Re: Lock-free databases
Date: 9 Nov 2005 06:58:01 -0800
Message-ID: <1131548281.495758.63230_at_o13g2000cwo.googlegroups.com>
Joe Seigh wrote:
> VC wrote:
> > "Joe Seigh" <jseigh_01_at_xemaps.com> wrote in message
> > news:r4mdnWBDc5K56ezenZ2dnUVZ_v6dnZ2d_at_comcast.com...
> >
> >>VC wrote:
> >>
> >>>"Mark D Powell" <Mark.Powell_at_eds.com> wrote in message
> >>>news:1131475590.080140.136430_at_g47g2000cwa.googlegroups.com...
> >>>
> >>>"ANTs 3.2 is also the only lock-free relational database management
> >>>system architected for popular 64-bit Linux operating system
> >>>implementations running on AMD Opteron and Intel Xeon platforms. The ANTs
> >>>Data Server sets a new precedent in the database industry, allowing large
> >>>OLTP, real-time analytical processing and enterprise reporting to run
> >>>concurrently in the same server. "
> >>>
> >>>http://www.ants.com/index.php?option=com_content&task=view&id=437&Itemid=29
> >>
> >>Saying you're lock free isn't the same as being lock-free.
> >
> >
> > You may have a point, or you may not. You just don't know whether their
> > lock-free implentation helps the performance. They claim it does:
> >
> > "The second interesting thing about ADS is that ANTs claims that it
> > typically runs 5 to 15 times faster than standard relational databases. The
> > fact that it offers a lock-free environment is one reason for this" (
> > http://www.it-director.com/article.php?articleid=12912 )
> >
> > So why not give them the benefit of the doubt ? Did you run tests that
> > would indicate their claims are false ?
>
> I'm not saying their claims are false. But I'm not the one engaging
> in market hyperbole. The burden of proof is on them. They haven't
> provided any facts significant to anyone familiar with lock-free
> programming techniques.
>
> Lock-free techniques similar to the ones covered by their patents have
> be used in operating system kernels for decades and those operating systems
> weren't going around proclaiming they were lock-free.
> In fact use of lock-free
> techniques like RCU for significant performance benefits doesn't qualify
> Linux as lock-free since it still has plenty of locks left over.
>
> >
> >
> >>Unless
> >>their bottlenecks are IPC related, I don't see how their lock-free
> >>patented techniques would help performance.
> >
> >
> > There is some evidence (
> > http://www.cs.chalmers.se/~phs/TechnicalReports/SunT02_Noble.pdf ) that
> > operations on lock-free data structures outperform similar lock-based
> > implementations (without dragging IPC into the picture).
>
> Under certain conditions. It helps if you have contention. In non-contention
> cases, regular locks are as fast or faster than lock-free based solutions.
It may be true for RCU, but not true for other approaches to
implementing lock-free data structures (you can easily find plenty of
research results by googling for "performance" and "lock-free").
Clearly, in some cases lock-based synchronization will outperform
lock-free algorithms, no one claims otherwise.
> Having stuff lock-free doesn't automatically make things run faster.
>
> The reason I posted the OP was to find out if certain types of databases had
> enough contention to make it feasible to look into lock-free solutions. But
> that is more of a database internals question and most of the discussion here
> seems more focused on database externals.
Well, issues are pretty similar, whether one talk about synchronizing access to rows or internal memory structures.
>
>
> --
> Joe Seigh
>
> When you get lemons, you make lemonade.
> When you get hardware, you make software.
Received on Wed Nov 09 2005 - 15:58:01 CET