10.10.6 Statistics Predicates

The following predicates can be used to access execution statistics.

fd_statistics(?Key, ?Value)

This allows a program to access execution statistics specific to this solver. General statistics about CPU time and memory consumption etc. is available from the built-in predicate statistics/2.

Without arguments, displays on the standard error stream a summary of the following statistics, and zeroes all counters. With arguments, for each of the possible keys Key, Value is unified with the current value of a counter, which is simultaneously zeroed. The following counters are maintained:


The number of times a constraint was resumed.


The number of times a (dis)entailment was detected by a constraint.


The number of times a domain was pruned.


The number of times a contradiction was found by a domain being wiped out, or by a global constraint signalling failure. Other causes of backtracking, such as failed Prolog tests, are not covered by this counter.


The number of propagators created.

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