In the case that affects me the code isn't global. The class looks like this:
class EseDBCursor(object):
...
def __getitem__(self, key):
with _EseTransaction(self._sesid):
self._seekForKey(key)
return self._retrieveCurrentRecordValue()
def _makeKey(self, key):
"""Construct a key for the given value."""
Api.MakeKey(self._sesid, self._tableid, str(key), Encoding.Unicode,
MakeKeyGrbit.NewKey)
def _seekForKey(self, key):
"""Seek for the specified key. A KeyError exception is raised if the key
isn't found."""
self._makeKey(key)
if not Api.TrySeek(self._sesid, self._tableid, SeekGrbit.SeekEQ):
raise KeyError('key \'%s\' was not found' % key)
I tried moving the call to Api.MakeKey into _seekForKey but that didn't improve
things. It is definitely the call to Api.MakeKey that is slowing things down --
removing that one call speeds things up. The code that tests the performance
looks like this:
def insertRetrieveTest():
...
timer = Stopwatch.StartNew()
for i in xrange(n):
data = db[k]
timer.Stop()
...
# Basic test first
insertRetrieveTest()
________________________________
From: [email protected] [[email protected]]
on behalf of Dino Viehland [[email protected]]
Sent: Tuesday, April 20, 2010 12:51 PM
To: Discussion of IronPython
Subject: Re: [IronPython]Bad performance calling .NET method
Is the perf problem only there when the code is global? In general we don’t
try to optimize code which occurs at the top-level of a script – we assume the
most significant work will occur inside of function definitions. In this case
the update to “i” through each loop iteration needs to update a global value in
a dictionary rather than updating a local on the stack each time which is going
to be much more expensive. Also the reads from the globals instead of
parameters will be much more expensive as well. And while I doubt this is much
of the perf problem you’re also accessing the Unicode property on encoding each
time through in the global case. There’s also the chance depending on what
version of IronPython you’re running on that we’re staying in the interpreter.
I think on 2.6.1 we should compile the global loop eventually but it’ll still
be slower than the compiled function.
Is there a reason the top-level code needs to be efficient?
From: [email protected]
[mailto:[email protected]] On Behalf Of Laurion Burchall
Sent: Tuesday, April 20, 2010 11:57 AM
To: Discussion of IronPython
Subject: Re: [IronPython] Bad performance calling .NET method
You were right about the structs. By creating a method with the same type of
signature (struct, struct, string, Encoding, enumeration). I got the same
slowdown in a trivial DLL. This is with the .NET 2.0 version of IP:
** First, the C# code:
namespace IronPythonInteropPerf
{
using System.Text;
public struct Struct1
{
internal int i;
}
public struct Struct2
{
internal int i;
}
public enum Enumeration
{
Foo,
}
public static class Interop
{
public static void A(Struct1 a, Struct2 b, string x, Encoding encoding,
Enumeration e)
{
}
}
}
** Now the IronPython test:
import System
import System.Diagnostics
import System.Text
from System.Diagnostics import Stopwatch
from System.Text import Encoding
import clr
clr.AddReferenceByPartialName('IronPythonInteropPerf')
from IronPythonInteropPerf import *
N = 1000000
a = Struct1()
b = Struct2()
c = 'hello'
d = Enumeration.Foo
stopwatch = Stopwatch.StartNew()
for i in xrange(N):
Interop.A(a, b, c, Encoding.Unicode, d)
stopwatch.Stop()
print ' A: %s' % stopwatch.Elapsed
def foo(a1, a2, a3, a4, a5):
stopwatch = Stopwatch.StartNew()
for j in xrange(N):
Interop.A(a1, a2, a3, a4, a5)
stopwatch.Stop()
print 'foo.A: %s' % stopwatch.Elapsed
foo(a, b, c, Encoding.Unicode, d)
** Note that I am calling Interop.A twice. This gives very different results --
the call from inside of function foo() is fast (11M calls/second) but the call
from the script is slow (50K calls/second):
A: 00:00:18.6063353
foo.A: 00:00:00.0894888
There isn't a caching effect at work either -- foo() is faster if I call it
before the other code.
________________________________
From: [email protected] [[email protected]]
on behalf of Dino Viehland [[email protected]]
Sent: Tuesday, April 20, 2010 11:34 AM
To: Discussion of IronPython
Subject: Re: [IronPython]Bad performance calling .NET method
I assume something is going horribly wrong with our type checks. Can you
attach the repro? Or at least are these just classes, or are any structs, or
maybe weird classes like delegates?
And is this on .NET 2.0 or .NET 4.0?
From: [email protected]
[mailto:[email protected]] On Behalf Of Laurion Burchall
Sent: Tuesday, April 20, 2010 2:11 AM
To: Discussion of IronPython
Subject: [IronPython] Bad performance calling .NET method
I am getting terrible performance invoking a C# method from IP. I have a static
class called Api with this method:
public static void MakeKey(JET_SESID sesid, JET_TABLEID tableid, string data,
Encoding encoding, MakeKeyGrbit grbit)
When I call it directly from C# I get about 3M calls/second. In IronPython I
get only 50,000 calls/second -- a 60X slowdown!
The method is overloaded. When I call these overloads I get good performance (~
1M calls/second):
public static void MakeKey(JET_SESID sesid, JET_TABLEID tableid, int data,
MakeKeyGrbit grbit)
public static void MakeKey(JET_SESID sesid, JET_TABLEID tableid, float data,
MakeKeyGrbit grbit)
public static void MakeKey(JET_SESID sesid, JET_TABLEID tableid, byte[] data,
MakeKeyGrbit grbit)
(for the last overload I passed in the string turned into a byte array with
Encoding.GetBytes())
Things I have tried that didn't help:
- Changing the name of the method so it was unique.
- Calling the method using Api.MakeKey.Overloads[...]
- Calling other methods I have that take string arguments. They were fast.
When I profile the code the time shows up in mscorwks.dll (56%) and
mscorlib.ni.dll (17%). IronPython is only 8% and my code is 6%.
Can anyone help me work out what is going wrong? I have a short, turn-key repro
of this. MakeKey is a very commonly used method so having it be so slow is
crippling.
thanks,
--Laurion
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