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GC

module GC

The GC module provides an interface to Ruby's mark and sweep garbage collection mechanism-

Some of the underlying methods are also available via the ObjectSpace module.

You may obtain information about the operation of the GC through GC::Profiler.

Constants

INTERNAL_CONSTANTS
OPTS

Public Class Methods

count → Integer Show source

The number of times GC occurred-

It returns the number of times GC occurred since the process started.

static VALUE
gc_count(VALUE self)
{
    return SIZET2NUM(rb_gc_count());
}

disable → true or false Show source

Disables garbage collection, returning true if garbage collection was already disabled.

GC.disable   #=> false
GC.disable   #=> true

VALUE
rb_gc_disable(void)
{
    rb_objspace_t *objspace = &rb_objspace;
    int old = dont_gc;

    gc_rest(objspace);

    dont_gc = TRUE;
    return old ? Qtrue : Qfalse;
}

enable → true or false Show source

Enables garbage collection, returning true if garbage collection was previously disabled.

GC.disable   #=> false
GC.enable    #=> true
GC.enable    #=> false

VALUE
rb_gc_enable(void)
{
    rb_objspace_t *objspace = &rb_objspace;
    int old = dont_gc;

    dont_gc = FALSE;
    return old ? Qtrue : Qfalse;
}

latest_gc_info -> {:gc_by→:newobj} Show source

latest_gc_info(hash) → hash

latest_gc_info(:major_by) → :malloc

Returns information about the most recent garbage collection.

static VALUE
gc_latest_gc_info(int argc, VALUE *argv, VALUE self)
{
    rb_objspace_t *objspace = &rb_objspace;
    VALUE arg = Qnil;

    if (rb_scan_args(argc, argv, "01", &arg) == 1) {
        if (!SYMBOL_P(arg) && !RB_TYPE_P(arg, T_HASH)) {
            rb_raise(rb_eTypeError, "non-hash or symbol given");
        }
    }

    if (arg == Qnil) {
        arg = rb_hash_new();
    }

    return gc_info_decode(objspace, arg, 0);
}

malloc_allocated_size → Integer Show source

Returns the size of memory allocated by malloc().

Only available if ruby was built with CALC_EXACT_MALLOC_SIZE.

static VALUE
gc_malloc_allocated_size(VALUE self)
{
    return UINT2NUM(rb_objspace.malloc_params.allocated_size);
}

malloc_allocations → Integer Show source

Returns the number of malloc() allocations.

Only available if ruby was built with CALC_EXACT_MALLOC_SIZE.

static VALUE
gc_malloc_allocations(VALUE self)
{
    return UINT2NUM(rb_objspace.malloc_params.allocations);
}

start → nil Show source

start(full_mark: true, immediate_sweep: true) → nil

Initiates garbage collection, unless manually disabled.

This method is defined with keyword arguments that default to true:

def GC.start(full_mark: true, immediate_sweep: true); end

Use full_mark: false to perform a minor GC- Use immediate_sweep: false to defer sweeping (use lazy sweep)-

Note: These keyword arguments are implementation and version dependent- They are not guaranteed to be future-compatible, and may be ignored if the underlying implementation does not support them-

static VALUE
gc_start_internal(int argc, VALUE *argv, VALUE self)
{
    rb_objspace_t *objspace = &rb_objspace;
    int full_mark = TRUE, immediate_mark = TRUE, immediate_sweep = TRUE;
    VALUE opt = Qnil;
    static ID keyword_ids[3];

    rb_scan_args(argc, argv, "0:", &opt);

    if (!NIL_P(opt)) {
        VALUE kwvals[3];

        if (!keyword_ids[0]) {
            keyword_ids[0] = rb_intern("full_mark");
            keyword_ids[1] = rb_intern("immediate_mark");
            keyword_ids[2] = rb_intern("immediate_sweep");
        }

        rb_get_kwargs(opt, keyword_ids, 0, 3, kwvals);

        if (kwvals[0] != Qundef) full_mark = RTEST(kwvals[0]);
        if (kwvals[1] != Qundef) immediate_mark = RTEST(kwvals[1]);
        if (kwvals[2] != Qundef) immediate_sweep = RTEST(kwvals[2]);
    }

    garbage_collect(objspace, full_mark, immediate_mark, immediate_sweep, GPR_FLAG_METHOD);
    if (!finalizing) finalize_deferred(objspace);

    return Qnil;
}

stat → Hash Show source

stat(hash) → hash

stat(:key) → Numeric

Returns a Hash containing information about the GC-

The hash includes information about internal statistics about GC such as:

