Message113400
| Author |
kristjan.jonsson |
| Recipients |
brian.curtin, jyasskin, kristjan.jonsson, pitrou, terry.reedy, tim.golden |
| Date |
2010年08月09日.08:40:16 |
| SpamBayes Score |
2.7729498e-05 |
| Marked as misclassified |
No |
| Message-id |
<1281343219.44.0.606270483907.issue8411@psf.upfronthosting.co.za> |
| In-reply-to |
| Content |
You wan't to have the Semaphore with a max count of infinite because
a) of the "race condition" mentioned (actually, possible discrepancy between n_waiting and actual semaphore value), which can cause the semaphore count to temporarily go positive, and
b) If you implement _cond_broadcast(), which would have code like:
int waiting = cond->n_waiting;
if (waiting > 0) {
cond->n_waiting = 0
ReleaseSemaphore(cond->sem, waiting, 0);
}
The semaphore value going above 0 is not a "bug" but an implementation detail stemming from the fact that n_waiting cannot reliably reflect the semaphore state at each particular time. Due to locking, it may lag behind the state a little bit. |
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