Issue #8122 has been updated by tmm1 (Aman Gupta).

Status changed from Open to Closed
% Done changed from 0 to 100


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Bug #8122: [patch] gc: GC.stat improvements and related cleanup
https://bugs.ruby-lang.org/issues/8122#change-42285

Author: tmm1 (Aman Gupta)
Status: Closed
Priority: Normal
Assignee: ko1 (Koichi Sasada)
Category: core
Target version: current: 2.1.0
ruby -v: ruby 2.1.0dev (2013-03-19 trunk 39816) [x86_64-darwin12.2.1]
Backport: 


I propose 4 related patches below. The end result is more information from GC.stat about mark and sweep activity.

1) Rename heap.free_num to heap.swept_num
    This is a purely cosmetic change, to make the purpose of the variable more clear and avoid problems due to misuse later (like we saw in r39811)
    I considered some other names: heap.freelisted_num, heap.reused_num

2) Add heap.sweep_num
    We already calculate heap.marked_num during mark. This is inverse of marked_num calculated at the end of mark cycle.
    Using this you can monitor progress of sweep cycle: (100% * heap.swept_num / heap.sweep_num)
    I considered also: heap.sweeping_num

3) Remove rest_sweep() from GC.stat
    Currently sweep is a side-effect of GC.stat. It makes GC.stat difficult to use for statistics, because it is not constant time operation.
    Also, after rest_sweep(), heap.swept_num == heap.sweep_num, so GC.stat cannot be used to track progress of sweep cycle.

4) Expose new mark/sweep counters via GC.stat



Author: Aman Gupta <aman / tmm1.net>
Date:   Mon Mar 18 18:11:27 2013 -0700

    rename heap.free_num to heap.swept_num

diff --git a/gc.c b/gc.c
index 635e3ec..f654e19 100644
--- a/gc.c
+++ b/gc.c
@@ -229,7 +229,7 @@ typedef struct rb_objspace {
 	RVALUE *range[2];
 	struct heaps_header *freed;
 	size_t marked_num;
-	size_t free_num;
+	size_t swept_num;
 	size_t free_min;
 	size_t final_num;
 	size_t do_heap_free;
@@ -1434,7 +1434,7 @@ finalize_list(rb_objspace_t *objspace, RVALUE *p)
 	objspace->total_freed_object_num++;
 	if (!FL_TEST(p, FL_SINGLETON)) { /* not freeing page */
             add_slot_local_freelist(objspace, p);
-	    objspace->heap.free_num++;
+	    objspace->heap.swept_num++;
 	}
 	else {
 	    struct heaps_slot *slot = (struct heaps_slot *)(VALUE)RDATA(p)->dmark;
@@ -1921,7 +1921,7 @@ slot_sweep(rb_objspace_t *objspace, struct heaps_slot *sweep_slot)
     }
     gc_clear_slot_bits(sweep_slot);
     if (final_num + freed_num + empty_num == sweep_slot->header->limit &&
-        objspace->heap.free_num > objspace->heap.do_heap_free) {
+        objspace->heap.swept_num > objspace->heap.do_heap_free) {
         RVALUE *pp;
 
         for (pp = deferred_final_list; pp != final; pp = pp->as.free.next) {
@@ -1938,7 +1938,7 @@ slot_sweep(rb_objspace_t *objspace, struct heaps_slot *sweep_slot)
         else {
             sweep_slot->free_next = NULL;
         }
-	objspace->heap.free_num += freed_num + empty_num;
+	objspace->heap.swept_num += freed_num + empty_num;
     }
     objspace->total_freed_object_num += freed_num;
     objspace->heap.final_num += final_num;
@@ -1977,7 +1977,7 @@ before_gc_sweep(rb_objspace_t *objspace)
 	    objspace->heap.do_heap_free = initial_free_min;
     }
     objspace->heap.sweep_slots = heaps;
-    objspace->heap.free_num = 0;
+    objspace->heap.swept_num = 0;
     objspace->heap.free_slots = NULL;
 
