DEV: Jak na zamek na databazi?

[Pavel Kankovsky]

On Wed, 26 Mar 2003, Stanislav Meduna wrote:

> On Wed, 26 Mar 2003 18:15:39 +0100, Jan Kubik wrote:
> 
> : fcntl ... locking na soubor, ktery ma tolik Byte, jake je max. mozny
> : pocet procesu
> 
> Teoria pekna, prax zial na Linuxe nefunguje medzi threadmi,
> iba medzi procesmi.

TOG Base Specification Issue 6 zasadne spojuje zamky s procesem a nikoli
threadem, napr.:

   Before a successful return from an F_SETLK or an F_SETLKW request when
   the *calling process* has previously existing locks on bytes in the
   region specified by the request, the previous lock type for each byte
   in the specified region shall be replaced by the new lock type.

> Samozrejme su vynimky. Pokial su tie thready pomerne oddelene
> a komunikuju cez uzke rozhranie (napr. jeden spracovatelsky
> thread, jeden UI, informacie si posielaju cez nejaku dobre
> definovanu frontu a inak si navzajom do dat nelezu), tam
> toho az tolko pokazit nejde.

To pak lze udelat stejne dobre misto threadu udelat fork(). :)
Privolavat si boleni hlavy z threadu ma smysl prave a pouze v pripade,
ze se opravdu vyuzije to, ze sdileji jeden pametovy prostor (pripadne
dalsi veci jako otevrene soubory).

--Pavel Kankovsky aka Peak  [ Boycott Microsoft--http://www.vcnet.com/bms ]
"Resistance is futile. Open your source code and prepare for assimilation."