Re: [Firebird-devel] Max transaction duration

[David J. <dav...@di...>]

On 2002.12.13 04:21:59 -0500 Pavel Cisar wrote:
> Sean,
> 
> On 12 Dec 2002 at 19:48, Leyne, Sean wrote:
> 
> > At this point, I think should remind everyone that the request was for
> > the *ability* to set a transaction timeout value.
> > 
> > Nothing was ever said to suggest by enabling this feature, that the
> > engine would by 'default' start closeing connections.
> > 
> > I think of this as equivalent to Nickolay's new explicit locking
> feature
> > in v1.5.  It's there, if you don't want to use, fine no one is going to
> > force you to.  but if it helps deal with a bad software/problem (maybe
> > you don't have the source), what's the harm?
> 
> Well, but how about the code bloat and new potential points of failure ? 
> The small footprint and compact code and behaviour is one from major FB 
> features that are easy to lose, but hard to achieve.
> 
> I have nothing against new features, if they are reasonable. For me, 
> "reasonable" means (at least) one point from:
> 
> 1) Satisfy a general requirement

Timeouts seem to be a general requirement for reliable distributed system
design.  I havne't seen any attempts to design a reliabe distributed system
that don't use either an explicity timeout (xa distributed transaction
model, JINI) or an implicit timeout (heartbeat, ping).  It is certainly an
explicit requirement of the xa transaction model.
> 
> 2) Satisfy an occasional requirement of many that's hard to achieve by 
> other ways effectively
> 
> 3) Satisfy general requirement of few that's hard to achieve by other 
> ways effectively
> 
> The transaction timeout seems to fall in third category, but I'm not 
> convinced that it's not doable effectively "outside the engine".

Since, as noted above, all designers of reliable distributed systems seem
to rely on timeouts to determine remote node failures, I think it's up to
you to demonstrate that there are other solutions that provide the same
degree of automatic recovery from remote failure.

Firebird seems to be the only open source database that supports 2pc and
can be maneuvered into supporting almost all of xa: therefore IMO it's the
only plausible open source choice to use in j2ee apps with more than one
resource manager.  I don't really understand the point of arguing against
industry standard features for this environment.

I would have asked for this feature a long time ago if I had fully
appreciated the role of timeouts in reliability.  As it is, I only really
started to appreciate it when working on making the jboss transaction
manager recoverable.

thanks
david jencks
> 
> Best regards
> Pavel Cisar
> http://www.ibphoenix.com
> For all your upto date Firebird and
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> 
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