[elephant-devel] Dropping DB connection during writes

[Tayssir John Gabbour]

Hi Ian,

The problem is, suppose I just open a store controller at the very
beginning. If I execute either of the following:

(sb-thread:make-thread
  (lambda ()
    (get-value "foobar"
               (get-from-root *my-btree-name*
                              :sc *my-store-controller*))))

(sb-thread:make-thread
  (lambda ()
    (get-value "foobar" *my-btree*)))


there's a new connection in the database, never dying and eventually
overflowing Postgresql's limit. (That is, "select count(*) from
pg_stat_activity;" has a new row each time). A couple DB people at
work looked at the ele-postmodern code, and they say they don't see
the connection being closed down.

I must be doing something wrong, but I can't see where...


All the best,
Tayssir



Ian Eslick wrote:
> with-open-store closes the store when you're done, null'ing out *store-
> controller*.  With sufficient concurrency you are likely to get a race
> condition where the if stmt in with-city-store succeeds but the body
> fails since you aren't locking access to *store-controller*.
>
> Ian
>
>
> On Nov 20, 2008, at 11:16 AM, Tayssir John Gabbour wrote:
>> Hi!
>>
>> With Elephant under both Postmodern and CLSQL, I'm consistently losing
>> my DB connection. This apparently happens when writing from fairly
>> simultaneous threads. (Two threads may write to the same btree key at
>> around the same time.)
>>
>> All I do is add objects to a BTree, keyed by their UUID. (And there's
>> two simple indexes.) No persistent metaclasses or anything; I just use
>> it as a persistent table.
>>
>> Am I doing something terribly wrong? Code and error messages at the
>> end of this email.