We remove the Expert
module, which has functions that are superseded by Async-friendly functions below.
include module type of Core_kernel.Gc with module Expert := Core_kernel.Gc.Expert
module Stat : sig ... end
type stat = Stat.t
module Control : sig ... end
type control = Control.t
val stat : Base.Unit.t -> stat
Return the current values of the memory management counters in a stat
record. This function examines every heap block to get the statistics.
val quick_stat : Base.Unit.t -> stat
Same as stat
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 : Base.Unit.t -> Base.Float.t * Base.Float.t * Base.Float.t
Return (minor_words, promoted_words, major_words)
. This function is as fast at quick_stat
.
val minor_words : Base.Unit.t -> Base.Int.t
The following functions return the same as (Gc.quick_stat ()).Stat.f
, avoiding any allocation (of the stat
record or a float). On 32-bit machines the int
may overflow.
Note that minor_words
does not allocate, but we do not annotate it as noalloc
because we want the compiler to save the value of the allocation pointer register (%r15 on x86-64) to the global variable caml_young_ptr
before the C stub tries to read its value.
val major_words : Base.Unit.t -> Base.Int.t
val promoted_words : Base.Unit.t -> Base.Int.t
val minor_collections : Base.Unit.t -> Base.Int.t
val major_collections : Base.Unit.t -> Base.Int.t
val heap_words : Base.Unit.t -> Base.Int.t
val heap_chunks : Base.Unit.t -> Base.Int.t
val compactions : Base.Unit.t -> Base.Int.t
val top_heap_words : Base.Unit.t -> Base.Int.t
val major_plus_minor_words : Base.Unit.t -> Base.Int.t
This function returns major_words () + minor_words ()
. It exists purely for speed (one call into C rather than two). Like major_words
and minor_words
, major_plus_minor_words
avoids allocating a stat
record or a float, and may overflow on 32-bit machines.
This function is not marked [@@noalloc]
to ensure that the allocation pointer is up-to-date when the minor-heap measurement is made.
val get : Base.Unit.t -> control
Return the current values of the GC parameters in a control
record.
val set : control -> Base.Unit.t
set 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 : Base.Unit.t -> Base.Unit.t
Trigger a minor collection.
val major_slice : Base.Int.t -> Base.Int.t
Do a minor collection and a slice of major collection. The argument is the size of the slice, 0 to use the automatically-computed slice size. In all cases, the result is the computed slice size.
val major : Base.Unit.t -> Base.Unit.t
Do a minor collection and finish the current major collection cycle.
val full_major : Base.Unit.t -> Base.Unit.t
Do a minor collection, finish the current major collection cycle, and perform a complete new cycle. This will collect all currently unreachable blocks.
val compact : Base.Unit.t -> Base.Unit.t
Perform a full major collection and compact the heap. Note that heap compaction is a lengthy operation.
val print_stat : Stdlib.out_channel -> Base.Unit.t
Print the current values of the memory management counters (in human-readable form) into the channel argument.
val allocated_bytes : Base.Unit.t -> Base.Float.t
Return the total number of bytes allocated since the program was started. It is returned as a float
to avoid overflow problems with int
on 32-bit machines.
val keep_alive : _ -> Base.Unit.t
keep_alive a
ensures that a
is live at the point where keep_alive a
is called. It is like ignore a
, except that the compiler won't be able to simplify it and potentially collect a
too soon.
module Allocation_policy : sig ... end
The policy used for allocating in the heap.
val tune : ?logger:(Base.String.t -> Base.Unit.t) -> ?minor_heap_size:Base.Int.t -> ?major_heap_increment:Base.Int.t -> ?space_overhead:Base.Int.t -> ?verbose:Base.Int.t -> ?max_overhead:Base.Int.t -> ?stack_limit:Base.Int.t -> ?allocation_policy:Allocation_policy.t -> ?window_size:Base.Int.t -> ?custom_major_ratio:Base.Int.t -> ?custom_minor_ratio:Base.Int.t -> ?custom_minor_max_size:Base.Int.t -> Base.Unit.t -> Base.Unit.t
Adjust the specified GC parameters.
val disable_compaction : ?logger:(Base.String.t -> Base.Unit.t) -> allocation_policy:[ `Don't_change | `Set_to of Allocation_policy.t ] -> Base.Unit.t -> Base.Unit.t
module Stable : sig ... end
val add_finalizer : 'a Core_kernel.Heap_block.t -> ('a Core_kernel.Heap_block.t -> unit) -> unit
add_finalizer b f
ensures that f
runs after b
becomes unreachable. f b
will run in its own Async job. If f
raises, the unhandled exception will be raised to the monitor that called add_finalizer b f
.
The OCaml runtime only supports finalizers on heap blocks, hence add_finalizer
requires b : _ Heap_block.t
.
The runtime essentially maintains a set of finalizer pairs:
'a Heap_block.t * ('a Heap_block.t -> unit)
Each call to add_finalizer
adds a new pair to the set. It is allowed for many pairs to have the same heap block, the same function, or both. Each pair is a distinct element of the set.
After a garbage collection determines that a heap block b
is unreachable, it removes from the set of finalizers all finalizer pairs (b, f)
whose block is b
, and then and runs f b
for all such pairs. Thus, a finalizer registered with add_finalizer
will run at most once.
In a finalizer pair (b, f)
, it is a mistake for the closure of f
to reference (directly or indirectly) b
-- f
should only access b
via its argument. Referring to b
in any other way will cause b
to be kept alive forever, since f
itself is a root of garbage collection, and can itself only be collected after the pair (b, f)
is removed from the set of finalizers.
The f
function can use all features of OCaml and Async, since it runs as an ordinary Async job. f
can even make b
reachable again. It can even call add_finalizer
on b
or other values to register other finalizer functions.
add_finalizer_exn b f
is like add_finalizer
, but will raise if b
is not a heap block.
val add_finalizer_last : 'a Core_kernel.Heap_block.t -> (unit -> unit) -> unit
Same as add_finalizer
except that the function is not called until the value has become unreachable for the last time. This means that the finalization function does not receive the value as an argument. Every weak pointer and ephemeron that contained this value as key or data is unset before running the finalization function.
module Alarm : sig ... end
A GC alarm calls a user function after the end of each major GC cycle.