Various timing functions are provided as a time unit . Thus, the time module must be imported, otherwise it will be an error because the definition of
time.process_time () is present in the
time module .
Example: understand the use of process_time ().
Example: understand the use of
process_time_ns () .
process_time () is very different from
pref_counter () because
perf_counter ( ) calculates program time with
perf_counter () time and if there is any interruption but process_counter only calculates system and CPU time, during process it does not include timeout.
Advantages of process_time ():
1. process_time () provides the system and user CPU time of the current process.
2. We can calculate both float and integer values of time in seconds and nanoseconds.
3. Used whenever you need to calculate CPU time for a specific process.
If you just want to measure the elapsed wall-clock time between two points, you could use
import time start = time.time() print("hello") end = time.time() print(end - start)
This gives the execution time in seconds.
Another option since 3.3 might be to use
process_time, depending on your requirements. Before 3.3 it was recommended to use
time.clock (thanks Amber). However, it is currently deprecated:
On Unix, return the current processor time as a floating point number expressed in seconds. The precision, and in fact the very definition of the meaning of ‚Äúprocessor time‚Äù, depends on that of the C function of the same name.
On Windows, this function returns wall-clock seconds elapsed since the first call to this function, as a floating point number, based on the Win32 function
QueryPerformanceCounter(). The resolution is typically better than one microsecond.
Deprecated since version 3.3: The behaviour of this function depends on the platform: use
process_time()instead, depending on your requirements, to have a well defined behaviour.
In Python 3.3+:
from subprocess import STDOUT, check_output output = check_output(cmd, stderr=STDOUT, timeout=seconds)
output is a byte string that contains command"s merged stdout, stderr data.
CalledProcessError on non-zero exit status as specified in the question"s text unlike
shell=True because it is often used unnecessarily. You can always add it back if
cmd indeed requires it. If you add
shell=True i.e., if the child process spawns its own descendants;
check_output() can return much later than the timeout indicates, see Subprocess timeout failure.
The timeout feature is available on Python 2.x via the
subprocess32 backport of the 3.2+ subprocess module.
If you want to measure CPU time, can use
time.process_time() for Python 3.3 and above:
import time start = time.process_time() # your code here print(time.process_time() - start)
First call turns the timer on, and second call tells you how many seconds have elapsed.
There is also a function
time.clock(), but it is deprecated since Python 3.3 and will be removed in Python 3.8.
There are better profiling tools like
profile, however time.process_time() will measure the CPU time and this is what you"re are asking about.
If you want to measure wall clock time instead, use
Previously in 2.7, according to the time module docs:
On Unix, return the current processor time as a floating point number expressed in seconds. The precision, and in fact the very definition of the meaning of ‚Äúprocessor time‚Äù, depends on that of the C function of the same name, but in any case, this is the function to use for benchmarking Python or timing algorithms.
On Windows, this function returns wall-clock seconds elapsed since the first call to this function, as a floating point number, based on the Win32 function QueryPerformanceCounter(). The resolution is typically better than one microsecond.
Additionally, there is the timeit module for benchmarking code snippets.
Since time.clock() is deprecated as of Python 3.3, you will want to use
time.perf_counter() for system-wide timing, or
time.process_time() for process-wide timing, just the way you used to use
import time t = time.process_time() #do some stuff elapsed_time = time.process_time() - t
The new function
process_time will not include time elapsed during sleep.