* Tom Lane:
Well, the fundamental point is that ignoring NFS is not the real
world. We can't tell people not to put data directories on NFS,
and even if we did tell them not to, they'd still do it. And NFS
locking is not trustworthy, because the remote lock daemon can crash
and restart
On Apr 13, 2011, at 9:30 PM, Robert Haas wrote:
On Wed, Apr 13, 2011 at 6:11 PM, A.M. age...@themactionfaction.com wrote:
I don't see why we need to get rid of SysV shared memory; needing less
of it seems just as good.
1. As long one keeps SysV shared memory around, the postgresql project
On Apr 14, 2011, at 8:22 AM, Florian Weimer wrote:
* Tom Lane:
Well, the fundamental point is that ignoring NFS is not the real
world. We can't tell people not to put data directories on NFS,
and even if we did tell them not to, they'd still do it. And NFS
locking is not trustworthy,
On Apr 13, 2011, at 11:37 PM, Tom Lane wrote:
A.M. age...@themactionfaction.com writes:
1. As long one keeps SysV shared memory around, the postgresql project
has to maintain the annoying platform-specific document on how to
configure the poorly named kernel parameters.
No, if it's just a
On Thu, Apr 14, 2011 at 10:26:33AM -0400, A.M. wrote:
1) the SysV nattch method's primary purpose is to protect the shmem
region. This is no longer necessary in my patch because the shared
memory in unlinked immediately after creation, so only the initial
postmaster and its children have
On Thu, Apr 14, 2011 at 7:26 AM, A.M. age...@themactionfaction.com wrote:
From what I understood, the primary purpose of the SysV check was to protect
the shared memory from multiple stompers. The interlock was a neat
side-effect.
Not really - the purpose of the interlock is to protect the
A.M. age...@themactionfaction.com writes:
On Apr 11, 2011, at 7:13 PM, Tom Lane wrote:
Robert Haas robertmh...@gmail.com writes:
I mean I'm not convinced that fcntl() locking will be as reliable.
I'm not either. Particularly not on NFS.
Is there an example of a recent system where fcntl is
On Apr 13, 2011, at 2:06 AM, Tom Lane wrote:
A.M. age...@themactionfaction.com writes:
On Apr 11, 2011, at 7:13 PM, Tom Lane wrote:
Robert Haas robertmh...@gmail.com writes:
I mean I'm not convinced that fcntl() locking will be as reliable.
I'm not either. Particularly not on NFS.
Is
On Wed, Apr 13, 2011 at 7:20 AM, A.M. age...@themactionfaction.com wrote:
The goal of this patch is to eliminate SysV shared memory, not to implement
NFS-capable locking which, as you point out, is virtually impossible.
As far as I can tell, in the worst case, my patch does not change how
Robert Haas robertmh...@gmail.com writes:
In answer to your off-list question, one of the principle ways I've
seen fcntl() locking fall over and die is when someone removes the
lock file. You might think that this could be avoided by picking
something important like pg_control as the log
On Apr 13, 2011, at 8:36 PM, Robert Haas wrote:
I don't see why we need to get rid of SysV shared memory; needing less
of it seems just as good.
1. As long one keeps SysV shared memory around, the postgresql project has to
maintain the annoying platform-specific document on how to configure
On Wed, Apr 13, 2011 at 6:11 PM, A.M. age...@themactionfaction.com wrote:
I don't see why we need to get rid of SysV shared memory; needing less
of it seems just as good.
1. As long one keeps SysV shared memory around, the postgresql project has to
maintain the annoying platform-specific
A.M. age...@themactionfaction.com writes:
1. As long one keeps SysV shared memory around, the postgresql project
has to maintain the annoying platform-specific document on how to
configure the poorly named kernel parameters.
No, if it's just a small area, I don't see that that's an issue.
On Sun, Apr 10, 2011 at 5:03 PM, A.M. age...@themactionfaction.com wrote:
To ensure that no two postmasters can startup in the same data directory, I
use fcntl range locking on the data directory lock file, which also works
properly on (properly configured) NFS volumes. Whenever a postmaster
On Apr 11, 2011, at 6:06 PM, Robert Haas wrote:
On Sun, Apr 10, 2011 at 5:03 PM, A.M. age...@themactionfaction.com wrote:
To ensure that no two postmasters can startup in the same data directory, I
use fcntl range locking on the data directory lock file, which also works
properly on
On Mon, Apr 11, 2011 at 3:11 PM, A.M. age...@themactionfaction.com wrote:
On Apr 11, 2011, at 6:06 PM, Robert Haas wrote:
On Sun, Apr 10, 2011 at 5:03 PM, A.M. age...@themactionfaction.com wrote:
To ensure that no two postmasters can startup in the same data directory, I
use fcntl range
Robert Haas robertmh...@gmail.com writes:
On Mon, Apr 11, 2011 at 3:11 PM, A.M. age...@themactionfaction.com wrote:
What do you mean by leakier? The goal here is to extinguish SysV shared
memory for portability and convenience benefits. The mini-SysV proposal was
implemented and shot down by
Robert Haas robertmh...@gmail.com writes:
On Sun, Apr 10, 2011 at 5:03 PM, A.M. age...@themactionfaction.com wrote:
To ensure that no two postmasters can startup in the same data directory, I
use fcntl range locking on the data directory lock file, which also works
properly on (properly
On Apr 11, 2011, at 7:25 PM, Tom Lane wrote:
Robert Haas robertmh...@gmail.com writes:
On Sun, Apr 10, 2011 at 5:03 PM, A.M. age...@themactionfaction.com wrote:
To ensure that no two postmasters can startup in the same data directory, I
use fcntl range locking on the data directory lock
On Apr 11, 2011, at 7:13 PM, Tom Lane wrote:
Robert Haas robertmh...@gmail.com writes:
On Mon, Apr 11, 2011 at 3:11 PM, A.M. age...@themactionfaction.com wrote:
What do you mean by leakier? The goal here is to extinguish SysV shared
memory for portability and convenience benefits. The
On Sat, Nov 13, 2010 at 08:07:52PM -0500, Tom Lane wrote:
A.M. age...@themactionfaction.com writes:
The goal of this work is to address all of the shortcomings of previous
POSIX shared memory patches as pointed out mostly by Tom Lane.
It seems like you've failed to understand the main
Martijn van Oosterhout klep...@svana.org writes:
The only real solution seems to me to be to keep a small SysV shared
memory segment for the locking and allocate the rest of the shared
memory some other way.
Yeah, that's been discussed. It throws all the portability gains out
the window. It
On Sun, Nov 14, 2010 at 11:06 AM, Tom Lane t...@sss.pgh.pa.us wrote:
Martijn van Oosterhout klep...@svana.org writes:
The only real solution seems to me to be to keep a small SysV shared
memory segment for the locking and allocate the rest of the shared
memory some other way.
Yeah, that's
The goal of this work is to address all of the shortcomings of previous POSIX
shared memory patches as pointed out mostly by Tom Lane.
Branch:
http://git.postgresql.org/gitweb?p=users/agentm/postgresql.git;a=shortlog;h=refs/heads/posix_shmem
Main file:
A.M. age...@themactionfaction.com writes:
The goal of this work is to address all of the shortcomings of previous POSIX
shared memory patches as pointed out mostly by Tom Lane.
It seems like you've failed to understand the main shortcoming of this
whole idea, which is the loss of ability to
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