[elephant-devel] SQLite locking error / BDB multi-image support

[Ian Eslick]

Hmmm...I believe that only the first to connect should attempt recovery.

Much of these issues are BDB restrictions that one has to live with if  
you want to do more than the basic thing with them.  It would be  
worthwhile for you to read up on BDB if you want to do the multi- 
process implementation.  I don't know of anyone who has fully charted  
this territory and elephant certainly doesn't have specific features  
to help you deal (although you can launch a background db_deadlock  
process to free deadlocked threads/processes with an argument to open- 
store on your master process).

Using the described patch I was able to have two writers, one from an  
Allegro image and one from an SBCL image both hammering (reading/ 
writing) on the same set of objects similar to your example.

By mess up the other process I assume you are running into a crash of  
some kind and not data corruption (i.e. transaction design) issues

Ian

PS - Make sure you force a rebuild anytime you update.  I've found  
asdf doesn't always get it right.


On Feb 26, 2008, at 1:42 PM, Leslie P. Polzer wrote:

>
>> I just pushed a patch that should automatically manage two processes
>> connecting to the same environment.  You typically have to coordinate
>> who is the master user and who is the slave so that you don't try to
>> recover an environment that is already in use by another process.
>> This causes that first process to fail, I believe, because it
>> discovers it's pointers into the environment are 'corrupted'.
>
> Doesn't do it for me. Opening two stores is fine, and I believe even
> reading. But writing messes the other process up.
>
> Without attempting recovery, everything seems to be fine.
> I must live with that for now, since I ran out of backend choices...
>
>  Leslie
>
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