Andrew Haley wrote:
Andrew John Hughes wrote:
Daniel's copyright assignment is finally through, so
I'm committing this patch which optimises the use of
ThreadLocals by replacing the use of the generic java.util.WeakHashMap
with a ThreadLocal-specific implementation.
It's slightly weird to be doing this in pure Java: all POSIX-
compatible systems have thread-local variables, and the glibc
implementation is very fast. Still, I'm sure this patch is an
improvement.
Andrew.
Hi Andrew,
I agree with what you say for static compilation. I think there's room
for improvement in the pthread interfaces for getting thread locals
especially if you want to have JIT compiled code that accesses them. For
example, I use the below to compute a static thread local's offset and
it is x86 specific:
#include <stdio.h>
static __thread char *hello;
int main(int argc, char **argv) {
int offset;
asm ("mov [EMAIL PROTECTED], %0" : "=r"(offset));
hello = "hello";
printf("%p %s %d",&hello, hello, offset);
}
As the patch comes from Jikes RVM it should be no surprise we addressed
solving the performance problem in a metacircular manner. I imagine
DaCapo jython is a lot faster on Classpath runtimes now.
Regards,
Ian
