I ran into this tidbit today in some Sun online training material on
JDK1.2:
> The JIT compiler also achieves a minor performance gain by not pre-checking certain
>Java
> boundary conditions such as Null pointer or array out of bounds exceptions. The only
>way
> the JIT compiler knows it has a null pointer exception is by a signal raised by the
>operating
> system. Because the signal comes from the operating system and not the Java VM, your
> program takes a performance hit. To ensure the best performance when running an
> application with the JIT, make sure your code is very clean with no errors like Null
>pointer or
> array out of bounds exceptions.
I suppose this is describing the sunwjit compiler, and not a general
condition that JITs are required to handle. But it does seem a bit
dicey, relying on signals to detect conditions that might not raise a
signal, and -- relevant to the Blackdown porting challenges -- relying
on a mechanism that seems to be very troublesome in the Linux
multi-threaded environment.
Has this JIT feature been causing any problems in the Blackdown port?
Nathan Meyers
[EMAIL PROTECTED]
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