On 4/13/15 8:54 AM, Jeremy Stanley wrote:
On 2015-04-13 04:03:49 -0400 (-0400), Victor Stinner wrote:
Great. Did you notice a performance regression?
Nope. Worth noting, we implemented it primarily for its lack of
compiled extensions, and to a lesser because it supports Python 3.x.
I suspect if we do later run into any unexpected performance
issues... well, it's pure Python. We have lots of people who can
help.
Mike wrote that PyMySQL is much slower than MySQL-Python.
right so it's all a question of proportionality. First off, some
major performance improvements have been merged into PyMySQL since I
wrote my wiki entry on it. Secondly, one thing I didn't do in that
wiki (the one here https://wiki.openstack.org/wiki/PyMySQL_evaluation)
do a performance test of MySQL-Python and PyMySQL talking to a
non-localhost database; as you can see in the RunSnake profiles I have
at
http://techspot.zzzeek.org/2015/02/15/asynchronous-python-and-databases/
the proportion of network takes up a lot more over the wire, and when
you compare MySQL-Python to PyMySQL in that sense the differences in
Python overhead vs. not become much less a proportion of the overhead
already.
Take both drivers and put them way deep into the very elaborate
operations we see Openstack DB backends doing and it's quite difficult
to observe differences qualitatively; unless you really did speed tests
for many thousands of identical operations on both. It's usually in
the "we tested how long it would take to do 10K or 100K rows /
operations / etc" space that differences like these add up. Which is
why, as is in my blog post, I take the stance that using things like
eventlet / gevent / async for database code in the first place is not
really worth the extra headaches at all, even if they did prove to be
faster than traditional threads, which also I show that they are in fact
not, for CRUD-style database code as we do in Openstack apps.
I don't recall him saying that specifically. Also last I recall he
admitted he hadn't actually tested under the sorts of load we would
drive in a production OpenStack service--merely performed some
fairly artificial benchmarks looping known-expensive operations that
may not ultimately reflect places in our codebase where introducing
any sort of slowdown would be noticeable compared to other
operations being performed.
Chances are the Project Infrastructure systems will continue
incrementally switching to PyMySQL mainly because it's easier to
install and works on a broader variety of platforms.
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