| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | Greg Stark <gsstark(at)mit(dot)edu>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Re: pgsql: In HS, Startup process sets SIGALRM when waiting for buffer pin. |
| Date: | 2010-01-25 08:56:33 |
| Message-ID: | 4B5D5CC1.6070005@enterprisedb.com |
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| Lists: | pgsql-committers pgsql-hackers |
Simon Riggs wrote:
> On Mon, 2010-01-25 at 09:52 +0200, Heikki Linnakangas wrote:
>> Would this simple scheme work:
>>
>> When the startup process has waited for a short while (ie
>> deadlock_timeout), it sends the signal "please check if you're holding a
>> pin on buffer X" to all backends. When a backend receives that signal,
>> it checks if it is holding a pin on the given buffer *and* waiting on a
>> lock. If it is, abort the transaction. Assuming that a backend can only
>> block waiting on a lock held by the startup process, deadlock detection
>> is as simple as that.
>
> No, it won't work. A deadlock could occur after the startup process has
> already been waiting for longer than the deadlock timeout.
Retry every deadlock_timeout seconds?
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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