Re: Interruptible sleeps (was Re: CommitFest 2009-07: Yay, Kevin! Thanks, reviewers!)

On 27/08/10 10:39, Fujii Masao wrote:
> On Thu, Aug 26, 2010 at 7:40 PM, Heikki Linnakangas
> <heikki.linnakangas@enterprisedb.com>  wrote:
>> There's two kinds of latches, local and global. Local latches can only be
>> set from the same process - allowing you to replace pg_usleep() with
>> something that is always interruptible by signals (by setting the latch in
>> the signal handler). The global latches work the same, and indeed the
>> implementation is the same, but the latch resides in shared memory, and can
>> be set by any process attached to shared memory. On Unix, when you set a
>> latch waited for by another process, the setter sends SIGUSR1 to the waiting
>> process, and the signal handler sends the byte to the self-pipe to wake up
>> the select().
>
> According to this explanation, the latch which walsender uses seems to be
> local. If it's true, walsender should call InitSharedLatch rather than
> InitLatch?

Yes, it should.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com