Re: ThreadPoolExecutor backport

Robert Klemme wrote:
I faintly remember articles
about the flaws of the Java memory model before Java 5 and I believe
volatile handling was one of them.  Or am I mixing up something?

What you are remembering is that 'volatile' prior to Java 5 only
guaranteed visibility of changes through the volatile variable
itself. Other changes might not have propagated.

So given

class Foo
{
volatile int flag;
int value; // not volatile
...
}

the old memory model would guarantee visbility of changes to 'flag',
but not other changes. Code like:

value += 17;
flag = 1;

in one thread guaranteed that another thread would see 'flag' as 1,
but not that it would see the change in 'value'. In the new memory
model, the change to 'value' /happens-before/ the change to 'flag', so
it is visible across threads.

--
Lew
.

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