On Tue, Jul 25, 2017 at 5:47 AM, Petr Jelinek
<petr.jelinek@2ndquadrant.com> wrote:
> As a side note, the ConditionVariablePrepareToSleep()'s comment could be
> improved because currently it says the only advantage is that we skip
> double-test in the beginning of ConditionVariableSleep(). But that's not
> true, it's essential for preventing race conditions like the one above
> because it puts the current process into waiting list so we can be sure
> it will be signaled on broadcast once ConditionVariablePrepareToSleep()
> has been called.
But if you don't call ConditionVariablePrepareToSleep() before calling
ConditionVariableSleep(), then the first call to the latter will call
the former and return without doing anything else. So I don't see how
this can ever go wrong if you're using these primitives as documented.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
