Re: [Tcl-tdbc] tdbc::mysql and multiple threads...

[Georgios P. <pet...@ya...>]

Dear Donal,

At least one of the TODOs (the one with the thread init) is not a 
pressing issue, as mysql_init() will also
call  mysql_thread_init(), according to the manual. I am not sure 
whether it is called more than one though.
(I think that each new connection will call mysql_init()).

In my code, the connection creation (or the connection close) is not 
protected by a mutex. I will try to change this and see what happens.

Regards,

George

On 2/9/2016 14:49, Donal K. Fellows wrote:
> On 02/09/2016 12:11, to...@tu... wrote:
>> Given what you write, it might be some part of tdbc (perhaps the *dbc
>> library?) isn't thread safe?
>
> The core of TDBC is thread-agnostic in the usual Tcl way; it's just 
> bound to an interpreter. If there is a problem, it's in the 
> tdbc::mysql driver package. If we look at the code:
>
> http://core.tcl-lang.org/tdbcmysql/artifact/47de19173a3e0d14?ln=1296-1306
>
> ... I might wonder based on the comment whether there is a problem. 
> There might be, but I don't know the mysql client library. Once open, 
> I'd expect connections to be interpreter-bound; that's how all of TDBC 
> is designed to work. (Heh, scanning through the code overall indicates 
> three places with “TODO” that might indicate something relevant, but I 
> don't know for sure.)
>
> I assume that if you put the actual connection creation guarded by a 
> mutex, which you can do easily enough from user code via the 
> primitives in the Thread package (i.e., you can check without changing 
> or recompiling the tdbc::mysql code), everything else after that will 
> work as well as the DB permits.
>
> Donal.
>
>
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