Re: stack size to small?

The alt stack is allocated during thread creation. OutOfMemoryError
might be a better choice than outright fatal. But keep in mind
OutOfMemoryError is already very generic, it's not so easy to
figure out what actually caused the OOM. Like I said, a better fix
is to not use alt stack at all. It is implemented in 1.5.

thanks,
-hui

Joseph Shraibman wrote:
> This alt stack is allocated when?  I'm confused.  If at thread creation, 
> then the thread.start() should fail with an OutOfMemError.  If it is 
> allocated when a stack overflow occurs, well of course there won't be 
> space to allocate the alt stack because we just had a stack overflow
> 
> Hui Huang wrote:
> 
>> JVM fataled because it's an irrecoverable error (i.e. not as
>> simple as StackOverflowError).
>>
>> Prior to 1.5, Sun's JDK needs to allocate alternate signal stack
>> to handle stack overflows. For compatibility reasons, the alt
>> stack is actually allocated within the normal thread stack. If a
>> thread (either a pure Java thread or a native thread attached to
>> VM) does not have enough stack space for the alt stack, JVM will
>> have to abort (JVM can't continue because signal handlers have
>> already been set up to use alternate signal stack; each thread
>> must have its own alt stack, if any thread is missing alt stack,
>> you'll end up having two threads sharing the stack space, which
>> will lead to crashes that are much harder to diagnose).
>>
>> Alt signal stacks have been removed in 1.5. I'd recommend you to
>> try JDK 1.5-beta, which is available at java.sun.com. You might
>> also want to check your code (both Java and native) to see if
>> you are creating threads with small stack. Before 1.5, the minimum
>> stack size allowed is 96k.
>>
>> regards,
>> -hui
>>
>> Joseph Shraibman wrote:
>>
>>> That's what StackOverflowError is for.  It shouldn't crash the jvm
>>>
>>> Dan Kegel wrote:
>>>
>>>> Joseph Shraibman wrote:
>>>>
>>>>> I had a jvm running for a few hours when it suddenly quit with:
>>>>>
>>>>> Fatal: Stack size too small. Use 'java -Xss' to increase default 
>>>>> stack size.
>>>>>
>>>>>
>>>>> WTF?
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Maybe you allocated something huge on the stack, or had
>>>> too many levels of nested calls...
>>>>
>>>
>>>
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> 



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