Re: Condition variable live lock

Thomas Munro <thomas.munro@enterprisedb.com> writes:
> On Mon, Jan 8, 2018 at 12:38 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Concretely, as per attached.

> +1 for the idea.  Haven't looked at the code yet but I'll review this
> and the proclist patch shortly.

Thanks.  BTW, I realized that there is a second (and perhaps more
important) reason why we can only prepare one CV sleep at a time:
we only have one cvWaitLink in our PGPROC.  So I'm now inclined
to word the revised comment in ConditionVariablePrepareToSleep as

    /*
     * If some other sleep is already prepared, cancel it; this is necessary
     * because we have just one static variable tracking the prepared sleep,
     * and also only one cvWaitLink in our PGPROC.  It's okay to do this
     * because whenever control does return to the other test-and-sleep loop,
     * its ConditionVariableSleep call will just re-establish that sleep as
     * the prepared one.
     */

            regards, tom lane