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statistics(?Keyword, -Value)

Succeeds if the statistics item Keyword has value Value.
Keyword
Atom or Variable.
Value
Prolog term.

Description

Used to retrieve various statistical information about the running ECLiPSe . To print a list of all the current values, statistics/0 can be used.

The following list details the statistic items:

shared_heap_allocated

Unit : bytes

Description : The amount of memory assigned to the code heap, i.e. the area used for storing compiled Prolog code, atoms, records, non-logical variables, descriptors, buffers etc. This area will never shrink.

shared_heap_used

Unit : bytes

Description : The amount of memory currently used for compiled Prolog code, atoms, records, non-logical variables, descriptors, buffers etc.

control_stack_allocated

Unit : bytes

Description : The amount of control stack currently allocated. The control stack is allocated in chunks, up to a maximum controlled by the -l command line option. The local and control stacks share the same memory area specified by the -l option, which thus gives the maximum combined allocated size of these two stacks.

control_stack_peak

Unit : bytes

Description : The peak allocated size of the control stack during this session. Chunks of memory can be allocated to, and deallocated from, the control stack as it grows and shrinks.

control_stack_used

Unit : bytes

Description : The amount of control stack currently in use. This stack holds information needed for backtracking.

dictionary_entries

Unit : count

Description : The number of atoms and functors that are currently known to the system. This is equal to the number of solutions that current_functor/1 would return.

dict_hash_usage

Unit : List of counts

Description : Returns a list of two numbers: the number of slots in hash table of the dictionary that are actually used, and the number of slots in the dictionary hash table.

dict_hash_collisions

Unit : list of counts

Description : Returns a list of two numbers: the length of the longest list in a hash table slot (i.e. the maximum number of dictionary entries that are hashed to the same slot), and the number of slots in the dictionary hash table.

dict_gc_number

Unit : count

Description : The number of dictionary garbage collections performed during this session.

dict_gc_time

Unit : seconds

Description : The total cputime spent by all dictionary garbage collections performed during this session.

event_time

Unit : Seconds

Description : Returns the elapsed real time (session_time) or the elapsed user time (cputime) since the start of a (parallel) ECLiPSe session depending on the value of the after_event_timer flag.

gc_area

Unit : bytes

Description : The average area processed by a garbage collection. This number should be close to the value of gc_interval. If it is much higher, gc_interval should be increased.

gc_collected

Unit : bytes

Description : The total number of bytes collected in the global stack during all the garbage collections in this session.

gc_number

Unit : count

Description : The number of global/trail stack garbage collections performed during this session.

gc_ratio

Unit : percent

Description : The average percentage of garbage found and collected in the garbage collections performed so far. If this number is low, gc_interval should be increased.

gc_time

Unit : seconds

Description : The total time spent for all garbage collections in this session.

private_heap_allocated

Unit : bytes

Description : The amount of memory assigned to the private heap. This area will never shrink.

private_heap_used

Unit : bytes

Description : The amount of memory currently used for private data.

global_stack_allocated

Unit : bytes

Description : The amount of global stack currently allocated. The global stack is allocated in chunks, up to a maximum controlled by the -g command line option. The global stack and trail share the same memory area specified by the -g option, which thus gives the maximum possible combined allocated size of these two stacks.

global_stack_peak

Unit : bytes

Description : The peak allocated size of the global stack during this session. Chunks of memory can be allocated to, and deallocated from, the global stack as it grows and shrinks.

global_stack_used

Unit : bytes

Description : The amount of global stack currently in use. The global stack holds lists and structures and is subject to garbage collection.

local_stack_allocated

Unit : bytes

Description : The amount of local stack currently allocated. The local stack is allocated in chunks, up to a maximum controlled by the -l command line option. The local and control stacks share the same memory area specified by the -l option, which thus gives the maximum combined allocated size of these two stacks.

local_stack_peak

Unit : bytes

Description : The peak allocated size of the local stack during this session. Chunks of memory can be allocated to, and deallocated from, the local stack as it grows and shrinks.

local_stack_used

Unit : bytes

Description : The amount of local stack currently in use. This stack holds Prolog variables and return addresses.

memory, core

Unit : List of bytes

Description : The second number is always zero. The first number is the total amount of memory currently allocated in the various stacks. This is provided mainly for compatibility.

program, heap

Unit : List of bytes

Description : Returns a list of two numbers for the allocated shared heap, where, along with other items, program code is stored: the number of bytes currently used, and the number of bytes currently free. It is provided mainly for compatibility.

global_stack

Unit : List of bytes

Description : Returns a list of two numbers for the allocated global stack: the number of bytes currently used, and the number of bytes currently free. It is provided mainly for compatibility.

local_stack

Unit : List of bytes

Description : Returns a list of two numbers on the current usage of the allocated local and control stacks. In the original WAM, these two stacks are combined into a single stack. This is provided for compatibility purposes only.

trail

Unit : List of bytes

Description : Returns a list of two numbers for the allocated trail: the number of bytes currently used, and the number of bytes currently free. It is provided mainly for compatibility.

garbage_collection

Unit : List of numbers

Descriptions : Returns a list that summaries garbage collections during this session: the number of times it has occurred, the number of bytes freed, and the total time spent (in seconds). This is provided mainly for compatibility purposes.

runtime

Unit : List of milliseconds

Description : Returns a list of two times: user cpu time since the start of the ECLiPSe session, user cpu time since the last call to statistics(runtime, _). As from ECLiPSe 4.2, these times exclude the time spent in garbage collection. This item is provided primarily for compatibility reasons.

session_time

Unit : Seconds

Description : Returns the real time elapsed since the start of a (parallel) ECLiPSe session. This is the only timer that can be reliably used in a parallel execution, since it accesses a central clock. All other timers are local to the worker where they are accessed.

times

Unit : List of seconds

Description : Returns a list of three times: user cpu time, system cpu time and real time elapsed since the start of the ECLiPSe session.

trail_stack_allocated

Unit : bytes

Description : The amount of trail stack currently allocated. The trail is allocated in chunks, up to a maximum controlled by the -g command line option. The global stack and trail share the same memory area specified by the -g option, which thus gives the maximum possible combined allocated size of these two stacks.

trail_stack_peak

Unit : bytes

Description : The peak allocated size of the trail stack during this session. Chunks of memory can be allocated to, and deallocated from, the trail stack as it grows and shrinks.

trail_stack_used

Unit : bytes

Description : The amount of trail stack currently in use. The trail stack records information needed for backtracking and is subject to garbage collection.

Modes and Determinism

Exceptions

(5) type error
Keyword is neither an atom nor variable.

Examples

Success:
   [eclipse]: statistics(times, [_,_,T]).
   T = 2848.64
   yes.
   [eclipse]: statistics(global_stack_used, G).
   G = 136
   yes.
Fail:
   statistics(times, [T]).
Error:
   statistics("time", T).    (Error 5)




See Also

set_flag / 2, env / 0, statistics / 0