     /* sweep unlinked method entries */
@@ -1992,7 +1992,7 @@ after_gc_sweep(rb_objspace_t *objspace)
     size_t inc;
 
     gc_prof_set_malloc_info(objspace);
-    if (objspace->heap.free_num < objspace->heap.free_min) {
+    if (objspace->heap.swept_num < objspace->heap.free_min) {
         set_heaps_increment(objspace);
         heaps_increment(objspace);
     }
@@ -2972,7 +2972,7 @@ rb_gc_force_recycle(VALUE p)
         add_slot_local_freelist(objspace, (RVALUE *)p);
     }
     else {
-	objspace->heap.free_num++;
+	objspace->heap.swept_num++;
         slot = add_slot_local_freelist(objspace, (RVALUE *)p);
         if (slot->free_next == NULL) {
             link_free_heap_slot(objspace, slot);
@@ -3205,7 +3205,7 @@ gc_stat(int argc, VALUE *argv, VALUE self)
     rb_hash_aset(hash, sym_heap_length, SIZET2NUM(objspace->heap.length));
     rb_hash_aset(hash, sym_heap_increment, SIZET2NUM(objspace->heap.increment));
     rb_hash_aset(hash, sym_heap_live_num, SIZET2NUM(objspace_live_num(objspace)));
-    rb_hash_aset(hash, sym_heap_free_num, SIZET2NUM(objspace->heap.free_num));
+    rb_hash_aset(hash, sym_heap_free_num, SIZET2NUM(objspace->heap.swept_num));
     rb_hash_aset(hash, sym_heap_final_num, SIZET2NUM(objspace->heap.final_num));
     rb_hash_aset(hash, sym_total_allocated_object, SIZET2NUM(objspace->total_allocated_object_num));
     rb_hash_aset(hash, sym_total_freed_object, SIZET2NUM(objspace->total_freed_object_num));



Author: Aman Gupta <aman / tmm1.net>
Date:   Mon Mar 18 18:32:58 2013 -0700

    add sweep_num

diff --git a/gc.c b/gc.c
index b911d04..c49f1dd 100644
--- a/gc.c
+++ b/gc.c
@@ -229,6 +229,7 @@ typedef struct rb_objspace {
 	RVALUE *range[2];
 	struct heaps_header *freed;
 	size_t marked_num;
+	size_t sweep_num;
 	size_t swept_num;
 	size_t free_min;
 	size_t final_num;
@@ -2957,6 +2958,7 @@ gc_marks(rb_objspace_t *objspace)
     gc_prof_mark_timer_stop(objspace);
 
     objspace->mark_func_data = prev_mark_func_data;
+    objspace->heap.sweep_num = (heaps_used * HEAP_OBJ_LIMIT) - objspace->heap.marked_num;
 }
 
 /* GC */



Author: Aman Gupta <aman / tmm1.net>
Date:   Mon Mar 18 18:14:10 2013 -0700

    remove rest_sweep side-effect from GC.stat

diff --git a/gc.c b/gc.c
index f654e19..b911d04 100644
--- a/gc.c
+++ b/gc.c
@@ -3197,8 +3197,6 @@ gc_stat(int argc, VALUE *argv, VALUE self)
         hash = rb_hash_new();
     }
 
-    rest_sweep(objspace);
-
     rb_hash_aset(hash, sym_count, SIZET2NUM(objspace->count));
     /* implementation dependent counters */
     rb_hash_aset(hash, sym_heap_used, SIZET2NUM(objspace->heap.used));



