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Re: An example of bugs for Hot Standby

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: pgsql-hackers@postgresql.org
Cc: Simon Riggs <simon@2ndquadrant.com>, Tom Lane <tgl@sss.pgh.pa.us>, Hiroyuki Yamada <yamada@kokolink.net>
Date: 2010-01-20T10:04:35Z
Lists: pgsql-hackers 
On Wednesday 20 January 2010 10:52:24 Simon Riggs wrote:
> On Wed, 2010-01-20 at 10:45 +0100, Andres Freund wrote:
> > LWLockAcquire
> 
> I'm using spinlocks, not lwlocks.
CancelDBBackends which is used in SendRecoveryConflictWithBufferPin which in 
turn used by CheckStandbyTimeout triggered by SIGALRM acquires the lwlock.

Now that case is a bit less dangerous because you would have to interrupt 
yourself to trigger a deadlock there because the code sleeps soon after 
setting up the handler.
If ever two SIGALRM occur consecutive there is a problem. 

Andres