Hey!
I’m using ActiveRecord with an SQLite Database.
It works great, but has one drawback. SQlite does’nt support multiple
connection at one time.
Is there a mathod to synchronize ActiveRecord calls over different
threads?
thx CK
google for activerecord multi threaded
I think it has something to do with allow_concurrency.
-R
On Mon, May 5, 2008 at 6:47 AM, Christian K.
Roger P. wrote:
google for activerecord multi threaded
I think it has something to do with allow_concurrency.
-ROn Mon, May 5, 2008 at 6:47 AM, Christian K.
Hmmm doesn’t work form me. I still get a “busy-Exception”.
Other options?
thx
allow_concurrency “allows conconcurrency” on the connection (as
opposed to the database), so 2 threads can execute on the same
connection. If you’re trying to have 2 applications read from the
same database (like having a script/runner do database stuff in the
background while your server runs), this is simply not possible.
Because SQLite effectively uses a flat-file, there is no way to have
more than 1 connection to the same database – there is no way for one
connection to know what the other is doing so as to avoid concurrent
modifications resulting in data corruption.
On May 5, 9:39 am, Christian K. [email protected]
tekwiz wrote:
allow_concurrency “allows conconcurrency” on the connection (as
opposed to the database), so 2 threads can execute on the same
connection. If you’re trying to have 2 applications read from the
same database (like having a script/runner do database stuff in the
background while your server runs), this is simply not possible.
Because SQLite effectively uses a flat-file, there is no way to have
more than 1 connection to the same database – there is no way for one
connection to know what the other is doing so as to avoid concurrent
modifications resulting in data corruption.
i would need a queuing mechanism, that executes queries fifo.
Wouldn’t it be possible to achieve such a behaviour with a mutex, that
synchronizes access to activerecord’s save and destroy methods?
ck
On 5 May 2008, at 16:56, Christian K. wrote:
connection to know what the other is doing so as to avoid concurrent
modifications resulting in data corruption.i would need a queuing mechanism, that executes queries fifo.
Wouldn’t it be possible to achieve such a behaviour with a mutex, that
synchronizes access to activerecord’s save and destroy methods?
Not if you’re talking about separate mongrels (or rails instance of
any sort). But doesn’t sqlite allow enough concurrency
(File Locking And Concurrency In SQLite Version 3
) ?
Fred
Yes, your fifo/mutex concept is correct. You just have to ensure that
2 active record instances don’t attempt to play with the database at
the same time.
On May 5, 11:06 am, Christian K. [email protected]
Frederick C. wrote:
On 5 May 2008, at 16:56, Christian K. wrote:
connection to know what the other is doing so as to avoid concurrent
modifications resulting in data corruption.i would need a queuing mechanism, that executes queries fifo.
Wouldn’t it be possible to achieve such a behaviour with a mutex, that
synchronizes access to activerecord’s save and destroy methods?Not if you’re talking about separate mongrels (or rails instance of
any sort). But doesn’t sqlite allow enough concurrency
(File Locking And Concurrency In SQLite Version 3
) ?Fred
I have one Ruby Process, that runs two threads.
In one of them runs a webrick server, one is a background task. Both
threads operate on the same database.
I’ve done a quick prototype with a mutex and i seems to work; no more
busy exceptions.
I still have to dig a bit deeper.
You are correct that SQLite3 does provide “enough” concurrency;
however, the active record decides to pitch a hissy-fit, throwing
exceptions, when it encounters a locked db rather than waiting and
trying again for a certain period.
On May 5, 11:01 am, Frederick C. [email protected]