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4.40 Obtaining Runtime Statistics
- statistics(+Key, -Value)
- Unify system statistics determined by Key with Value.
The possible keys are given in the table
6. This predicate supports additional keys for compatibility
reasons. These keys are described in table
7.
Native keys (times as float in seconds) agc Number of atom garbage collections performed agc_gained Number of atoms removed agc_time Time spent in atom garbage collections atoms Total number of defined atoms c_stack System (C-) stack limit. 0 if not known. cgc Number of clause garbage collections performed cgc_gained Number of clauses reclaimed cgc_time Time spent in clause garbage collections clauses Total number of clauses in the program codes Total size of (virtual) executable code in words cputime (User) CPU time since thread was started in seconds epoch Time stamp when thread was started functors Total number of defined name/arity pairs global Allocated size of the global stack in bytes globalused Number of bytes in use on the global stack globallimit Size to which the global stack is allowed to grow global_shifts Number of global stack expansions heapused Bytes of heap in use by Prolog (0 if not maintained) inferences Total number of passes via the call and redo ports since Prolog was started modules Total number of defined modules local Allocated size of the local stack in bytes local_shifts Number of local stack expansions locallimit Size to which the local stack is allowed to grow localused Number of bytes in use on the local stack table_space_used Amount of bytes in use by the thread's answer tables trail Allocated size of the trail stack in bytes trail_shifts Number of trail stack expansions traillimit Size to which the trail stack is allowed to grow trailused Number of bytes in use on the trail stack shift_time Time spent in stack-shifts stack Total memory in use for stacks in all threads predicates Total number of predicates. This includes predicates that are undefined or not yet resolved. process_epoch Time stamp when Prolog was started process_cputime (User) CPU time since Prolog was started in seconds thread_cputime MT-version: Seconds CPU time used by finished threads. Basically non-portable. Works on Linux, MacOSX, Windows and probably some more. threads MT-version: number of active threads threads_created MT-version: number of created threads engines MT-version: number of existing engines engines_created MT-version: number of created engines Compatibility keys (times in milliseconds) runtime [ CPU time, CPU time since last ] (milliseconds, excluding time spent in garbage collection) system_time [ System CPU time, System CPU time since last ] (milliseconds) real_time [ Wall time, Wall time since last ] (integer seconds. See get_time/1) walltime [ Wall time since start, Wall time since last] (milliseconds, SICStus compatibility) memory [ Total unshared data, free memory ] (Uses getrusage() if available, otherwise incomplete own statistics.) stacks [ global use, local use ] program [ heap, 0 ] global_stack [ global use, global free ] local_stack [ local use, local free ] trail [ trail use, trail free ] garbage_collection [ number of GC, bytes gained, time spent, bytes left ] The last column is a SWI-Prolog extension. It contains the sum of the memory left after each collection, which can be divided by the count to find the average working set size after GC. Use [Count, Gained, Time|_]
for compatiblity.stack_shifts [ global shifts, local shifts, time spent ] atoms [ number, memory use, 0 ] atom_garbage_collection [ number of AGC, bytes gained, time spent ] clause_garbage_collection [ number of CGC, clauses gained, time spent ] core Same as memory - statistics
- Display a table of system statistics on the stream
user_error
. - time(:Goal)
- Execute Goal just like call/1 and print time used, number of logical inferences and the average number of lips (logical inferences per second). Note that SWI-Prolog counts the actual executed number of inferences rather than the number of passes through the call and redo ports of the theoretical 4-port model. If Goal is non-deterministic, print statistics for each solution, where the reported values are relative to the previous answer.