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gnu_D

Member

From: Macedonia

Registered: 2007-10-21

Posts: 46

SQLIte in python, using an instance of a database in threads.

Hi, I got a Database manager, it starts in background and waits someone to call add_task, when it does, the ask then is executed, and the content is then applied in the db.

But it raises an error, says:

ProgrammingError: SQLite objects created in a thread can only be used in that same thread.The object was created in thread id -1218516784 and this is thread id -1223136400

This is the code: http://paste.pocoo.org/show/252409/

P.S: If someone can tell me where can I find some module which does that for me, for instance wait in the background for tasks.

Edit: typo .

Last edited by gnu_D (2010-08-20 13:43:54)

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simlan

Member

From: Germany

Registered: 2010-05-30

Posts: 20

Re: SQLIte in python, using an instance of a database in threads.

A nice database handler: Sqlalchemy (http://www.sqlalchemy.org/)
Read the docs, there are examples how to manage threading and connection pooling.

Here is a specific section on threading:

http://www.sqlalchemy.org/docs/referenc … g-behavior

It does also clarifiy how to make your programm threadsafe.

Last edited by simlan (2010-08-26 06:26:35)

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gnu_D

Member

From: Macedonia

Registered: 2007-10-21

Posts: 46

Re: SQLIte in python, using an instance of a database in threads.

Actually I tried, but the same thing happend.
So I left it be .

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cactus

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From: t͈̫̹ͨa͖͕͎̱͈ͨ͆ć̥̖̝o̫̫̼s͈̭̱̞͍̃!̰

Registered: 2004-05-25

Posts: 4,622

Website

Re: SQLIte in python, using an instance of a database in threads.

sqlite does not work well (at all?) with threaded / multiproc code accessing one database, unless you handle locking yourself. Just dont do it.

http://www.sqlite.org/faq.html#q5
http://www.sqlite.org/faq.html#q6  (note the section on specific compilation options)

If you need db access, and you need threading, I recommend you use some type of locking singleton that receives messages from worker threads, ala Actors or something.

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Mr.Elendig

#archlinux@freenode channel op

From: The intertubes

Registered: 2004-11-07

Posts: 4,094

Re: SQLIte in python, using an instance of a database in threads.

The other obligatory question is: Why threads? With python threads you can't run more than one task at a time anyway.

You might want to consider some async lib ala twisted instead.

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