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  • ruby-3.1.2/gc.c
  • ruby-3.1.2/gc.rb

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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

internal constants

OPTS

GC build options

Public Class Methods

add_stress_to_class(class[, ...]) click to toggle source

Raises NoMemoryError when allocating an instance of the given classes.

 
               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;
}
            
auto_compact → true or false click to toggle source

Returns whether or not automatic compaction has been enabled.

 
               # File ruby-3.1.2/gc.rb, line 46
def self.auto_compact
  Primitive.gc_get_auto_compact
end
            
auto_compact = flag click to toggle source

Updates automatic compaction mode.

When enabled, the compactor will execute on every major collection.

Enabling compaction will degrade performance on major collections.

 
               # File ruby-3.1.2/gc.rb, line 58
def self.auto_compact=(flag)
  Primitive.gc_set_auto_compact(flag)
end
            
compact click to toggle source

This function compacts objects together in Ruby's heap. It eliminates unused space (or fragmentation) in the heap by moving objects in to that unused space. This function returns a hash which contains statistics about which objects were moved. See `GC.latest_gc_info` for details about compaction statistics.

This method is implementation specific and not expected to be implemented in any implementation besides MRI.

 
               # File ruby-3.1.2/gc.rb, line 238
def self.compact
  Primitive.gc_compact
end
            
count → Integer click to toggle source

The number of times GC occurred.

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

 
               # File ruby-3.1.2/gc.rb, line 120
def self.count
  Primitive.gc_count
end
            
disable → true or false click to toggle source

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

GC.disable   #=> false
GC.disable   #=> true
 
               # File ruby-3.1.2/gc.rb, line 84
def self.disable
  Primitive.gc_disable
end
            
enable → true or false click to toggle source

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

GC.disable   #=> false
GC.enable    #=> true
GC.enable    #=> false
 
               # File ruby-3.1.2/gc.rb, line 72
def self.enable
  Primitive.gc_enable
end
            
latest_compact_info → {:considered=>{:T_CLASS=>11}, :moved=>{:T_CLASS=>11}} click to toggle source
Returns information about object moved in the most recent GC compaction.

The returned hash has two keys :considered and :moved. The hash for :considered lists the number of objects that were considered for movement by the compactor, and the :moved hash lists the number of objects that were actually moved. Some objects can't be moved (maybe they were pinned) so these numbers can be used to calculate compaction efficiency.

 
               # File ruby-3.1.2/gc.rb, line 223
def self.latest_compact_info
  Primitive.gc_compact_stats
end
            
latest_gc_info → {:gc_by=>:newobj} click to toggle source
latest_gc_info(hash) → hash
latest_gc_info(:major_by) → :malloc
Returns information about the most recent garbage collection.

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

 
               # File ruby-3.1.2/gc.rb, line 209
def self.latest_gc_info hash_or_key = nil
  Primitive.gc_latest_gc_info hash_or_key
end
            
malloc_allocated_size → Integer click to toggle 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 click to toggle 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);
}
            
measure_total_time → true/false click to toggle source

Return measure_total_time flag (default: true). Note that measurement can affect the application performance.

 
               # File ruby-3.1.2/gc.rb, line 288
def self.measure_total_time
  Primitive.cexpr! %{
    RBOOL(rb_objspace.flags.measure_gc)
  }
end
            
measure_total_time = true/false click to toggle source

Enable to measure GC time. You can get the result with GC.stat(:time). Note that GC time measurement can cause some performance overhead.

 
               # File ruby-3.1.2/gc.rb, line 276
def self.measure_total_time=(flag)
  Primitive.cstmt! %{
    rb_objspace.flags.measure_gc = RTEST(flag) ? TRUE : FALSE;
    return flag;
  }
end
            
remove_stress_to_class(class[, ...]) click to toggle source

No longer raises NoMemoryError when allocating an instance of the given classes.

 
               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;
}
            
start → nil click to toggle source
garbage_collect → nil
include GC; garbage_collect → nil
start(full_mark: true, immediate_sweep: true) → nil
garbage_collect(full_mark: true, immediate_sweep: true) → nil
include GC; garbage_collect(full_mark: true, immediate_sweep: true) → nil

Initiates garbage collection, even if 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.

 
               # File ruby-3.1.2/gc.rb, line 33
def self.start full_mark: true, immediate_mark: true, immediate_sweep: true
  Primitive.gc_start_internal full_mark, immediate_mark, immediate_sweep, false
end
            
stat → Hash click to toggle source
stat(hash) → Hash
stat(:key) → Numeric

Returns a Hash containing information about the GC.

