Module: ObjectSpace

Defined in:
gc.c,
gc.c

Overview

The ObjectSpace module contains a number of routines

that interact with the garbage collection facility and allow you to
traverse all living objects with an iterator.

ObjectSpace also provides support for object finalizers, procs that will be
called when a specific object is about to be destroyed by garbage
collection.

   a = "A"
   b = "B"

   ObjectSpace.define_finalizer(a, proc {|id| puts "Finalizer one on #{id}" })
   ObjectSpace.define_finalizer(b, proc {|id| puts "Finalizer two on #{id}" })

_produces:_

   Finalizer two on 537763470
   Finalizer one on 537763480

Defined Under Namespace

Classes: WeakMap

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

._id2ref(object_id) ⇒ Object

Converts an object id to a reference to the object. May not be called on an object id passed as a parameter to a finalizer.

s = "I am a string"                    #=> "I am a string"
r = ObjectSpace._id2ref(s.object_id)   #=> "I am a string"
r == s                                 #=> true

Returns:


2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
# File 'gc.c', line 2292

static VALUE
id2ref(VALUE obj, VALUE objid)
{
#if SIZEOF_LONG == SIZEOF_VOIDP
#define NUM2PTR(x) NUM2ULONG(x)
#elif SIZEOF_LONG_LONG == SIZEOF_VOIDP
#define NUM2PTR(x) NUM2ULL(x)
#endif
    rb_objspace_t *objspace = &rb_objspace;
    VALUE ptr;
    void *p0;

    ptr = NUM2PTR(objid);
    p0 = (void *)ptr;

    if (ptr == Qtrue) return Qtrue;
    if (ptr == Qfalse) return Qfalse;
    if (ptr == Qnil) return Qnil;
    if (FIXNUM_P(ptr)) return (VALUE)ptr;
    if (FLONUM_P(ptr)) return (VALUE)ptr;
    ptr = obj_id_to_ref(objid);

    if ((ptr % sizeof(RVALUE)) == (4 << 2)) {
        ID symid = ptr / sizeof(RVALUE);
        if (rb_id2name(symid) == 0)
	    rb_raise(rb_eRangeError, "%p is not symbol id value", p0);
	return ID2SYM(symid);
    }

    if (!is_id_value(objspace, ptr)) {
	rb_raise(rb_eRangeError, "%p is not id value", p0);
    }
    if (!is_live_object(objspace, ptr)) {
	rb_raise(rb_eRangeError, "%p is recycled object", p0);
    }
    return (VALUE)ptr;
}

.count_objects([result_hash]) ⇒ Hash

Counts objects for each type.

It returns a hash, such as:

:TOTAL=>10000,
:FREE=>3011,
:T_OBJECT=>6,
:T_CLASS=>404,
# ...

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

If the optional argument result_hash is given, it is overwritten and returned. This is intended to avoid probe effect.

This method is only expected to work on C Ruby.

Returns:


2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
# File 'gc.c', line 2579

static VALUE
count_objects(int argc, VALUE *argv, VALUE os)
{
    rb_objspace_t *objspace = &rb_objspace;
    size_t counts[T_MASK+1];
    size_t freed = 0;
    size_t total = 0;
    size_t i;
    VALUE hash;

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

    for (i = 0; i <= T_MASK; i++) {
        counts[i] = 0;
    }

    for (i = 0; i < heap_pages_used; i++) {
	struct heap_page *page = heap_pages_sorted[i];
	RVALUE *p, *pend;

	p = page->start; pend = p + page->limit;
	for (;p < pend; p++) {
	    if (p->as.basic.flags) {
		counts[BUILTIN_TYPE(p)]++;
	    }
	    else {
		freed++;
	    }
	}
	total += page->limit;
    }

    if (hash == Qnil) {
        hash = rb_hash_new();
    }
    else if (!RHASH_EMPTY_P(hash)) {
        st_foreach(RHASH_TBL_RAW(hash), set_zero, hash);
    }
    rb_hash_aset(hash, ID2SYM(rb_intern("TOTAL")), SIZET2NUM(total));
    rb_hash_aset(hash, ID2SYM(rb_intern("FREE")), SIZET2NUM(freed));

