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What's the difference between StackOverflowError and OutOfMemoryError and how to avoid them in application?

BenMorel
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Ifozest
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7 Answers7

87

Short answer:

  • OutOfMemoryError is related to Heap.
  • StackOverflowError is related to stack

Long answer:

When you start JVM you define how much RAM it can use for processing. JVM divides this into certain memory locations for its processing purpose, two of those are Stack & Heap

If you have large objects (or) referenced objects in memory, then you will see OutofMemoryError. If you have strong references to objects, then GC can't clean the memory space allocated for that object. When JVM tries to allocate memory for new object and not enough space available it throws OutofMemoryError because it can't allocate the required amount of memory.

How to avoid: Make sure un-necessary objects are available for GC

All your local variables and methods calls related data will be on the stack. For every method call, one stack frame will be created and local as well as method call related data will be placed inside the stack frame. Once method execution is completed, the stack frame will be removed. ONE WAY to reproduce this is, have an infinite loop for method call, you will see stackoverflow error, because stack frame will be populated with method data for every call but it won't be freed (removed).

How to avoid: Make sure method calls are ending (not in an infinite loop)

USM
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kosa
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  • +1 but stackoverflow can easily be raised even when there is an ending in recursion, because stack size in Java is very small and deep recursion will hit it before end of recursion is reached. So you should favor imperative style over recursion style in java to avoid stackoverflows. – Fabian Barney Jul 11 '12 at 15:24
  • Java allocates some amount of stack space (I don't know much offhand, but i assume you might be able to configure it). If you recurse deep enough to consume all that space, you will get a StackOverflowError when java tries to allocate a new stack frame that it doesn't have room for. – Matt Jul 11 '12 at 15:32
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    @Matt: I agree and that is what I meant. I explained one of the ways and there could be more ways as Fabian commented. – kosa Jul 11 '12 at 15:34
10

StackOverflowError happens when you execute too many methods one inside another (for example with an infinite recursion), which is limited by the size of the stack.

OutOfMemoryError happens when the JVM runs out of space to allocate new objects, which are allocated on the heap.

vainolo
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8

Imagine you have a function like the following

public void f(int x) {
    return f(x + 1);
}

When you'll call it the call will call f again and again and again. At each call a bit of information is stored on the stack. Since the stack is limited in size you will get a StackOverflowError.

Now imagine the following code:

for (int i = 1; i > 0; i++)
    vector.add(new BigObject());

where BigObject is a normal Java object. As you see, the loop never terminates. Each allocation is done on the heap thus it will be filled with BigObjects and you will get an OutOfMemoryError.

To recap:

  • OutOfMemoryError is thrown when you are creating objects
  • StackOverflowError is thrown when you are calling functions
Mihai Maruseac
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3

In Java Virtual Machine there are several memory area defined :

  1. Java Virtual Machine stacks
  2. Heap area
  3. Method area
  4. Run time constant pool
  5. Native method stacks

In all above, you can choose your precision that memory allocated to those memory area will be fixed or will be changed dynamically at runtime.

Now about the question, OutOfMemoryError is applicable for all of the above listed. OutOfMemoryError will be thrown if memory expansion of any of the memory area will be attempted but enough memory is not available to allocate.

and StackOverFlowError is applicable for Native Method Stack and Java Virtual Machine Stack. StackOverFlowError will be thrown If the computation in a thread requires a larger stack than is permitted.

For Detailed reference you can read THE STRUCTURE OF THE JAVA VIRTUAL MACHINE

Not a bug
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1

The following exceptional conditions are associated with Java Virtual Machine stacks:

If the computation in a thread requires a larger Java Virtual Machine stack than is permitted, the Java Virtual Machine throws a StackOverflowError.

If Java Virtual Machine stacks can be dynamically expanded, and expansion is attempted but insufficient memory can be made available to effect the expansion, or if insufficient memory can be made available to create the initial Java Virtual Machine stack for a new thread, the Java Virtual Machine throws an OutOfMemoryError.

The following exceptional condition is associated with the heap:

If a computation requires more heap than can be made available by the automatic storage management system, the Java Virtual Machine throws an OutOfMemoryError.

The following exceptional condition is associated with the method area:

If memory in the method area cannot be made available to satisfy an allocation request, the Java Virtual Machine throws an OutOfMemoryError.

The following exceptional condition is associated with the construction of the run-time constant pool for a class or interface:

When creating a class or interface, if the construction of the run-time constant pool requires more memory than can be made available in the method area of the Java Virtual Machine, the Java Virtual Machine throws an OutOfMemoryError.

The following exceptional conditions are associated with native method stacks:

If the computation in a thread requires a larger native method stack than is permitted, the Java Virtual Machine throws a StackOverflowError.

If native method stacks can be dynamically expanded and native method stack expansion is attempted but insufficient memory can be made available, or if insufficient memory can be made available to create the initial native method stack for a new thread, the Java Virtual Machine throws an OutOfMemoryError.

https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-2.html

2.5.2. Java Virtual Machine Stacks

2.5.3. Heap

2.5.4. Method Area

2.5.5. Run-Time Constant Pool

2.5.6. Native Method Stacks

2.6. Frames

Arshak Manukyan
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0

From Javadocs: Exceptional conditions associated with JVM Stacks:

1) if insufficient memory can be made available to create the initial JVM stack for a new thread, the JVM throws an OutOfMemoryError.

2) If the computation in a thread requires a larger JVM stack than is permitted, the JVM throws a StackOverflowError.

3) If JVM stack can be dynamically expanded, and expansion is attempted but insufficient memory can be made available to effect the expansion, the JVM throws an OutOfMemoryError.

Exceptional conditions associated with Heap:

1) If a computation requires more heap than can be made available by the automatic storage management system, the JVM throws an OutOfMemoryError.

Raúl
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Through the JVM specification, there are 5 data areas.

For JVM Stacks data areas, the spec said the memory size of JVM Stacks can be fixed or dynamically adjustable like the heap area.

When runs out of JVM Stacks memory, there are two cases:
1. If JVM Stacks is implemented as a fixed size, JVM will throw a StackOverflowError.
2. Otherwise, just like the heap area, JVM will throw OutOfMemoryError when failed to allocate more memory.

Any not only for the JVM Stacks area, memory allocations for other data areas will also case OutOfMemoryError due to insufficient memory resources.

For more information, see the JVM specification - Run-Time Data Areas

EI CHO
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