GC is never triggered

[Agis Anastasopoulos]

Using https://github.com/github/ruby/tree/2.1 w/ 4 unicorn workers on a rails app:

$ ab -n300 -c4 http://0.0.0.0:8080/

Workers are GC.disableed after forked. The GC settings are the default ones.

GC is never triggered even though GC::OOB.run is called. Yet memory peeks at 12gb after ~60reqs:

# after the 60th request
GC.stat
# => {:count=>32,
 :heap_used=>59478,
 :heap_length=>59682,
 :heap_increment=>204,
 :heap_live_slot=>24231036,
 :heap_free_slot=>12174,
 :heap_final_slot=>0,
 :heap_swept_slot=>180347,
 :heap_eden_page_length=>59478,
 :heap_tomb_page_length=>0,
 :total_allocated_object=>28445740,
 :total_freed_object=>4214704,
 :malloc_increase=>698054064,
 :malloc_limit=>14000000,
 :minor_gc_count=>25,
 :major_gc_count=>7,
 :remembered_shady_object=>5569,
 :remembered_shady_object_limit=>9834,
 :old_object=>357190,
 :old_object_limit=>589654,
 :oldmalloc_increase=>589477296,
 :oldmalloc_limit=>22319355}

After the 300th req:

GC.stat
# => {:count=>32,
 :heap_used=>277812,
 :heap_length=>277977,
 :heap_increment=>165,
 :heap_live_slot=>113224475,
 :heap_free_slot=>11710,
 :heap_final_slot=>0,
 :heap_swept_slot=>180355,
 :heap_eden_page_length=>277812,
 :heap_tomb_page_length=>0,
 :total_allocated_object=>117439030,
 :total_freed_object=>4214555,
 :malloc_increase=>3116922544,
 :malloc_limit=>14000000,
 :minor_gc_count=>25,
 :major_gc_count=>7,
 :remembered_shady_object=>5571,
 :remembered_shady_object_limit=>9834,
 :old_object=>357202,
 :old_object_limit=>589622,
 :oldmalloc_increase=>2613982896,
 :oldmalloc_limit=>22319355}

Also tried with a smaller MALLOC_LIMIT, no luck.

[Aman Karmani]

Why are you calling GC.disable? I don't think OOB handles the disabled GC case.

[Agis Anastasopoulos]

Ah my bad, ignore this.