This library provides predicates to obtain information about resource
usage by your program. The predicates of this library are for human use
at the toplevel: information is printed. All predicates obtain
their information using public low-level primitives. These primitives
can be use to obtain selective statistics during execution.
- [det]statistics
- Print information about resource usage using print_message/2.
- See also
- All statistics printed are obtained through statistics/2.
- [det]statistics(-Stats:dict)
- Stats is a dict representing the same information as
statistics/0.
This convience function is primarily intended to pass statistical
information to e.g., a web client. Time critical code that wishes to
collect statistics typically only need a small subset and should use statistics/2
to obtain exactly the data they need.
- [nondet]thread_statistics(?Thread,
-Stats:dict)
- Obtain statistical information about a single thread. Fails silently of
the Thread is no longer alive.
| Stats | is a dict containing status, time and
stack-size information about Thread. |
- [nondet]time(:Goal)
- Execute Goal, reporting statistics to the user. If Goal
succeeds non-deterministically, retrying reports the statistics for
providing the next answer.
Note that is no portable way to get thread-specific CPU time.
SWI-Prolog has implementations for Linux, Windows and MacOS. The
automatic detection may work on some other operating systems.
- See also
- - statistics/2
for obtaining statistics in your program and understanding the reported
values.
- call_time/2, call_time/3
to obtain the timing in a dict.
- bug
- Inference statistics are often a few off.
- call_time(:Goal,
-Time:dict)
- call_time(:Goal,
-Time:dict, -Result)
- Call Goal as call/1,
unifying Time with a dict that provides information on the
resource usage. If Goal succeeds with a choice point,
backtracking reports the time used to find the next answer,
failure or exception. If Goal succeeds deterministically no
choice point is left open. Currently Time contains the keys
below. Future versions may provide additional keys.
- wall:Seconds
- cpu:Seconds
- inferences:Count
call_time/2 is
defined as below. Note that for call_time/2
the time is only available if Goal succeeds.
call_time(Goal, Time) :-
call_time(Goal, Time, Result),
call(Result).
| Result | is one of true, false
or throw(E), depending on whether or not the goal succeeded
or raised an exception. Note that
Result may be called using call/1
to propagate the failure or exception. |