Python 3.3 has 3 functions to get time:

• time.clock()
• time.steady()
• time.time()

Antoine Pitrou suggested to deprecated time.clock() in msg120149 (issue bpo-10278).

"The problem is time.clock(), since it does two wildly different things
depending on the OS. I would suggest to deprecate time.clock() at the same time as we add time.wallclock(). For the Unix-specific definition of time.clock(), there is already os.times() (which gives even richer information)."

(time.wallclock was the old name of time.steady)

STINNER Victor wrote:

New submission from STINNER Victor <victor.stinner@gmail.com>:

Python 3.3 has 3 functions to get time:

• time.clock()
• time.steady()
• time.time()

Antoine Pitrou suggested to deprecated time.clock() in msg120149 (issue bpo-10278).

"The problem is time.clock(), since it does two wildly different things
depending on the OS. I would suggest to deprecate time.clock() at the same time as we add time.wallclock(). For the Unix-specific definition of time.clock(), there is already os.times() (which gives even richer information)."

(time.wallclock was the old name of time.steady)

Strong -1 on this idea.

time.clock() has been in use for ages in many many scripts. We don't
want to carelessly break all those.

time.clock() has been in use for ages in many many scripts.
We don't want to carelessly break all those.

I don't want to remove the function, just mark it as deprecated to
avoid confusion. It will only be removed from the next major Python.

STINNER Victor wrote:

STINNER Victor <victor.stinner@gmail.com> added the comment:

> time.clock() has been in use for ages in many many scripts.
> We don't want to carelessly break all those.

I don't want to remove the function, just mark it as deprecated to
avoid confusion. It will only be removed from the next major Python.

Why ? There's no other single function providing the same functionality,
so it's not even a candidate for deprecation.

Similar functionality is available via several different functions,
but that's true for a lot functions in th stdlib.

There's no other single function providing the same functionality

time.clock() is not portable: it is a different clock depending on the OS. To write portable code, you have to use the right function:

• time.time()
• time.steady()
• os.times(), resource.getrusage()

On Windows, time.clock() should be replaced by time.steady(). On UNIX, time.clock() can be replaced with "usage=os.times(); usage[0]+usage[1]" for example.

Which kind of use case is not covered by these functions?

STINNER Victor wrote:

STINNER Victor <victor.stinner@gmail.com> added the comment:

> There's no other single function providing the same functionality

time.clock() is not portable: it is a different clock depending on the OS. To write portable code, you have to use the right function:

• time.time()
• time.steady()
• os.times(), resource.getrusage()

time.clock() does exactly what the docs say: you get access to
a CPU timer. It's normal that CPU timers work differently on
different OSes.

On Windows, time.clock() should be replaced by time.steady().

What for ? time.clock() uses the same timer as time.steady() on Windows,
AFAICT, so all you change is the name of the function.

On UNIX, time.clock() can be replaced with "usage=os.times(); usage[0]+usage[1]" for example.

And what's the advantage of that over using time.clock() directly ?

I misunderstood the time.clock() function. It counts the CPU time while the process is active, whereas a monotonic clock counts elapsed time even during a sleep. time.clock() and time.monotonic() are different clocks for different purposes.

I wrote the PEP-418 which contains a list of all available OS clocks. It lists monotonic clocks, but also "process time" and "thread time" clocks. And it has a "Deferred API: time.perf_counter()" section.

Something can be done to provide portable functions to get the user and system times. See for example Tools/pybench/systimes.py written by Marc-Andre Lemburg.

Python 3.3 gives access to clock_gettime(CLOCK_PROCESS_CPUTIME_ID) and clock_gettime(CLOCK_THREAD_CPUTIME_ID).

Something can be done to provide portable functions to get
the user and system times.

Lib/profile.py tests also various functions to choose the best one in Profile constructor.

New changeset 314c3faea2fb by Victor Stinner in branch 'default':
Close bpo-14309: Deprecate time.clock()
http://hg.python.org/cpython/rev/314c3faea2fb

The PEP-418 has been accepted: read it to understand why time.clock() is now deprecated.