Improve performance of unwrapping .NET objects passed from Python #930
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This addresses the following scenario: 1. A C# object `a` is created and filled with some data. 2. `a` is passed via Python.NET to Python. To do that Python.NET creates a wrapper object `w`, and stores reference to `a` in one of its fields. 3. Python code later passes `w` back to C#, e.g. calls `SomeCSharpMethod(w)`. 4. Python.NET has to unwrap `w`, so it reads the reference to `a` from it. Prior to this change in 4. Python.NET had to determine what kind of an object `a` is. If it is an exception, a different offset needed to be used. That check was very expensive (up to 4 calls into Python interpreter). This change replaces that check with computing offset unconditionally by subtracting a constant from the object size (which is read from the wrapper), thus avoiding calls to Python interpreter.
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Codecov Report
@@ Coverage Diff @@
## master #930 +/- ##
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- Coverage 86.66% 86.33% -0.34%
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Files 1 1
Lines 300 300
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- Hits 260 259 -1
- Misses 40 41 +1
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Sorry for the delay, cherry-picking didn't work (I assume the given commit is not in any of the branches on the main fork). |
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Hm, it shows in this fork. This is a very small change though, you can copy it manually. |
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I did (just before commenting ;)). |
lostmsu
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Mar 9, 2020
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Jun 15, 2020
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AlexCatarino
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Jun 29, 2020
…thonnet#930) This addresses the following scenario: 1. A C# object `a` is created and filled with some data. 2. `a` is passed via Python.NET to Python. To do that Python.NET creates a wrapper object `w`, and stores reference to `a` in one of its fields. 3. Python code later passes `w` back to C#, e.g. calls `SomeCSharpMethod(w)`. 4. Python.NET has to unwrap `w`, so it reads the reference to `a` from it. Prior to this change in 4. Python.NET had to determine what kind of an object `a` is. If it is an exception, a different offset needed to be used. That check was very expensive (up to 4 calls into Python interpreter). This change replaces that check with computing offset unconditionally by subtracting a constant from the object size (which is read from the wrapper), thus avoiding calls to Python interpreter. Co-authored-by: Victor Milovanov <lost@losttech.software>
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Upstreams QuantConnect#31 by @lostmsu.
Comment by the author:
This addresses the following scenario:
ais created and filled with some data.ais passed via Python.NET to Python. To do that Python.NET creates a wrapper objectw, and stores reference toain one of its fields.wback to C#, e.g. callsSomeCSharpMethod(w).w, so it reads the reference toafrom it.Prior to this change in 4. Python.NET had to determine what kind of an object
ais. If it is an exception, a different offset needed to be used. That check was very expensive (up to 4 calls into Python interpreter).This change replaces that check with computing offset unconditionally by subtracting a constant from the object size (which is read from the wrapper), thus avoiding calls to Python interpreter.