    for (i = 0; i <= T_MASK; i++) {
        VALUE type;
        switch (i) {
#define COUNT_TYPE(t) case (t): type = ID2SYM(rb_intern(#t)); break;
	    COUNT_TYPE(T_NONE);
	    COUNT_TYPE(T_OBJECT);
	    COUNT_TYPE(T_CLASS);
	    COUNT_TYPE(T_MODULE);
	    COUNT_TYPE(T_FLOAT);
	    COUNT_TYPE(T_STRING);
	    COUNT_TYPE(T_REGEXP);
	    COUNT_TYPE(T_ARRAY);
	    COUNT_TYPE(T_HASH);
	    COUNT_TYPE(T_STRUCT);
	    COUNT_TYPE(T_BIGNUM);
	    COUNT_TYPE(T_FILE);
	    COUNT_TYPE(T_DATA);
	    COUNT_TYPE(T_MATCH);
	    COUNT_TYPE(T_COMPLEX);
	    COUNT_TYPE(T_RATIONAL);
	    COUNT_TYPE(T_NIL);
	    COUNT_TYPE(T_TRUE);
	    COUNT_TYPE(T_FALSE);
	    COUNT_TYPE(T_SYMBOL);
	    COUNT_TYPE(T_FIXNUM);
	    COUNT_TYPE(T_UNDEF);
	    COUNT_TYPE(T_NODE);
	    COUNT_TYPE(T_ICLASS);
	    COUNT_TYPE(T_ZOMBIE);
#undef COUNT_TYPE
          default:              type = INT2NUM(i); break;
        }
        if (counts[i])
            rb_hash_aset(hash, type, SIZET2NUM(counts[i]));
    }

    return hash;
}

.define_finalizer(obj, aProc = proc()) ⇒ Object

Adds aProc as a finalizer, to be called after obj was destroyed.


1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
# File 'gc.c', line 1940

static VALUE
define_final(int argc, VALUE *argv, VALUE os)
{
    VALUE obj, block;

    rb_scan_args(argc, argv, "11", &obj, &block);
    should_be_finalizable(obj);
    if (argc == 1) {
	block = rb_block_proc();
    }
    else {
	should_be_callable(block);
    }

    return define_final0(obj, block);
}

.each_object([) {|obj| ... } ⇒ Fixnum .each_object([) ⇒ Object

Calls the block once for each living, nonimmediate object in this Ruby process. If module is specified, calls the block for only those classes or modules that match (or are a subclass of) module. Returns the number of objects found. Immediate objects (Fixnums, Symbols true, false, and nil) are never returned. In the example below, each_object returns both the numbers we defined and several constants defined in the Math module.

If no block is given, an enumerator is returned instead.

a = 102.7
b = 95       # Won't be returned
c = 12345678987654321
count = ObjectSpace.each_object(Numeric) {|x| p x }
puts "Total count: #{count}"

produces:

12345678987654321
102.7
2.71828182845905
3.14159265358979
2.22044604925031e-16
1.7976931348623157e+308
2.2250738585072e-308
Total count: 7

Overloads:

  • .each_object([) {|obj| ... } ⇒ Fixnum

    Yields:

    • (obj)

    Returns:


1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
# File 'gc.c', line 1873

static VALUE
os_each_obj(int argc, VALUE *argv, VALUE os)
{
    VALUE of;

    if (argc == 0) {
	of = 0;
    }
    else {
	rb_scan_args(argc, argv, "01", &of);
    }
    RETURN_ENUMERATOR(os, 1, &of);
    return os_obj_of(of);
}

.startnil .garbage_collectnil .garbage_collectnil .start(full_mark:false) ⇒ 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)
  • .garbage_collectnil

    Returns:

    • (nil)
  • .start(full_mark:false) ⇒ nil

    Returns:

    • (nil)

5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
# File 'gc.c', line 5143

static VALUE
gc_start_internal(int argc, VALUE *argv, VALUE self)
{
    rb_objspace_t *objspace = &rb_objspace;
    int full_mark = TRUE, immediate_sweep = TRUE;
    VALUE opt = Qnil;
    static ID keyword_ids[2];

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

    if (!NIL_P(opt)) {
	VALUE kwvals[2];

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

	rb_get_kwargs(opt, keyword_ids, 0, 2, kwvals);

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

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

    return Qnil;
}

.undefine_finalizer(obj) ⇒ Object

Removes all finalizers for obj.


