Re: small parallel restore optimization - Mailing list pgsql-hackers

From Alvaro Herrera
Subject Re: small parallel restore optimization
Date
Msg-id 20090309012553.GO3821@alvh.no-ip.org
Whole thread Raw
In response to Re: small parallel restore optimization  (Andrew Dunstan <andrew@dunslane.net>)
Responses Re: small parallel restore optimization
List pgsql-hackers
Andrew Dunstan wrote:

> I have found the source of the problem I saw. dumputils.c:fmtId() uses a  
> static PQExpBuffer which it initialises the first time it's called. This  
> gets clobbered by simultaneous calls by Windows threads.
>
> I could just make it auto and set it up on each call, but that could  
> result in a non-trivial memory leak ... it's probably called a great  
> many times. Or I could provide a parallel version where we pass in a  
> PQExpBuffer that we create, one per thread, and is used by anything  
> called by the parallel code. That seems like a bit of a potential  
> footgun, though.

Could you use a different static PQExpBuffer on each thread?
pthread_getspecific sort of thing, only to be used on Windows.

BTW does fmtQualifiedId have the same problem?

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.


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