module Gc:Memory management control and statistics; finalised values.sig..end
module Stat:sig..end
typestat =Stat.t
stat record.
The total amount of memory allocated by the program since it was started
is (in words) minor_words + major_words - promoted_words. Multiply by
the word size (4 on a 32-bit machine, 8 on a 64-bit machine) to get
the number of bytes.
module Control:sig..end
typecontrol =Control.t
control record.
Note that these parameters can also be initialised
by setting the OCAMLRUNPARAM environment variable.
See the documentation of ocamlrun.val stat : unit -> statstat record. This function examines every heap block to get the
statistics.val quick_stat : unit -> statstat except that live_words, live_blocks, free_words,
free_blocks, largest_free, and fragments are set to 0. This
function is much faster than stat because it does not need to go
through the heap.val counters : unit -> float * float * float(minor_words, promoted_words, major_words). This function
is as fast at quick_stat.val get : unit -> controlcontrol record.val set : control -> unitset r changes the GC parameters according to the control record r.
The normal usage is:
Gc.set { (Gc.get()) with Gc.Control.verbose = 0x00d }val minor : unit -> unitval major_slice : int -> intval major : unit -> unitval full_major : unit -> unitval compact : unit -> unitval print_stat : Pervasives.out_channel -> unitval allocated_bytes : unit -> floatfloat to avoid overflow problems
with int on 32-bit machines.val finalise : ('a -> unit) -> 'a -> unitfinalise f v registers f as a finalisation function for v.
v must be heap-allocated. f will be called with v as
argument at some point between the first time v becomes unreachable
and the time v is collected by the GC. Several functions can
be registered for the same value, or even several instances of the
same function. Each instance will be called once (or never,
if the program terminates before v becomes unreachable).
The GC will call the finalisation functions in the order of
deallocation. When several values become unreachable at the
same time (i.e. during the same GC cycle), the finalisation
functions will be called in the reverse order of the corresponding
calls to finalise. If finalise is called in the same order
as the values are allocated, that means each value is finalised
before the values it depends upon. Of course, this becomes
false if additional dependencies are introduced by assignments.
Anything reachable from the closure of finalisation functions is considered reachable, so the following code will not work as expected:
let v = ... in Gc.finalise (fun x -> ...) v let f = fun x -> ... ;; let v = ... in Gc.finalise f v f function can use all features of O'Caml, including
assignments that make the value reachable again. It can also
loop forever (in this case, the other
finalisation functions will be called during the execution of f).
It can call finalise on v or other values to register other
functions or even itself. It can raise an exception; in this case
the exception will interrupt whatever the program was doing when
the function was called.
finalise will raise Invalid_argument if v is not
heap-allocated. Some examples of values that are not
heap-allocated are integers, constant constructors, booleans,
the empty array, the empty list, the unit value. The exact list
of what is heap-allocated or not is implementation-dependent.
Some constant values can be heap-allocated but never deallocated
during the lifetime of the program, for example a list of integer
constants; this is also implementation-dependent.
You should also be aware that compiler optimisations may duplicate
some immutable values, for example floating-point numbers when
stored into arrays, so they can be finalised and collected while
another copy is still in use by the program.
The results of calling String.make, String.create,
Array.make, and Pervasives.ref are guaranteed to be
heap-allocated and non-constant except when the length argument is 0.
val finalise_release : unit -> unitfinalise_release to tell the
GC that it can launch the next finalisation function without waiting
for the current one to return.type alarm
val create_alarm : (unit -> unit) -> alarmcreate_alarm f will arrange for f to be called at the end of each
major GC cycle, starting with the current cycle or the next one.
A value of type alarm is returned that you can
use to call delete_alarm.val delete_alarm : alarm -> unitdelete_alarm a will stop the calls to the function associated
to a. Calling delete_alarm a again has no effect.val tune : ?logger:(string -> unit) ->
?minor_heap_size:int ->
?major_heap_increment:int ->
?space_overhead:int ->
?verbose:int ->
?max_overhead:int ->
?stack_limit:int -> ?allocation_policy:int -> unit -> unit