1896
1897
1898
1899
1900
# File 'gc.c', line 1896

static VALUE
undefine_final(VALUE os, VALUE obj)
{
    return rb_undefine_finalizer(obj);
}

Instance Method Details

#_id2ref(object_id) ⇒ Object (private)

Converts an object id to a reference to the object. May not be called on an object id passed as a parameter to a finalizer.

s = "I am a string"                    #=> "I am a string"
r = ObjectSpace._id2ref(s.object_id)   #=> "I am a string"
r == s                                 #=> true

Returns:


2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
# File 'gc.c', line 2292

static VALUE
id2ref(VALUE obj, VALUE objid)
{
#if SIZEOF_LONG == SIZEOF_VOIDP
#define NUM2PTR(x) NUM2ULONG(x)
#elif SIZEOF_LONG_LONG == SIZEOF_VOIDP
#define NUM2PTR(x) NUM2ULL(x)
#endif
    rb_objspace_t *objspace = &rb_objspace;
    VALUE ptr;
    void *p0;

    ptr = NUM2PTR(objid);
    p0 = (void *)ptr;

    if (ptr == Qtrue) return Qtrue;
    if (ptr == Qfalse) return Qfalse;
    if (ptr == Qnil) return Qnil;
    if (FIXNUM_P(ptr)) return (VALUE)ptr;
    if (FLONUM_P(ptr)) return (VALUE)ptr;
    ptr = obj_id_to_ref(objid);

    if ((ptr % sizeof(RVALUE)) == (4 << 2)) {
        ID symid = ptr / sizeof(RVALUE);
        if (rb_id2name(symid) == 0)
	    rb_raise(rb_eRangeError, "%p is not symbol id value", p0);
	return ID2SYM(symid);
    }

    if (!is_id_value(objspace, ptr)) {
	rb_raise(rb_eRangeError, "%p is not id value", p0);
    }
    if (!is_live_object(objspace, ptr)) {
	rb_raise(rb_eRangeError, "%p is recycled object", p0);
    }
    return (VALUE)ptr;
}

#count_objects([result_hash]) ⇒ Hash (private)

Counts objects for each type.

It returns a hash, such as:

:TOTAL=>10000,
:FREE=>3011,
:T_OBJECT=>6,
:T_CLASS=>404,
# ...

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

If the optional argument result_hash is given, it is overwritten and returned. This is intended to avoid probe effect.

This method is only expected to work on C Ruby.

Returns:


2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
# File 'gc.c', line 2579

static VALUE
count_objects(int argc, VALUE *argv, VALUE os)
{
    rb_objspace_t *objspace = &rb_objspace;
    size_t counts[T_MASK+1];
    size_t freed = 0;
    size_t total = 0;
    size_t i;
    VALUE hash;

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

    for (i = 0; i <= T_MASK; i++) {
        counts[i] = 0;
    }

    for (i = 0; i < heap_pages_used; i++) {
	struct heap_page *page = heap_pages_sorted[i];
	RVALUE *p, *pend;

	p = page->start; pend = p + page->limit;
	for (;p < pend; p++) {
	    if (p->as.basic.flags) {
		counts[BUILTIN_TYPE(p)]++;
	    }
	    else {
		freed++;
	    }
	}
	total += page->limit;
    }

    if (hash == Qnil) {
        hash = rb_hash_new();
    }
    else if (!RHASH_EMPTY_P(hash)) {
        st_foreach(RHASH_TBL_RAW(hash), set_zero, hash);
    }
    rb_hash_aset(hash, ID2SYM(rb_intern("TOTAL")), SIZET2NUM(total));
    rb_hash_aset(hash, ID2SYM(rb_intern("FREE")), SIZET2NUM(freed));

