some improvements to GC stat printing (JuliaLang#44098)

- line up `elapsed time`
- print most numbers unconditionally
- print minor/full collections instead of all/full collections
- count `free` calls for arrays, since we count `malloc`s for them

base/timing.jl

@@ -40,7 +40,7 @@ function GC_Diff(new::GC_Num, old::GC_Num)
  # logic from `src/gc.c:jl_gc_total_bytes`
  old_allocd = gc_total_bytes(old)
  new_allocd = gc_total_bytes(new)
- return GC_Diff(new_allocd - old_allocd,
+ return GC_Diff(new_allocd  - old_allocd,
  new.malloc - old.malloc,
  new.realloc - old.realloc,
  new.poolalloc - old.poolalloc,
@@ -98,14 +98,13 @@ function prettyprint_getunits(value, numunits, factor)
  return number, unit
 end
 
-function padded_nonzero_print(value, str)
- if value != 0
- blanks = " "[1:(18 - length(str))]
+function padded_nonzero_print(value, str, always_print = true)
+ if always_print || value != 0
+ blanks = " "[1:(19 - length(str))]
  println(str, ":", blanks, value)
  end
 end
 
-
 function format_bytes(bytes) # also used by InteractiveUtils
  bytes, mb = prettyprint_getunits(bytes, length(_mem_units), Int64(1024))
  if mb == 1
@@ -152,15 +151,17 @@ end
 function timev_print(elapsedtime, diff::GC_Diff, compile_time, _lpad)
  allocs = gc_alloc_count(diff)
  time_print(elapsedtime, diff.allocd, diff.total_time, allocs, compile_time, true, _lpad)
- print("elapsed time (ns): $elapsedtime\n")
+ padded_nonzero_print(elapsedtime, "elapsed time (ns)")
  padded_nonzero_print(diff.total_time, "gc time (ns)")
  padded_nonzero_print(diff.allocd, "bytes allocated")
  padded_nonzero_print(diff.poolalloc, "pool allocs")
  padded_nonzero_print(diff.bigalloc, "non-pool GC allocs")
- padded_nonzero_print(diff.malloc, "malloc() calls")
- padded_nonzero_print(diff.realloc, "realloc() calls")
- padded_nonzero_print(diff.freecall, "free() calls")
- padded_nonzero_print(diff.pause, "GC pauses")
+ padded_nonzero_print(diff.malloc, "malloc() calls", false)
+ padded_nonzero_print(diff.realloc, "realloc() calls", false)
+ # always print number of frees if there are mallocs
+ padded_nonzero_print(diff.freecall, "free() calls", diff.malloc > 0)
+ minor_collects = diff.pause - diff.full_sweep
+ padded_nonzero_print(minor_collects, "minor collections")
  padded_nonzero_print(diff.full_sweep, "full collections")
 end
 

src/gc.c

@@ -1134,6 +1134,7 @@ static void jl_gc_free_array(jl_array_t *a) JL_NOTSAFEPOINT
  else
  free(d);
  gc_num.freed += jl_array_nbytes(a);
+ gc_num.freecall++;
  }
 }