The contents of the hash are implementation specific and may change in the future without notice.

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

count

The total number of garbage collections ran since application start (count includes both minor and major garbage collections)

heap_allocated_pages

The total number of `:heap_eden_pages` + `:heap_tomb_pages`

heap_sorted_length

The number of pages that can fit into the buffer that holds references to all pages

heap_allocatable_pages

The total number of pages the application could allocate without additional GC

heap_available_slots

The total number of slots in all `:heap_allocated_pages`

heap_live_slots

The total number of slots which contain live objects

heap_free_slots

The total number of slots which do not contain live objects

heap_final_slots

The total number of slots with pending finalizers to be run

heap_marked_slots

The total number of objects marked in the last GC

heap_eden_pages

The total number of pages which contain at least one live slot

heap_tomb_pages

The total number of pages which do not contain any live slots

total_allocated_pages

The cumulative number of pages allocated since application start

total_freed_pages

The cumulative number of pages freed since application start

total_allocated_objects

The cumulative number of objects allocated since application start

total_freed_objects

The cumulative number of objects freed since application start

malloc_increase_bytes

Amount of memory allocated on the heap for objects. Decreased by any GC

malloc_increase_bytes_limit

When `:malloc_increase_bytes` crosses this limit, GC is triggered

minor_gc_count

The total number of minor garbage collections run since process start

major_gc_count

The total number of major garbage collections run since process start

remembered_wb_unprotected_objects

The total number of objects without write barriers

remembered_wb_unprotected_objects_limit

When `:remembered_wb_unprotected_objects` crosses this limit, major GC is triggered

old_objects

Number of live, old objects which have survived at least 3 garbage collections

old_objects_limit

When `:old_objects` crosses this limit, major GC is triggered

oldmalloc_increase_bytes

Amount of memory allocated on the heap for objects. Decreased by major GC

oldmalloc_increase_bytes_limit

When `:old_malloc_increase_bytes` crosses this limit, major GC is triggered

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

This method is only expected to work on CRuby.

 
               # File ruby-3.1.2/gc.rb, line 195
def self.stat hash_or_key = nil
  Primitive.gc_stat hash_or_key
end
            
stress → integer, true or false click to toggle source

Returns current status of GC stress mode.

 
               # File ruby-3.1.2/gc.rb, line 92
def self.stress
  Primitive.gc_stress_get
end
            
stress = flag → flag click to toggle 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 an integer bit-ORed following flags.

0x01:: no major GC
0x02:: no immediate sweep
0x04:: full mark after malloc/calloc/realloc
 
               # File ruby-3.1.2/gc.rb, line 110
def self.stress=(flag)
  Primitive.gc_stress_set_m flag
end
            
total_time → int click to toggle source

Return measured GC total time in nano seconds.

 
               # File ruby-3.1.2/gc.rb, line 298
def self.total_time
  Primitive.cexpr! %{
    ULL2NUM(rb_objspace.profile.total_time_ns)
  }
end
            
verify_compaction_references(toward: nil, double_heap: false) → hash click to toggle source

Verify compaction reference consistency.

This method is implementation specific. During compaction, objects that were moved are replaced with T_MOVED objects. No object should have a reference to a T_MOVED object after compaction.

This function doubles the heap to ensure room to move all objects, compacts the heap to make sure everything moves, updates all references, then performs a full GC. If any object contains a reference to a T_MOVED object, that object should be pushed on the mark stack, and will make a SEGV.

 
               # File ruby-3.1.2/gc.rb, line 256
def self.verify_compaction_references(toward: nil, double_heap: false)
  Primitive.gc_verify_compaction_references(double_heap, toward == :empty)
end
            
verify_internal_consistency → nil click to toggle 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_m(VALUE dummy)
{
    gc_verify_internal_consistency(&rb_objspace);
    return Qnil;
}
            
verify_transient_heap_internal_consistency() click to toggle source
 
               static VALUE
gc_verify_transient_heap_internal_consistency(VALUE dmy)
{
    rb_transient_heap_verify();
    return Qnil;
}
            

Public Instance Methods

garbage_collect(full_mark: true, immediate_mark: true, immediate_sweep: true) click to toggle source
 
               # File ruby-3.1.2/gc.rb, line 37
def garbage_collect full_mark: true, immediate_mark: true, immediate_sweep: true
  Primitive.gc_start_internal full_mark, immediate_mark, immediate_sweep, false
end