{
    :count=>0,
    :heap_allocated_pages=>24,
    :heap_sorted_length=>24,
    :heap_allocatable_pages=>0,
    :heap_available_slots=>9783,
    :heap_live_slots=>7713,
    :heap_free_slots=>2070,
    :heap_final_slots=>0,
    :heap_marked_slots=>0,
    :heap_swept_slots=>0,
    :heap_eden_pages=>24,
    :heap_tomb_pages=>0,
    :total_allocated_pages=>24,
    :total_freed_pages=>0,
    :total_allocated_objects=>7796,
    :total_freed_objects=>83,
    :malloc_increase_bytes=>2389312,
    :malloc_increase_bytes_limit=>16777216,
    :minor_gc_count=>0,
    :major_gc_count=>0,
    :remembered_wb_unprotected_objects=>0,
    :remembered_wb_unprotected_objects_limit=>0,
    :old_objects=>0,
    :old_objects_limit=>0,
    :oldmalloc_increase_bytes=>2389760,
    :oldmalloc_increase_bytes_limit=>16777216
}

The contents of the hash are implementation specific and may be changed in the future.

This method is only expected to work on C Ruby.

static VALUE
gc_stat(int argc, VALUE *argv, VALUE self)
{
    VALUE arg = Qnil;

    if (rb_scan_args(argc, argv, "01", &arg) == 1) {
        if (SYMBOL_P(arg)) {
            size_t value = gc_stat_internal(arg);
            return SIZET2NUM(value);
        }
        else if (!RB_TYPE_P(arg, T_HASH)) {
            rb_raise(rb_eTypeError, "non-hash or symbol given");
        }
    }

    if (arg == Qnil) {
        arg = rb_hash_new();
    }
    gc_stat_internal(arg);
    return arg;
}

stress → fixnum, true or false Show source

Returns current status of GC stress mode-

static VALUE
gc_stress_get(VALUE self)
{
    rb_objspace_t *objspace = &rb_objspace;
    return ruby_gc_stress_mode;
}

stress = flag → flag Show source

Updates the GC stress mode-

When stress mode is enabled, the GC is invoked at every GC opportunity: all memory and object allocations-

Enabling stress mode will degrade performance, it is only for debugging-

flag can be true, false, or a fixnum bit-ORed following flags-

0x01:: no major GC
0x02:: no immediate sweep
0x04:: full mark after malloc/calloc/realloc

static VALUE
gc_stress_set_m(VALUE self, VALUE flag)
{
    rb_objspace_t *objspace = &rb_objspace;
    rb_secure(2);
    gc_stress_set(objspace, flag);
    return flag;
}

verify_internal_consistency → nil Show source

Verify internal consistency.

This method is implementation specific. Now this method checks generational consistency if RGenGC is supported.

static VALUE
gc_verify_internal_consistency(VALUE self)
{
    rb_objspace_t *objspace = &rb_objspace;
    struct verify_internal_consistency_struct data = {0};
    struct each_obj_args eo_args;

    data.objspace = objspace;
    gc_report(5, objspace, "gc_verify_internal_consistency: start\n");

    /* check relations */

    eo_args.callback = verify_internal_consistency_i;
    eo_args.data = (void *)&data;
    objspace_each_objects((VALUE)&eo_args);

    if (data.err_count != 0) {
#if RGENGC_CHECK_MODE >= 5
        objspace->rgengc.error_count = data.err_count;
        gc_marks_check(objspace, NULL, NULL);
        allrefs_dump(objspace);
#endif
        rb_bug("gc_verify_internal_consistency: found internal inconsistency.");
    }

