[Opensim-dev] Lockless Lists?

[Frisby, Adam]

Please! Not while there are children about!

Adam

> -----Original Message-----
> From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev-
> bounces at lists.berlios.de] On Behalf Of Tedd Hansen
> Sent: Tuesday, 2 December 2008 2:38 PM
> To: opensim-dev at lists.berlios.de
> Subject: Re: [Opensim-dev] Lockless Lists?
>
> I was thinking in the lines of
> perl -pi -e '
> s/Monitor(?<=\.(Enter|Exit))/global::MyCool.ThreadMon/gs;
> s/(?![a-zA-Z0-9])Lock(?<=\s+\()/global::MyCool.ThreadLok/gs;
> ' *
>
> (not committing change)
> LockTimes method is of course a bit more sophisticated (and exact). :)
>
> -----Original Message-----
> From: opensim-dev-bounces at lists.berlios.de
> [mailto:opensim-dev-bounces at lists.berlios.de] On Behalf Of Hurliman,
> John
> Sent: 2. desember 2008 21:42
> To: opensim-dev at lists.berlios.de; homer.horwitz at gmail.com
> Subject: Re: [Opensim-dev] Lockless Lists?
>
> LockTime already provides the second feature. The first could be
> implemented by replacing Monitor.Enter() calls with
> Monitor.TryEnter(200) and printing out an error if that returns false.
> Easier to modify the bytecode with a program than replace all of the
> locks in the source code.
>
> My post on LockTime is up now at
> http://software.intel.com/en-us/blogs/2008/12/02/timing-locks-in-c/
>
> John
>
> > -----Original Message-----
> > From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev-
> > bounces at lists.berlios.de] On Behalf Of Tedd Hansen
> > Sent: Monday, December 01, 2008 9:38 AM
> > To: opensim-dev at lists.berlios.de; homer.horwitz at gmail.com
> > Subject: Re: [Opensim-dev] Lockless Lists?
> >
> > Hi
> >
> > You could create your own implementation of lock and mutex commands,
> > and do all solution wide replacement of all their usages.
> > Then use these custom implementations to identify deadlock
> situations.
> > Using these you could also time how long each lock lasts, and print
> > some debug containing "StackFrame.GetFrame().GetMethod().Name" when
> > lock exceeds a certain time span.
> > Should give a fairly good picture of trouble spots. :)
> >
> > - Tedd
> >
> > -----Original Message----- From: opensim-dev-bounces at lists.berlios.de
> > [mailto:opensim-dev-bounces at lists.berlios.de] On Behalf Of Hurliman,
> > John Sent: 26. november 2008 02:19 To: opensim-dev at lists.berlios.de;
> > homer.horwitz at gmail.com Subject: Re: [Opensim-dev] Lockless Lists?
> >
> >
> >
> > -----Original Message----- From: opensim-dev-bounces at lists.berlios.de
> > [mailto:opensim-dev-bounces at lists.berlios.de] On Behalf Of
> Christopher
> > Yeoh Sent: Tuesday, November 25, 2008 3:26 PM To:
> > homer.horwitz at gmail.com; opensim-dev at lists.berlios.de Subject: Re:
> > [Opensim-dev] Lockless Lists?
> >
> > On Mon, 24 Nov 2008 20:43:09 +0100
> > "Homer Horwitz" <homerhorwitz at googlemail.com> wrote:
> >>
> >> So, I'm not sure if we really should do that move. If at all, I'm
> >> for a very slow move to lock-free versions from a rather stable
> >> software base (which we currently don't have in trunk), so errors
> >> that are introduced during that move are more easily identifiable,
> >> with much testing in-between. Even then, I'm absolutely sure we will
> >> get a lot of Heisenbugs in the process, which will take us weeks to
> find.
> >>
> >
> > Perhaps what is really needed here is some performance benchmarks
> > which highlight existing problems? So for individual changes to
> > lockless versions we better see what improvements we'd get on both
> > small and large SMP machines and whether its worth the increase in
> complexity.
> >
> > I did some debugging of a deadlock a couple of weeks ago and found it
> > already pretty complicated. Any suggestions on how other people
> approach
> > these problems with OpenSim? I sprinkled lots of console messages
> around
> > as mdb doesn't seem to work for me, but in retrospect it would have
> been
> > really handy to have been able to just turn on a lock debugging flag
> and
> > have debug output when locks are taken and released.
> >
> > Regards,
> >
> > Chris
> >
> >
> >
> > One idea I've tossed around is using Mono.Cecil to inject some code
> > for profiling locks. Since
> >
> > lock (lockObject)
> > {
> >         ...
> > }
> >
> > Gets expanded out by the compiler to:
> >
> > Monitor.Enter(lockObject);
> > try
> > {
> >         ...
> > }
> > finally
> > {
> >         Monitor.Exit(lockObject);
> > }
> >
> > It shouldn't be too difficult to follow up any Monitor.Enter() calls
> > by storing current ticks, and do a check in the finally if current
> > ticks - stored ticks > lock_warn_const. Then we could scan any binary
> > for long- held locks.
> >
> > John _______________________________________________ Opensim-dev
> mailing
> > list Opensim-dev at lists.berlios.de
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