[Ubuntu] Child process cpu_percent() returns 0 about psutil HOT 3 CLOSED

This part:

for child in process.children(recursive=True):
    cpu_usage += child.cpu_percent(interval=None)

...creates a set of brand new Process instances, upon which you immediately call cpu_percent(). They have no knowledge of what happened before, nor they have a big enough time window to calculate a meaningful percent value, hence they return 0.
From the doc:

the first time this cpu_percent() is called with interval = 0.0 or None it will return a meaningless 0.0 value which you are supposed to ignore

from psutil.

I was assuming there is a state stored outside the psutil.Process instance, since the pcputimes.user value is consistent with the actual child that exists before its psutil twin instantiation.
And I could argue the documentation is confusing, because child.cpu_percent() is being called a first time (so as to ignore its meaningless 0.0 value), according to the PID, but not according to the psutil instance.

from psutil.

And I could argue the documentation is confusing, because child.cpu_percent() is being called a first time (so as to ignore its meaningless 0.0 value), according to the PID, but not according to the psutil instance.

I read it twice but I don't understand what you mean here. If you have suggestions on how to reword the doc please go for it.

from psutil.