[issue40314] python code order of magnitude faster than equivalent CPython code for simple import statement
deekay added the comment: The times are correct. It's very noticeable even without using a stopwatch. The C version actually takes 23 seconds to execute. -- ___ Python tracker <https://bugs.python.org/issue40314> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40314] python code order of magnitude faster than equivalent CPython code for simple import statement
New submission from deekay :
I'm baffled by the performance difference of the following two semantically
equivalent(?) programs.
Python:
#test.py
import time
starttime=time.time()
import tensorflow
print(f"Import took: {time.time() - starttime}")
vs C using CPython
//test.c
#include
#include
#include
int main(int argc, char *argv[])
{
Py_Initialize();
clock_t t = clock();
PyObject* pModule = PyImport_ImportModule("tensorflow");
double time_taken = ((double)clock() - t)/CLOCKS_PER_SEC;
printf("Import took: %f\n", time_taken);
return 0;
}
Now compare the two:
cl.exe /I"C:\Program Files\Python37\include" test.c
link test.obj python37.lib /LIBPATH:"C:\Program Files\Python37\libs"
.\test.exe
> 2020-04-17 13:00:51.598550: W
> tensorflow/stream_executor/platform/default/dso_loader.cc:55] Could not load
> dynamic library 'cudart64_100.dll'; dlerror: cudart64_100.dll not found
> 2020-04-17 13:00:51.606296: I
> tensorflow/stream_executor/cuda/cudart_stub.cc:29] Ignore above cudart
> dlerror if you do not have a GPU set up on your machine.
> **Import took: 23.160523891448975**
python test.py
> 2020-04-17 13:01:19.525648: W
> tensorflow/stream_executor/platform/default/dso_loader.cc:55] Could not load
> dynamic library 'cudart64_100.dll'; dlerror: cudart64_100.dll not found
> 2020-04-17 13:01:19.530726: I
> tensorflow/stream_executor/cuda/cudart_stub.cc:29] Ignore above cudart
> dlerror if you do not have a GPU set up on your machine.
> **Import took: 2.3172824382781982**
Not that it should matter much but my tensorflow version is 1.15
Why is the python VM code so much faster than the compiled CPython code?
Does the python vm add some magic that PyImport_ImportModule doesn't?
--
components: C API
messages: 366683
nosy: deekay
priority: normal
severity: normal
status: open
title: python code order of magnitude faster than equivalent CPython code for
simple import statement
versions: Python 3.7
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[issue40312] Weakref callbacks running before finalizers in GC collection
deekay added the comment: Wrong thread, wrong thread, abort! Sorry, I meant to submit this as a separate issue. I don't see a delete option. Maybe a mod can remove this please? -- ___ Python tracker <https://bugs.python.org/issue40312> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40312] Weakref callbacks running before finalizers in GC collection
deekay added the comment:
I'm baffled by the performance difference of the following two semantically
equivalent(?) programs.
Python:
#test.py
import time
starttime=time.time()
import tensorflow
print(f"Import took: {time.time() - starttime}")
C using CPython
//test.c
#include
#include
#include
int main(int argc, char *argv[])
{
Py_Initialize();
clock_t t = clock();
PyObject* pModule = PyImport_ImportModule("tensorflow");
double time_taken = ((double)clock() - t)/CLOCKS_PER_SEC;
printf("Import took: %f\n", time_taken);
return 0;
}
Now compare the two:
cl.exe /I"C:\Program Files\Python37\include" test.c
link test.obj python37.lib /LIBPATH:"C:\Program Files\Python37\libs"
.\test.exe
> 2020-04-17 13:00:51.598550: W
> tensorflow/stream_executor/platform/default/dso_loader.cc:55] Could not load
> dynamic library 'cudart64_100.dll'; dlerror: cudart64_100.dll not found
> 2020-04-17 13:00:51.606296: I
> tensorflow/stream_executor/cuda/cudart_stub.cc:29] Ignore above cudart
> dlerror if you do not have a GPU set up on your machine.
> **Import took: 23.160523891448975**
python test.py
> 2020-04-17 13:01:19.525648: W
> tensorflow/stream_executor/platform/default/dso_loader.cc:55] Could not load
> dynamic library 'cudart64_100.dll'; dlerror: cudart64_100.dll not found
> 2020-04-17 13:01:19.530726: I
> tensorflow/stream_executor/cuda/cudart_stub.cc:29] Ignore above cudart
> dlerror if you do not have a GPU set up on your machine.
> **Import took: 2.3172824382781982**
Not that it should matter much but my tensorflow version is 1.15
Why is the python VM code so much faster than the compiled CPython code?
Does the python vm add some magic that PyImport_ImportModule doesn't?
--
nosy: +deekay
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