Module: GC

Defined in:
gc.c

Overview

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.

Defined Under Namespace

Modules: Profiler

Constant Summary collapse

INTERNAL_CONSTANTS =
gc_constants
OPTS =
opts = rb_ary_new()

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.add_stress_to_class(*args) ⇒ Object


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# File 'gc.c', line 9187

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

    if (!stress_to_class) {
	stress_to_class = rb_ary_tmp_new(argc);
    }
    rb_ary_cat(stress_to_class, argv, argc);
    return self;
}

.countInteger

The number of times GC occurred.

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

Returns:


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# File 'gc.c', line 6536

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

.disableBoolean

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

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

Returns:

  • (Boolean)

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# File 'gc.c', line 7148

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;
}

.enableBoolean

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

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

Returns:

  • (Boolean)

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# File 'gc.c', line 7126

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

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

.latest_gc_infoObject .latest_gc_info(hash) ⇒ Hash .latest_gc_info(: major_by) ⇒ Object

Returns information about the most recent garbage collection.

Overloads:

  • .latest_gc_info(hash) ⇒ Hash

    Returns:


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# File 'gc.c', line 6651

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_sizeInteger

Returns the size of memory allocated by malloc().

Only available if ruby was built with CALC_EXACT_MALLOC_SIZE.

Returns:


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# File 'gc.c', line 7872

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

.malloc_allocationsInteger

Returns the number of malloc() allocations.

Only available if ruby was built with CALC_EXACT_MALLOC_SIZE.

Returns:


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# File 'gc.c', line 7887

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

.remove_stress_to_class(*args) ⇒ Object


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# File 'gc.c', line 9199

static VALUE
rb_gcdebug_remove_stress_to_class(int argc, VALUE *argv, VALUE self)
{
    rb_objspace_t *objspace = &rb_objspace;
    int i;

    if (stress_to_class) {
	for (i = 0; i < argc; ++i) {
	    rb_ary_delete_same(stress_to_class, argv[i]);
	}
	if (RARRAY_LEN(stress_to_class) == 0) {
	    stress_to_class = 0;
	}
    }
    return Qnil;
}

.startnil .garbage_collectnil .start(full_mark: true, immediate_sweep: true) ⇒ nil .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.

Overloads:

  • .startnil

    Returns:

    • (nil)
  • .garbage_collectnil

    Returns:

    • (nil)
  • .start(full_mark: true, immediate_sweep: true) ⇒ nil

    Returns:

    • (nil)
  • .garbage_collect(full_mark: true, immediate_sweep: true) ⇒ nil

    Returns:

    • (nil)

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# File 'gc.c', line 6449

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;
}

.statHash .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.

Overloads:


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# File 'gc.c', line 7032

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;
}

.stressBoolean

Returns current status of GC stress mode.

Returns:

  • (Boolean)

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# File 'gc.c', line 7074

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

.stress=(flag) ⇒ Object

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

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# File 'gc.c', line 7105

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

.verify_internal_consistencynil

Verify internal consistency.

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

Returns:

  • (nil)

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# File 'gc.c', line 5086

static VALUE
gc_verify_internal_consistency(VALUE dummy)
{
    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.uncollectible_wb_unprotected_objects != data.remembered_shady_count) {
	    rb_bug("inconsistent old slot nubmer: expect %"PRIuSIZE", but %"PRIuSIZE".", objspace->rgengc.uncollectible_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;
}

Instance Method Details

#startnil #garbage_collectnil #start(full_mark: true, immediate_sweep: true) ⇒ nil #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.

Overloads:

  • #startnil

    Returns:

    • (nil)
  • #garbage_collectnil

    Returns:

    • (nil)
  • #start(full_mark: true, immediate_sweep: true) ⇒ nil

    Returns:

    • (nil)
  • #garbage_collect(full_mark: true, immediate_sweep: true) ⇒ nil

    Returns:

    • (nil)

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# File 'gc.c', line 6449

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;
}