4.42 Execution profiling
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4.42.1 library(prolog_profile): Execution profiler

This module provides a simple frontend on the execution profiler with a hook to the GUI visualiser for profiling results defined in library(swi/pce_profile).

profile(:Goal)
profile(:Goal, +Options)
Run once(Goal) under the execution profiler. If the (xpce) GUI is enabled this predicate is hooked by library(swi/pce_profile) and results are presented in a gui that enables navigating the call tree and jump to predicate implementations. Without the GUI, a simple textual report is generated. Defined options are:
time(Which)
Profile cpu or wall time. The default is CPU time.
sample_rate(Rate)
Samples per second, any numeric value between 1 and 1000. Default is defined by the Prolog flag profile_sample_rate, which defaults to 200.
ports(Bool)
Specifies ports counted - true (all ports), false (call port only) or classic (all with some errors). Accomodates space/accuracy tradeoff building call tree. Default is defined by the Prolog flag profile_ports, which defaults to true.
top(N)
When generating a textual report, show the top N predicates.
cumulative(Bool)
If true (default false), show cumulative output in a textual report.
See also
show_coverage/2 from library(test_cover).
To be done
The textual input reflects only part of the information.
show_profile(+Options)
Display last collected profiling data. Options are
top(N)
When generating a textual report, show the top N predicates.
cumulative(Bool)
If true (default false), show cumulative output in a textual report.
[det]profile_data(-Data)
Gather all relevant data from profiler. This predicate may be called while profiling is active in which case it is suspended while collecting the data. Data is a dict providing the following fields:
summary:Dict
Overall statistics providing

  • samples:Count: Times the statistical profiler was called
  • ticks:Count Virtual ticks during profiling
  • accounting:Count Tick spent on accounting
  • time:Seconds Total time sampled
  • nodes:Count Nodes in the call graph.
  • sample_period: MicroSeconds Same interval timer period in micro seconds
  • ports: Ports One of true, false or classic
nodes
List of nodes. Each node provides:

  • predicate:PredicateIndicator
  • ticks_self:Count
  • ticks_siblings:Count
  • call:Count
  • redo:Count
  • exit:Count
  • callers:list_of(Relative)
  • callees:list_of(Relative)

Relative is a term of the shape below that represents a caller or callee. Future versions are likely to use a dict instead. 

node(PredicateIndicator, CycleID, Ticks, TicksSiblings,
     Calls, Redos, Exits)
[nondet]profile_procedure_data(?Pred, -Data:dict)
Collect data for Pred. If Pred is unbound data for each predicate that has profile data available is returned. Data is described in profile_data/1 as an element of the nodes key.