It looks like iterating over the db result object is what's causing
the slowdown.
With a small result set (20 records), here are the times in 0.31 to do
the db query and to render xml by iterating over the result object:
db: 0.01993 second
render: 0.00087 second
total: 0.02671 second
Then with a large result set (17,142 records):
db: 0.09306 second
render: 67.98967 seconds
total: 68.08277
On version 0.23 and the large result set (17,142 records):
db: 0.06552
render: 0.16659
total: 0.23248
Clearly the render function is the problem. This function takes the
db result object as a parameter, and iterates over it to create the
xml:
def render_xml(items):
xml = '<?xml version=\"1.0\"?>\n'
xml += '<rootnode>\n'
for item in items:
xml += '<itemnumber>%s</itemnumber>\n' % item.id
xml += '<description>%s</description>\n' % item.descr
xml += '<quantity>%s</quantity>\n' % item.qty
...
return xml
dbresult = db.query(querystring)
return render_xml(dbresult)
On Jan 1, 8:04 pm, "Aaron Swartz" <[email protected]> wrote:
> Can you share more details? Code? Profiler output?
>
> On Jan 1, 2009 10:55 PM, "mb" <[email protected]> wrote:
>
> I have a web service that queries a database and returns a fairly
> large xml document based on parameters in the URL.
>
> This morning, with web.py 0.23, it would return a 17,142 line response
> (491k) in 200 ms.
>
> This afternoon I upgraded to 0.31, and it now takes 56 seconds for the
> same action.
>
> For the entire 56 seconds, the cpu is pegged at 100% on the python
> process with just one request, where on 0.23 I could run many
> simultaneous requests and the cpu was rarely over 40%.
>
> Any ideas why my performance has dropped by a factor of 300?
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