Issue 14453: profile.Profile.calibrate can produce incorrect numbers in some circumstances (original) (raw)

profile.Profile.calibrate can only produces a bias for the default timer. If you've specified a different timer, it will not be used when calibrating.

Additionally, setting profile.Profile.bias will affect the computed bias. It will produce a bias that must be added to profile.Profile.bias and cannot be used independently, which is surprising.

The fix is to change p = Profile() to p = Profile(timer=self.timer, bias=0) in _calibrate_inner().

The attached patch makes that change and additionally removes some code that temporarily resets self.bias in calibrate(), as it had no effect. Perhaps Profile.bias was meant instead. At any rate, _calibrate_inner() no longer needs to exist, but is left for backwards compatibility.

This will demonstrate the problem with calibrating after setting profile.Profile.bias:

import profile profile.Profile.bias = profile.Profile().calibrate(100000); print '%+.9f' % profile.Profile.bias profile.Profile.bias = profile.Profile().calibrate(100000); print '%+.9f' % profile.Profile.bias