Author: Aman Gupta <aman / tmm1.net>
Date:   Mon Mar 18 18:59:50 2013 -0700

    add more stats to GC.stat

diff --git a/gc.c b/gc.c
index c49f1dd..8f458db 100644
--- a/gc.c
+++ b/gc.c
@@ -3174,18 +3174,28 @@ gc_stat(int argc, VALUE *argv, VALUE self)
 {
     rb_objspace_t *objspace = &rb_objspace;
     VALUE hash;
+    size_t total_num, live_num;
     static VALUE sym_count;
     static VALUE sym_heap_used, sym_heap_length, sym_heap_increment;
-    static VALUE sym_heap_live_num, sym_heap_free_num, sym_heap_final_num;
+    static VALUE sym_heap_obj_limit, sym_heap_total_num;
+    static VALUE sym_heap_live_num, sym_heap_empty_num, sym_heap_final_num;
+    static VALUE sym_heap_marked_num, sym_heap_sweep_num, sym_heap_swept_num;
+    static VALUE sym_is_lazy_sweeping;
     static VALUE sym_total_allocated_object, sym_total_freed_object;
     if (sym_count == 0) {
 	sym_count = ID2SYM(rb_intern_const("count"));
 	sym_heap_used = ID2SYM(rb_intern_const("heap_used"));
 	sym_heap_length = ID2SYM(rb_intern_const("heap_length"));
 	sym_heap_increment = ID2SYM(rb_intern_const("heap_increment"));
+	sym_heap_obj_limit = ID2SYM(rb_intern_const("heap_obj_limit"));
+	sym_heap_total_num = ID2SYM(rb_intern_const("heap_total_num"));
 	sym_heap_live_num = ID2SYM(rb_intern_const("heap_live_num"));
-	sym_heap_free_num = ID2SYM(rb_intern_const("heap_free_num"));
+	sym_heap_empty_num = ID2SYM(rb_intern_const("heap_empty_num"));
 	sym_heap_final_num = ID2SYM(rb_intern_const("heap_final_num"));
+	sym_heap_marked_num = ID2SYM(rb_intern_const("heap_marked_num"));
+	sym_heap_sweep_num = ID2SYM(rb_intern_const("heap_sweep_num"));
+	sym_heap_swept_num = ID2SYM(rb_intern_const("heap_swept_num"));
+	sym_is_lazy_sweeping = ID2SYM(rb_intern_const("is_lazy_sweeping"));
 	sym_total_allocated_object = ID2SYM(rb_intern_const("total_allocated_object"));
 	sym_total_freed_object = ID2SYM(rb_intern_const("total_freed_object"));
     }
@@ -3201,12 +3211,21 @@ gc_stat(int argc, VALUE *argv, VALUE self)
 
     rb_hash_aset(hash, sym_count, SIZET2NUM(objspace->count));
     /* implementation dependent counters */
+    total_num = heaps_used * HEAP_OBJ_LIMIT;
+    live_num = objspace_live_num(objspace);
+
     rb_hash_aset(hash, sym_heap_used, SIZET2NUM(objspace->heap.used));
     rb_hash_aset(hash, sym_heap_length, SIZET2NUM(objspace->heap.length));
     rb_hash_aset(hash, sym_heap_increment, SIZET2NUM(objspace->heap.increment));
-    rb_hash_aset(hash, sym_heap_live_num, SIZET2NUM(objspace_live_num(objspace)));
-    rb_hash_aset(hash, sym_heap_free_num, SIZET2NUM(objspace->heap.swept_num));
+    rb_hash_aset(hash, sym_heap_obj_limit, SIZET2NUM(HEAP_OBJ_LIMIT));
+    rb_hash_aset(hash, sym_heap_total_num, SIZET2NUM(total_num));
+    rb_hash_aset(hash, sym_heap_live_num, SIZET2NUM(live_num));
+    rb_hash_aset(hash, sym_heap_empty_num, SIZET2NUM(total_num - live_num));
     rb_hash_aset(hash, sym_heap_final_num, SIZET2NUM(objspace->heap.final_num));
+    rb_hash_aset(hash, sym_is_lazy_sweeping, is_lazy_sweeping(objspace) ? Qtrue : Qfalse);
+    rb_hash_aset(hash, sym_heap_marked_num, SIZET2NUM(objspace->heap.marked_num));
+    rb_hash_aset(hash, sym_heap_swept_num, SIZET2NUM(objspace->heap.swept_num));
+    rb_hash_aset(hash, sym_heap_sweep_num, SIZET2NUM(objspace->heap.sweep_num));
     rb_hash_aset(hash, sym_total_allocated_object, SIZET2NUM(objspace->total_allocated_object_num));
     rb_hash_aset(hash, sym_total_freed_object, SIZET2NUM(objspace->total_freed_object_num));
 



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