percent(interval=None) always returns 0 regardless of interval value PYTHON
无论间隔值如何，代码始终返回0.0值。
import psutil
p = psutil.Process()
print p.cpu_percent(interval=1)
print p.cpu_percent(interval=None)
This behaviour is documented:
When interval is 0.0 or None compares process times to system CPU times elapsed since last call, returning immediately. That means the first time this is called it will return a meaningless 0.0 value which you are supposed to ignore. In this case is recommended for accuracy that this function be called a second time with at least 0.1 seconds between calls.
There is also a warning against using interval=None for a single call:
Warning: the first time this function is called with interval = 0.0 or None it will return a meaningless 0.0 value which you are supposed to ignore.
If using interval=None , make sure to call .cpu_percent compared to a prior call.
p = psutil.Process(pid=pid)
p.cpu_percent(interval=None)
for i in range(100):
usage = p.cpu_percent(interval=None)
# do other things
instead of:
for i in range(100):
p = psutil.Process(pid=pid)
p.cpu_percent(interval=None)
# do other things
从我自己的代码中可以发现：
cpu = psutil.cpu_times_percent(interval=0.4, percpu=False)
The cpu of a Process object is mutable. I have done some tests for you.
for i in range(10):
p = psutil.Process(3301)
print p.cpu_percent(interval=0.1)
result: 9.9 0.0 0.0 0.0 0.0 9.9 0.0 9.9 0.0 0.0
So if you want to get the CPU percent of a Process object, you could take the average in certain time.
test_list = []
for i in range(10):
p = psutil.Process(6601)
p_cpu = p.cpu_percent(interval=0.1)
test_list.append(p_cpu)
print float(sum(test_list))/len(test_list)
result: 1.98
