[elephant-devel] DB_LOCK_DEADLOCK support

[Ian Eslick]

You can run a thread which aborts threads that otherwise would have  
hung.

"The DB_ENV->failchk method can now abort transactions for threads,  
which have failed while blocked on a concurrency lock. This  
significantly decreases the need for database environment recovery  
after thread of control failure. [#15626]"

My understanding is that you have to launch a thread to perform these  
checks and cause the transactions to abort (this requires true multi- 
threading - Allegro for example would not benefit from this since it  
still uses a semi-cooperative multitasking to avoid all locking that  
has been put into SBCL).

I've made some code changes in elephant-unstable to support 4.7 but  
had some bugs getting it running (problems with constants, API  
changes) but haven't had the chance to track the errors down.  I won't  
be doing any more elephant development until at least mid-September.

I am aware that there is a reasonable set of issues with various  
lisps, an intermittent de-serializer bug that also shows up in stable,  
and a condition that requires restarting the db when I kill stuck  
threads that are in the middle of a transaction...

Ian


On Aug 28, 2008, at 10:04 AM, Leslie P. Polzer wrote:

>
> Is it correct that db4.7 has built-in deadlock detection,
> and elephant-unstable has been adapted to that?
>
>  Leslie
>
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