    /* check heap_page status */
    gc_verify_heap_pages(objspace);

    /* check counters */

    if (!is_lazy_sweeping(heap_eden) && !finalizing) {
        if (objspace_live_slots(objspace) != data.live_object_count) {
            fprintf(stderr, "heap_pages_final_slots: %d, objspace->profile.total_freed_objects: %d\n",
                    (int)heap_pages_final_slots, (int)objspace->profile.total_freed_objects);
            rb_bug("inconsistent live slot nubmer: expect %"PRIuSIZE", but %"PRIuSIZE".", objspace_live_slots(objspace), data.live_object_count);
        }
    }

#if USE_RGENGC
    if (!is_marking(objspace)) {
        if (objspace->rgengc.old_objects != data.old_object_count) {
            rb_bug("inconsistent old slot nubmer: expect %"PRIuSIZE", but %"PRIuSIZE".", objspace->rgengc.old_objects, data.old_object_count);
        }
        if (objspace->rgengc.remembered_wb_unprotected_objects != data.remembered_shady_count) {
            rb_bug("inconsistent old slot nubmer: expect %"PRIuSIZE", but %"PRIuSIZE".", objspace->rgengc.remembered_wb_unprotected_objects, data.remembered_shady_count);
        }
    }
#endif

    if (!finalizing) {
        size_t list_count = 0;

        {
            VALUE z = heap_pages_deferred_final;
            while (z) {
                list_count++;
                z = RZOMBIE(z)->next;
            }
        }

        if (heap_pages_final_slots != data.zombie_object_count ||
            heap_pages_final_slots != list_count) {

            rb_bug("inconsistent finalizing object count:\n"
                   "  expect %"PRIuSIZE"\n"
                   "  but    %"PRIuSIZE" zombies\n"
                   "  heap_pages_deferred_final list has %"PRIuSIZE" items.",
                   heap_pages_final_slots,
                   data.zombie_object_count,
                   list_count);
        }
    }

    gc_report(5, objspace, "gc_verify_internal_consistency: OK\n");

    return Qnil;
}

Public Instance Methods

garbage_collect → nil Show source

garbage_collect(full_mark: true, immediate_sweep: true) → nil

Initiates garbage collection, unless manually disabled.

This method is defined with keyword arguments that default to true:

def GC.start(full_mark: true, immediate_sweep: true); end

Use full_mark: false to perform a minor GC- Use immediate_sweep: false to defer sweeping (use lazy sweep)-

Note: These keyword arguments are implementation and version dependent- They are not guaranteed to be future-compatible, and may be ignored if the underlying implementation does not support them-

static VALUE
gc_start_internal(int argc, VALUE *argv, VALUE self)
{
    rb_objspace_t *objspace = &rb_objspace;
    int full_mark = TRUE, immediate_mark = TRUE, immediate_sweep = TRUE;
    VALUE opt = Qnil;
    static ID keyword_ids[3];

    rb_scan_args(argc, argv, "0:", &opt);

    if (!NIL_P(opt)) {
        VALUE kwvals[3];

        if (!keyword_ids[0]) {
            keyword_ids[0] = rb_intern("full_mark");
            keyword_ids[1] = rb_intern("immediate_mark");
            keyword_ids[2] = rb_intern("immediate_sweep");
        }

        rb_get_kwargs(opt, keyword_ids, 0, 3, kwvals);

        if (kwvals[0] != Qundef) full_mark = RTEST(kwvals[0]);
        if (kwvals[1] != Qundef) immediate_mark = RTEST(kwvals[1]);
        if (kwvals[2] != Qundef) immediate_sweep = RTEST(kwvals[2]);
    }

    garbage_collect(objspace, full_mark, immediate_mark, immediate_sweep, GPR_FLAG_METHOD);
    if (!finalizing) finalize_deferred(objspace);

    return Qnil;
}

Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.