    for (i = 0; i <= T_MASK; i++) {
        VALUE type;
        switch (i) {
#define COUNT_TYPE(t) case (t): type = ID2SYM(rb_intern(#t)); break;
	    COUNT_TYPE(T_NONE);
	    COUNT_TYPE(T_OBJECT);
	    COUNT_TYPE(T_CLASS);
	    COUNT_TYPE(T_MODULE);
	    COUNT_TYPE(T_FLOAT);
	    COUNT_TYPE(T_STRING);
	    COUNT_TYPE(T_REGEXP);
	    COUNT_TYPE(T_ARRAY);
	    COUNT_TYPE(T_HASH);
	    COUNT_TYPE(T_STRUCT);
	    COUNT_TYPE(T_BIGNUM);
	    COUNT_TYPE(T_FILE);
	    COUNT_TYPE(T_DATA);
	    COUNT_TYPE(T_MATCH);
	    COUNT_TYPE(T_COMPLEX);
	    COUNT_TYPE(T_RATIONAL);
	    COUNT_TYPE(T_NIL);
	    COUNT_TYPE(T_TRUE);
	    COUNT_TYPE(T_FALSE);
	    COUNT_TYPE(T_SYMBOL);
	    COUNT_TYPE(T_FIXNUM);
	    COUNT_TYPE(T_UNDEF);
	    COUNT_TYPE(T_NODE);
	    COUNT_TYPE(T_ICLASS);
	    COUNT_TYPE(T_ZOMBIE);
#undef COUNT_TYPE
          default:              type = INT2NUM(i); break;
        }
        if (counts[i])
            rb_hash_aset(hash, type, SIZET2NUM(counts[i]));
    }

    return hash;
}

#define_finalizer(obj, aProc = proc()) ⇒ Object (private)

Adds aProc as a finalizer, to be called after obj was destroyed.


1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
# File 'gc.c', line 1940

static VALUE
define_final(int argc, VALUE *argv, VALUE os)
{
    VALUE obj, block;

    rb_scan_args(argc, argv, "11", &obj, &block);
    should_be_finalizable(obj);
    if (argc == 1) {
	block = rb_block_proc();
    }
    else {
	should_be_callable(block);
    }

    return define_final0(obj, block);
}

#each_object([) ⇒ Object (private) #each_object([) ⇒ Object (private)

Calls the block once for each living, nonimmediate object in this Ruby process. If module is specified, calls the block for only those classes or modules that match (or are a subclass of) module. Returns the number of objects found. Immediate objects (Fixnums, Symbols true, false, and nil) are never returned. In the example below, each_object returns both the numbers we defined and several constants defined in the Math module.

If no block is given, an enumerator is returned instead.

a = 102.7
b = 95       # Won't be returned
c = 12345678987654321
count = ObjectSpace.each_object(Numeric) {|x| p x }
puts "Total count: #{count}"

produces:

12345678987654321
102.7
2.71828182845905
3.14159265358979
2.22044604925031e-16
1.7976931348623157e+308
2.2250738585072e-308
Total count: 7

Yields:

  • (obj)

    @return [Fixnum]


1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
# File 'gc.c', line 1873

static VALUE
os_each_obj(int argc, VALUE *argv, VALUE os)
{
    VALUE of;

    if (argc == 0) {
	of = 0;
    }
    else {
	rb_scan_args(argc, argv, "01", &of);
    }
    RETURN_ENUMERATOR(os, 1, &of);
    return os_obj_of(of);
}

#startnil (private) #garbage_collectnil (private) #garbage_collectnil (private) #start(full_mark:false) ⇒ nil (private)

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.

Returns:

  • (nil)
  • (nil)
  • (nil)
  • (nil)

5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
# File 'gc.c', line 5143

static VALUE
gc_start_internal(int argc, VALUE *argv, VALUE self)
{
    rb_objspace_t *objspace = &rb_objspace;
    int full_mark = TRUE, immediate_sweep = TRUE;
    VALUE opt = Qnil;
    static ID keyword_ids[2];

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

    if (!NIL_P(opt)) {
	VALUE kwvals[2];

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

	rb_get_kwargs(opt, keyword_ids, 0, 2, kwvals);

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

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

    return Qnil;
}

#undefine_finalizer(obj) ⇒ Object (private)

Removes all finalizers for obj.


1896
1897
1898
1899
1900
# File 'gc.c', line 1896

static VALUE
undefine_final(VALUE os, VALUE obj)
{
    return rb_undefine_finalizer(obj);
}