DB API and thread safety

[Robin Haswell]

Hey guys

I've been reading http://www.python.org/peps/pep-0249.html and I don't
quite get what level of thread safety I need for my DB connections.

If I call db = FOOdb::connect() at the start of my app, and then every
thread does it's own c = db.cursor() at the top, what level of thread
safety do I need to avoid threads stepping on each other? Hopefully the
answer to this question will get me oriented enough to understand the
other options

Cheers

-Rob

 

[Matt Goodall]

Hey guys

I've been reading http://www.python.org/peps/pep-0249.html and I don't
quite get what level of thread safety I need for my DB connections.

If I call db = FOOdb::connect() at the start of my app, and then every
thread does it's own c = db.cursor() at the top, what level of thread
safety do I need to avoid threads stepping on each other? Hopefully the
answer to this question will get me oriented enough to understand the
other options

Assuming the cursor created in the thread is never accessed by another
thread then you need a dbapi module that supports threadsafety level 2 -
"threads may share the module and connections".

- Matt

--
__
/ \__ Matt Goodall, Pollenation Internet Ltd
\__/ \ w: http://www.pollenation.net
__/ \__/ e: (e-mail address removed)
/ \__/ \ t: +44 (0)113 2252500
\__/ \__/
/ \ Any views expressed are my own and do not necessarily
\__/ reflect the views of my employer.

 

[Daniel Dittmar]

Hey guys

I've been reading http://www.python.org/peps/pep-0249.html and I don't
quite get what level of thread safety I need for my DB connections.

If I call db = FOOdb::connect() at the start of my app, and then every
thread does it's own c = db.cursor() at the top, what level of thread
safety do I need to avoid threads stepping on each other? Hopefully the
answer to this question will get me oriented enough to understand the
other options

Even if you can share the connection between threads, it will be the
rare database which can actually work concurrently on one connection.
Most drivers promising "threads may share the module and connections"
will use a lock so that only one operation is active at a time.

For maximum throughput (at the cost of using more ressources on the
database), you'd use one connection per thread. If you want to use
transactions, then it is the only way.

Daniel