Status of Python threading support (GIL removal)?
jure.erznoznik at gmail.com
Sat Jun 20 21:23:50 EDT 2009
Look, guys, here's the thing:
In the company I work at we decided to rewrite our MRP system in
Python. I was one of the main proponents of it since it's nicely cross
platform and allows for quite rapid application development. The
language and it's built in functions are simply great. The opposition
was quite strong, especially since the owner cheered for it - .net.
So, recently I started writing a part of this new system in Python. A
report generator to be exact. Let's not go into existing offerings,
they are insufficient for our needs.
First I started on a few tests. I wanted to know how the reporting
engine will behave if I do this or that. One of the first tests was,
naturally, threading. The reporting engine itself will have separate,
semi-independent parts that can be threaded well, so I wanted to test
The rest you know if you read the two threads I started on this group.
Now, the core of the new application is designed so that it can be
clustered so it's no problem if we just start multiple instances on
one server, say one for each available core.
The other day, a coworker of mine said something like: what?!? you've
been using Python for two days "already" and you already say it's got
a major fault?
I kinda aggreed with him, especially since this particular coworker
programmed strictly in Python for the last 6 months (and I haven't due
to other current affairs). There was no way my puny testing could
reveal such a major drawback. As it turns out, I was right. I have
programmed enough threading to have tried enough variations which all
reveal the GIL. Which I later confirmed through searching on the web.
My purpose with developing the reporting engine in Python was twofold:
learn Python as I go and create a native solution which will work out-
of-the-box for all systems we decide to support. Making the thing open
source while I'm at it was a side-bonus.
Since the testing revealed this, shall we say "problem", I am tempted
to just use plain old C++ again. Furthermore, I was also not quite
content with the speed of arithmetic processing of the python engine.
I created some simple aggregating objects that only performed two
additions per pass. Calling them 200K times took 4 seconds. This is
another reason why I'm beginning to think C++ might be a better
alternative. I must admit, had the GIL issue not popped up, I'd just
take the threading benefits and forget about it.
But both things together, I'm thinking I need to rethink my strategy
I may at some point decide that learning cross platform programming is
worth a shot and just write a Python plugin for the code I write. The
final effect will be pretty much the same, only faster. Perhaps I will
even manage to get close to Crystal Reports speed, though I highly
doubt that. But in the end, my Python skill will suffer. I still have
an entire application (production support) to develop in it.
Thanks for all the information and please don't flame each other.
I already get the picture that GIL is a hot subject.
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