mutex_alloc      2913 thread.c           return mutex_alloc(rb_cMutex);
mutex_alloc      3236 thread.c           return Data_Wrap_Struct(klass, rb_gc_mark, 0, (void *)mutex_alloc(0));
mutex_alloc      3757 thread.c           rb_define_alloc_func(rb_cMutex, mutex_alloc);