit system stops providing more than 1.6 GB memory.

Now let's continue our test on MultiStackThread.java with 4 threads and see the impact on the JVM footprint:

(-Xss1m)   1 Thread    4 Threads
Frames    Mem Usage    Mem Usage
     0     14,020 K     14,220 K
    10     14,128 K     14,084 K
   100     14,056 K     14,192 K
  1000     14,100 K     14,412 K
  5000     14,288 K     15,292 K
 10000     14,528 K     16,532 K
 15000     14,784 K     17,668 K
 16000     15,008 K     18,248 K (Stack overflow)
 17000     15,068 K 
 18000     15,028 K 
 18429     15,032 K (Stack overflow)

The result tells us that:

When all 4 stacks from 4 threads are full, the JVM footprint increased by 4,028 K from 14,220 K to 18,248 K. This is expected.
But when 4 threads are running, stack overflow happens earlier with the same stack size. I don't know why.

Here is the result with 16 threads. The memory usage increases as expected:

(-Xss1m)   1 Thread    4 Threads   16 Threads
Frames    Mem Usage    Mem Usage    Mem Usage
     0     14,020 K     14,220 K     14,700 K
    10     14,128 K     14,084 K     14,888 K
   100     14,056 K     14,192 K     14,804 K
  1000     14,100 K     14,412 K     16,000 K
  5000     14,288 K     15,292 K     19,732 K
 10000     14,528 K     16,532 K     24,768 K
 15000     14,784 K     17,668 K     29,640 K
 16000     15,008 K     18,248 K     33,352 K (Stack overflow)
 17000     15,068 K
 18000     15,028 K
 19000     15,032 K (Stack overflow)

If we keep increase the number of threads, the JVM should run out of memory on the Windows system. Right? Let's try it:

Threads    Mem Usage  (-Xss1m, 16000 frames)
      1     15,008 K  No error
      4     18,248 K  StackOverflow
     16     33,352 K  StackOverflow
     32     51,336 K  StackOverflow
     64     84,380 K  StackOverflow
    128    150,264 K  StackOverflow
   1024  1,072,008 K  StackOverflow
   2048               OutOfMemoryError

When I ran 2048 threads with 16000 frames, many threads reached the StackOverflow exception point and the JVM memory usage reached 1,347,520 K. Then the JVM hang after generating the following exception:

Exception in thread "main" java.lang.OutOfMemoryError: 
   unable to create new native thread
      at java.lang.Thread.start0(Native Method)
      at java.lang.Thread.start(Thread.java:713)
      at MultiStackThread.main(MultiStackThread.java:16)

The exception happened at MultiStackThread.java:16, which the "t.start();" statement. So the program failed to launch all 2048 threads.

When I tried to break the execution with <Ctrl-C>, I got the following error:

Java HotSpot(TM) Client VM warning: Exception 
java.lang.OutOfMemoryError occurred dispatching signal UNKNOWN to 
handler- the VM may need to be forcibly terminated

I had to use Task Manager to kill the JVM.

The OutOfMemoryError exception is caused by the Windows 32-bit system refusing to provide more than 1.6GB of memory to any running processes.

Last update: 2014.

Table of Contents

About This Book

Downloading and Installing JDK 1.8.0 on Windows

Downloading and Installing JDK 1.7.0 on Windows

java.lang.Runtime Class - The JVM Instance

java.lang.System Class - The Operating System

ClassLoader Class - Class Loaders

Class Class - Class Reflections

Sun's JVM - Java HotSpot VM