TimeUsed

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description

TimeUsed[]

gives the total number of seconds of CPU time used so far in the current Mathilda session.

Examples (4)

Every input below was run against the current Mathilda build and its output recorded.

Basic examples (2)

In[1]:= TimeUsed[] >= 0
Out[1]= True

In[2]:= Head[TimeUsed[]]
Out[2]= Real

Applications (2)

Always a Real

In[3]:= Head[TimeUsed[]]
Out[3]= Real

CPU seconds consumed so far this session

In[4]:= TimeUsed[] >= 0
Out[4]= True

Options & behaviour

The CPU-time value grows with the work done, so these examples report its sign and head rather than a fixed number.

Implementation notes

Algorithm. builtin_time_used returns (double)clock() / CLOCKS_PER_SEC as an EXPR_REAL: the total CPU seconds consumed so far in the current session. It reads the same processor clock that Timing brackets, so — like Timing — it does not advance during Pause or other idle waits (where no CPU is burned), and it counts CPU time summed over threads.

Data structures / limits. A single clock() call and a divide; takes no arguments (returns NULL for any other arity). ATTR_PROTECTED. Its resolution is $TimeUnit (1/CLOCKS_PER_SEC). The value is non-deterministic (it grows with work done); it is a session CPU clock, not a numeric kernel, so there is no packed/Compile[] surface.

• Protected.
• CPU time via clock(); does not advance during Pause or other idle waits.

Attributes: Protected.

References

See also: Pause

• Source: src/datetime.c
• Specification: docs/spec/builtins/time-and-date.md
• Tests: tests/test_datetime.c

Notes & additional examples

Notes

TimeUsed[] gives the total CPU seconds consumed so far in the current session, read from the same processor clock Timing brackets. Like Timing, it does not advance during Pause or other idle waits — only work that actually burns CPU moves it — and it counts CPU time summed over threads.

The value is non-deterministic (it grows with the work the session has done), so examples show its structure rather than a fixed number. For elapsed real time since the session began, including idle and Pause time, use SessionTime instead; its resolution is $TimeUnit.