Installation

For Racket with Planet2

% raco pkg install gcstats

For Racket 5.3.1

% git clone git://github.com/samth/gcstats.git
% raco link gcstats
% raco setup gcstats

Running

% racket -l gcstats normal-racket-arguments

For example:

% racket -l gcstats -t "foo.rkt"

or

% racket -l gcstats -l drracket

Example Output

  2,715,625,408 bytes allocated in the heap
  2,687,494,428 bytes collected by GC
     73,728,640 bytes max heap size
     66,748,764 bytes max slop
     85,884,928 bytes peak total memory use

Generation 0:     147 collections,    1,120ms, 1,157.53ms elapsed
Generation 1:       6 collections,      596ms,   605.63ms elapsed

INIT  time       260 ms
MUT   time     8,996 ms (  9,038.51 ms elapsed)
GC    time     1,716 ms (  1,763.16 ms elapsed)
TOTAL time    10,972 ms ( 11,061.67 ms elapsed)

%GC time       16.02%   ( 16.32% elapsed)

Alloc rate     301,870,321 bytes per MUT second

Line-by-line explanation

  2,715,625,408 bytes allocated in the heap

How many bytes, total, were allocated by the program

  2,687,494,428 bytes collected by GC

How many bytes, total, were collected during the run of the program

     73,728,640 bytes max heap size

The largest heap size observed at any GC

     66,748,764 bytes max slop

The largest difference between the memory allocated and the memory the GC has servered.

     85,884,928 bytes peak total memory use

The largest total memory use, including GC overhead.

Generation 0:     147 collections,    1,120ms, 1,157.53ms elapsed

How many nursery collections there were, and how long they took, in both process and elapsed time.

Generation 1:       6 collections,      596ms,   605.63ms elapsed

How many major collections there were, and how long they took, in both process and elapsed time.

INIT  time       260 ms

Time spent in the process prior to the logging happening. This is primarily Racket startup time, and code loading time.

MUT   time     8,996 ms (  9,038.51 ms elapsed)

How much time the "mutator", i.e. your program, was running.

GC    time     1,716 ms (  1,763.16 ms elapsed)

How much time the GC took.

TOTAL time    10,972 ms ( 11,061.67 ms elapsed)

The total time from the initial invocation.

%GC time       16.02%   ( 16.32% elapsed)

What percentage of the time (after initialization) was spent in GC.

Alloc rate     301,870,321 bytes per MUT second

The average rate of allocation, not counting GC time.

Output formatting borrowed from GHC