Java memory model question

[Brian Goetz]

No, but  this is a common myth.  Method boundaries are not part of the JMM, and the JIT regularly makes optimizations that have the effect of reordering operations across method boundaries.  

Sent from my iPad

> On Mar 6, 2020, at 1:04 AM, Luke Hutchison <luke.hutch at gmail.com> wrote:
> 
> Under the Java memory model, is it fair to assume that memory reads and
> writes can only be reorderered within a method, but not across method
> boundaries? (Define "method" here as what's left after any inlining has
> taken place.)
> 
> Specifically I'm wondering: if a thread X launches a parallel stream that
> writes at most once to each independent element of an array, can it be
> assumed that when the stream processing ends, X will always read the value
> of all written array elements? In other words, can the termination of the
> stream be seen as a memory ordering barrier (in a weak sense)?
> 
> I'm not asking whether the following code is advisable, only whether
> there's any chance of the main thread reading an old value from the array.
> 
>    int N = 50;
>    String[] strValues = new String[N];
>    IntStream.range(0, N)
>            .parallel()
>            .forEach(i -> strValues[i] = Integer.toString(i));
>    // (*) Are the new strValues[i] all guaranteed to be visible here?
>    for (String strValue : strValues) {
>        System.out.println(strValue);
>    }