STINNER Victor added the comment:
Hi,
Serhiy Storchaka: "The performance of print() is not critical. It usually
involves slow formatting and IO."
Oh, please, I want a print() using METH_FASTCALL! Not for the performance, but
just to help me in my development!
To identify code not using FASTCALL yet, I'm putting a breakpoint on
_PyStack_AsTuple() and _PyStack_AsDict(). It's common to stop on print() when
testing the performance benchmark suite.
FYI currnently, I'm adding the following Python code to python-gdb.py:
---
class MyBreakpoint (gdb.Breakpoint):
def stop(self):
# frame of the caller
frame = gdb.selected_frame()
frame = frame.older()
name = frame.name()
if name == '_PyCFunction_FastCallKeywords':
pass
else:
# callable->ob_type
obj = frame.read_var('callable')
obj = obj.referenced_value()['ob_type']
obj2 = gdb.lookup_global_symbol('PyType_Type').value()
if obj == obj2.address:
return False
print("don't skip", obj, obj2.address)
gdb.execute("up")
return True
MyBreakpoint("_PyStack_AsTuple")
MyBreakpoint("_PyStack_AsDict")
---
These macros make gdb 40x slower :-/
The code is used to skip type_call(): this function is known to not use
FASTCALL yet. I plan to add tp_fastnew and tp_fastinit to optimize type_call(),
but it's already hard enough to implement tp_fastcall, so I will do it later.
> _PyArg_ParseStackAndKeywords() is a part of unstable, fast-evolved API. I
> would beware of using it in common code.
Ah. I have a different opinion on that. Since _PyArg_ParseStackAndKeywords()
and print() are part of the Python core, we have free to use private
fast-moving APIs.
By the way, _PyArg_ParseStackAndKeywords() already uses the new efficient
_PyArg_Parser object. Do you plan other enhancements?
INADA Naoki: "I see. AC should support this."
Right, but IMHO it can be done later.
I tried to contribute to AC but the code is super complex. I understood that AC
is not complex, but Python is complex :-D AC is full of corner cases. It's a
very long list of special cases :-)
----------
status: pending -> open
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Python tracker <[email protected]>
<http://bugs.python.org/issue29296>
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