> From: Yilong Li [mailto:yilong...@runtimeverification.com]
> Subject: Re: RV-Predict bugs
> Well, it is the problem (at least part of it) because JLS says "Informally,
> a read *r* is allowed to see the result of a write *w* if there is no
> *happens-before* ordering to prevent that read." In this case, there is no
> HB ordering preventing event 3 to read the initial null value put by JVM.
True, but as Mark previously pointed out, no one cares. All that happens in
that case is the object is redundantly created and then garbage collected
later; no damage.
> But consider the following hashcode example:
> public int hashCode() {
> if (hashCode == 0) {
> hashCode = computeHashCode(); // no object creation involved
> }
> return hashCode;
> }
> There is no object initialization/publication involved at all but the
> problem still exists: this method could return 0 even if the if-statement
> sees a non-zero value.
No, it can't (unless computeHashCode() returns a zero, which presumably it
won't). This is all action within a single thread, and as such must obey
intra-thread semantics (i.e., statements are executed in control flow order).
- Chuck
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