[IronPython] Exception Performance

[Cory Brostowicz]

Thanks for the suggestion using System.Double.TryParse, this brought my
performance metric back up.  Here is a dump of some internal instrumentation
inside my C# application that is making calls to the IronPython script
engine.  Values are expressed in exponential notation measuring
milliseconds.

Edit: SetProviderType           Count: 104851  Min: 1.654300E+000 Max:
6.401880E+001 Total: 1.829214E+005
Edit: SetFeeSchedule            Count: 104851  Min: 1.998300E+000 Max:
9.119120E+001 Total: 2.548539E+005

The SetFeeSchedule script was the one I was working on.  Previously, this
was showing a total value that was in the 6th power (around 15 minutes).
 This change now executes the script in a quarter of the time.

Thanks again,
Cory

On Tue, Aug 3, 2010 at 12:24 PM, Dino Viehland <dinov at microsoft.com> wrote:

> I think we still need to make sure that a call to float (and other numeric
> primitives) uses light weight exceptions as well for this scenario to
> completely
> be fast but that should be pretty easy.
>
> > -----Original Message-----
> > From: users-bounces at lists.ironpython.com [mailto:users-
> > bounces at lists.ironpython.com] On Behalf Of Dave Fugate
> > Sent: Tuesday, August 03, 2010 10:03 AM
> > To: Discussion of IronPython
> > Subject: Re: [IronPython] Exception Performance
> >
> > Yup, I think you'll find the situation in IronPython 2.7A1 to be a bit
> better
> > in this respect:
> >       D:\rft\vsl\dlr\bin>type blah.py
> >       from System.Diagnostics import Stopwatch
> >       t = Stopwatch()
> >
> >       try:
> >           t.Start()
> >           x = 1/0
> >       except Exception, e:
> >           t.Stop()
> >
> >       print t.Elapsed.TotalMilliseconds
> >
> >       D:\rft\vsl\dlr\bin>"C:\Program Files (x86)\IronPython 2.6\ipy.exe"
> > blah.py
> >       2.6096
> >
> >       D:\rft\vsl\dlr\bin>"C:\Program Files (x86)\IronPython 2.6\ipy.exe"
> > blah.py
> >       2.4518
> >
> >       D:\rft\vsl\dlr\bin>"C:\Program Files (x86)\IronPython 2.6\ipy.exe"
> > blah.py
> >       2.4622
> >
> >       D:\rft\vsl\dlr\bin>"C:\Program Files (x86)\IronPython 2.7\ipy.exe"
> > blah.py
> >       0.7887
> >
> >       D:\rft\vsl\dlr\bin>"C:\Program Files (x86)\IronPython 2.7\ipy.exe"
> > blah.py
> >       0.7633
> >
> >       D:\rft\vsl\dlr\bin>"C:\Program Files (x86)\IronPython 2.7\ipy.exe"
> > blah.py
> >       0.7683
> >
> > Dave
> >
> >
> > -----Original Message-----
> > From: users-bounces at lists.ironpython.com [mailto:users-
> > bounces at lists.ironpython.com] On Behalf Of Jeff Hardy
> > Sent: Tuesday, August 03, 2010 8:41 AM
> > To: Discussion of IronPython
> > Subject: Re: [IronPython] Exception Performance
> >
> > Hi Cory,
> >
> > On Mon, Aug 2, 2010 at 12:41 PM, Cory Brostowicz <
> cory.brostowicz at gmail.com>
> > wrote:
> > > Hello,
> > > I noticed the performance in one of my python scripts has really bad
> > > performance, so I started profiling different sections of the script
> > > to find out  where the issue is.  It turns out, the exception handle
> > > seems to add the biggest chunk of time.
> >
> > IronPython 2.6 and earlier rely on the .NET exception mechanism.
> > .NET's exception handling is extremely slow, whereas CPython has an
> extremely
> > fast exception handling system. I don't know the details of why each is
> the
> > way it is, though - engineering tradeoffs, I guess.
> >
> > IronPython 2.7 will have a 'lightweight' exception mechanism that should
> be
> > closer to the performance of CPython.
> >
> > > I've fairly new to the Python language, so if there is a better way to
> > > do what I'm doing, then please let me know.
> >
> > Unfortunately, I think that's pretty much idiomatic Python, which often
> relies
> > on it's very fast exception handling. In .NET you use the
> > Try* methods instead, which don't throw exceptions.
> >
> > If you don't need CPython compatibility, you could use
> System.Double.TryParse
> > (http://msdn.microsoft.com/en-us/library/994c0zb1.aspx), but I don't
> know how
> > to use out parameters from IronPython off the top of my head.
> >
> > On an unrelated note, you can write your print statement as:
> >
> >     print "Total: %s RateGet: %s RateSets: %s Exception Handle: %s
> > Rate: %s" % (t.Elapsed.TotalMilliseconds, rateGet, rateSet,
> > e.Elapsed.TotalMilliseconds, Rate)
> >
> > - Jeff
> > _______________________________________________
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> >
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