Multiprocessing process termination

[Sturla Molden]

Why not use a multiuser database server instead of trying to make one? You
do not have the resources to a better job on your own. You know where to
find Firebird SQL, MariaDB, MySQL, PostegreSQL, IBM DB2, Oracle, etc. 

Personally I prefer Firebird because like SQLite the database is stored in
a file. Another nice way to get the database in a file is to run it in an
Oracle VirtualBox VM.

SQLite also allows multiple connections, by the way, but it does not scale
very well. 

Regards,
Sturla


Charles Hixson <charleshixsn at earthlink.net> wrote:
> In order to allow multiple processes to access a database (currently 
> SQLite) I want to run the process in a separate thread.  Because it will 
> be accessed from multiple processes I intent to use Queues for shifting 
> messages back and forth.  But none of the individuals processes will 
> know when all of the others are through.  It there a way to properly 
> close the database, or does it need to be done from the parent process?
> 
> What I want to do is detect that a request to shutdown the Process has 
> been received, and then execute a close procedure that cleans things up 
> and shutdown.  Terminate is the obvious procedure to use, but that comes 
> with a warning not to use it if there is an queue attached (and without 
> defining attached).
> OTOH, since the queue will never be read after the process has been 
> shutdown, perhaps rendering it unusable is the proper thing.
> 
> Could someone comment on this step of the design?
> 
> The basic idea is:
> 
> class handledb(Process):
>     def __init__(self, q, otherstuff):
>         self.q  =  q
> 
>    def run(self, msg):
>       while (true):
>           if  self.q.empty():
>               sleep(someamountoftime)
>           else:
>               while (not self.q.empty()):
>                     read and parse message
>                     if message says to shutdown:  self.shutdown()
> 
>    def  shutdown(self):
>          close things down
>          ?? terminate ??                    <<-- should this be done 
> while q is live?