package core_kernel

  1. Overview
  2. Docs
package core_kernel
Legend:
Library
Module
Module type
Parameter
Class
Class type

This is a wrapper around INRIA's standard Gc module. Provides memory management control and statistics, and finalized values.

module Stat : sig ... end
type stat = Stat.t

The memory management counters are returned in a 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
type control = Control.t

The GC parameters are given as a control record. Note that these parameters can also be initialised by setting the OCAMLRUNPARAM environment variable. See the documentation of ocamlrun.

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.

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:Base.Int.t -> ?window_size:Base.Int.t -> Base.Unit.t -> Base.Unit.t

Adjust the specified GC parameters.

module Allocation_policy : sig ... end

The policy used for allocating in the heap.

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 Expert : sig ... end

The Expert module contains functions that novice users should not use, due to their complexity.

OCaml

Innovation. Community. Security.

GitHub Discord Twitter Peertube RSS
About
Changelog Releases Industrial Users Academic Users Why OCaml
Ecosystem
Packages Community Events OCaml Planet Jobs
Resources
Install OCaml Get Started Platform Tools Language Manual Standard Library API Books Exercises Papers OCaml Playground Logo
Policies
Carbon Footprint Governance Privacy Code of Conduct