To: "Craig A. James" <cjames@modgraph-usa.com>
cc: Chris <dmagick@gmail.com>, pgsql-performance@postgresql.org
Subject: Re: Postgres gets stuck 
In-reply-to: <4463EE89.8010103@modgraph-usa.com> 
References: <446135F9.1060608@modgraph-usa.com> <4461391D.2000800@gmail.com>
	<44635DFE.1060509@modgraph-usa.com>
	<18707.1147392206@sss.pgh.pa.us>
	<4463EE89.8010103@modgraph-usa.com>
Comments: In-reply-to "Craig A. James" <cjames@modgraph-usa.com>
	message dated "Thu, 11 May 2006 19:10:17 -0700"
Date: Thu, 11 May 2006 22:51:12 -0400
Message-ID: <19950.1147402272@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

"Craig A. James" <cjames@modgraph-usa.com> writes:
> I guess I misinterpreted the Postgress manual, which says (in 31.9, "C Language Functions"),

>     "When allocating memory, use the PostgreSQL functions palloc and pfree
>     instead of the corresponding C library functions malloc and free."

> I imagined that perhaps palloc/pfree used mutexes for something.  But if I understand you, palloc() and pfree() are just wrappers around malloc() and free(), and don't (for example) make their own separate calls to brk(2), sbrk(2), or their kin.

Correct.  palloc/pfree are all about managing the lifetime of memory
allocations, so that (for example) a function can return a palloc'd data
structure without worrying about whether that creates a long-term memory
leak.  But ultimately they just use malloc/free, and there's certainly
not any threading or mutex considerations in there.

> No threading anywhere.  None of the libraries use threads or mutexes.  It's just plain old vanilla C/C++ scientific algorithms.

Darn, my best theory down the drain.

>> Or it could be a garden variety glibc bug.  How up-to-date is your
>> platform?

> I guess this is the next place to look.

Let us know how it goes...

			regards, tom lane