Re: [gnome-db] Threads.

On Fri, 2009-07-24 at 13:51 +0200, Vivien Malerba wrote:

> 
> 
> 
> 2009/7/24 Bas Driessen <[email protected]>
> 
>         Hello,
>         
>         Question regarding libgda and threads.
>         
>         I open a data source connection (ie:
>         gda_connection_open_from_dsn) in thread 1 and then I try to
>         perform any action on the connection (ie:
>         gda_connection_statement_execute_select) in thread 2. If I do
>         this in Postgresql all works fine. If I try to do this in
>         MySQL then the system appears to hang in thread 2. I assume
>         because thread 1 is holding a lock on the connection. 
>         
>         How can I remove the lock that is set by function
>         gda_connection_open_from_dsn so I can access the connection
>         information from thread 2?
>         
>         Perhaps slightly out of libgda scope, but is there a
>         difference between Postgresql and MySQL when it comes to
>         threads and locking? It appears that Postgresql does not have
>         that concept or perhaps by default configured not to use
>         threads?
>         
> 
> The same kind of limitation also applies to PostgreSQL which is
> usually not compiled with thread support in client libraries. The
> discrepancies between databases' client libraries regarding threads
> have led me to create the GDA_CONNECTION_OPTIONS_THREAD_SAFE flag (in
> 4.1, not in 4.0) where a connection can be used by any thread,
> regardless of the thread which created the connection (in fact a
> thread is created per connection and the user threads synchronize with
> that thread when running statements, it relies on the GdaThreadWrapper
> object).


My previous message crossed this one. So if I understand correctly,  in
fact my Postgresql is NOT thread safe and therefore it is working and
the MySQL IS thread safe and therefore it is "hanging" on a lock.

How/where can I set this GDA_CONNECTION_OPTIONS_THREAD_SAFE flag in 4.1?

Is there any workaround/solution in 4.0? Any chance to add this flag in
4.0 or will that break any API rules etc?

Thanks,
Bas.

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