Statistics

The user can get statistics about memory consumptions by using statistics/0 or statistics/2.

• statistics This predicate displays the number of bytes allocated to each data area and the number of bytes already in use. The output looks like:

  
  Control stack + Heap: 4000000 bytes
  Control stack in use: 32 bytes
  Heap stack in use:    200 bytes
  
  Program area:         4000000 bytes
  Program area in use:  482984 bytes
  
  Trail stack:          2000000 bytes
  Trail stack in use:   92 bytes
  

• statistics(?Key,?Value) The statistics concerning Key are Value. This predicate gives multiple solutions on backtracking. The following shows the output the system displays after receiving the query statistics(Key,Value).

  
  | ?- statistics(Key,Value).
  
  Key = runtime
  Value = [633,633]?;
  
  Key = program
  Value = [483064,3516936]?;
  
  Key = heap
  Value = [364,3999604]?;
  
  Key = control
  Value = [32,3999604]?;
  
  Key = trail
  Value = [108,1999892]?;
  no
  

  The values for all keys are lists of two elements. For runtime, the first element denotes the amount of time in milliseconds elapsed since the start of Prolog and the second element denotes the amount of time elapsed since the previous call to statistics/2 was executed. For all other keys, the first element denotes the size of memory in use and the second element denotes the size of memory still available in the corresponding data area.