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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