[elephant-devel] DB migration issue

[Ian Eslick]

Hi Quan,

Can you try the latest darcs with BDB 4.6 or 4.7?  I made some changes  
to migration, but I can't recall if they were in the latest darcs or  
not - I think the latest darcs doesn't play well with BDB 4.5 so  
please make sure you can reproduce under the above configuration if  
you can.

Thank you,
Ian

On Dec 29, 2008, at 3:40 AM, quan hu wrote:

> Hello,
>
>      I run into a problem when doing the garbage collection via data  
> migration.
>      The environment is elephant 0.9.1 and BDB 4.5.  I also tried  
> the latest elephant in darc and get the same result.
>
>      1.  Test case to reproduce the problem.
>
>            (defpclass user-profile()
>              ((id :initform nil :index t)
>              (sms-inbox  :initform (make-pset))))
>
>             ;; Create a new db for test purpose
>            (setf *migrate-src* (open-store '(:bdb "/tmp/db/src/")))
>            (setf *test-obj* (make-instance 'user-profile :sc  
> *migrate-src*))
>             (insert-item 'foo (slot-value *test-obj* 'sms-inbox))
>             (setf *migrate-dst* (open-store '(:bdb "/tmp/db/dst/")))
>
>           TEST> (migrate *migrate-dst* *migrate-src*)
>               Migrating class indexes for: USER-PROFILE
>            ; => Input get blocked, not response anymore
>
>        2.  Using "db_stat -C A" get following output:
>              1    Lock requests not available due to conflicts, for  
> which we waited
>
>        3.  I do some debug work and found the problem may be caused  
> by nested transaction of different store controller.
>             I can reproduce the issue with following code segment
>
>           TEST> (ensure-transaction (:store-controller *migrate-dst*)
>                             (add-to-root 'foo 'foo :sc *migrate-dst*)
>                             (ensure-transaction (:store-controller  
> *migrate-src*)
>                                  (add-to-root 'bar 'bar :sc *migrate- 
> dst*)))
>
>              This kind of nested transaction scenario can appear in  
> the migrate process, because it uses source/destination store  
> controller at the same time.
>
>             I do not understand why different store controller's  
> transaction can result in the lock conflict and want to know how to  
> fix it.
>
>             Is there anyone meet the similar problem before?
>
> Thanks
> Quan
>
>
>
>
>
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