merge revision(s) 49474,49541,49545,49684: [Backport #10768]

	* gc.c (rb_objspace_free): cause rb_bug if lazy sweep is in progress
	  during rb_objspace_free. Adds extra protection for r46340.
	  Patch by Vicent Marti. [Bug #10768] [ruby-core:67734]

	* gc.c (rb_objspace_call_finalizer): Ensure GC is completed after
	  finalizers have run. We already call gc_rest() before invoking
	  finalizers, but finalizer can allocate new objects and start new GC
	  cycle, so we call gc_rest() again after finalizers are complete.

	* gc.c (rb_objspace_call_finalizer): control GC execution during
	  force firnalizations at the end of interpreter process.
	  [Bug #10768]
	  1) Prohibit incremental GC while running Ruby-level finalizers
	     to avoid any danger.
	  2) Prohibit GC while invoking T_DATA/T_FILE data structure
	     because these operations break object relations consistency.
	  This patch can introduce another memory consuming issue because
	  Ruby-level finalizers can run after (2), GC is disabled.
	  However, basically object consistency was broken at (2) as I
	  described above. So that running Ruby-level finalizers contains
	  danger originally. Because of this point, I need to suggest to
	  remove these 3 lines (invoking remaining finalizers). And add a
	  rule to add that finalizers should not add new finalizers, or
	  say there is no guarantee to invoke finalizers that added by
	  another finalizer.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@49716 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 12 insertions, 2 deletions

diff --git a/gc.c b/gc.c
index 5f67bdec29..c84da503ea 100644
--- a/gc.c
+++ b/gc.c
@@ -1209,6 +1209,9 @@ static void heap_page_free(rb_objspace_t *objspace, struct heap_page *page);
 void
 rb_objspace_free(rb_objspace_t *objspace)
 {
+    if (is_lazy_sweeping(heap_eden))
+	rb_bug("lazy sweeping underway when freeing object space");
+
     if (objspace->profile.records) {
 	free(objspace->profile.records);
 	objspace->profile.records = 0;
@@ -2563,6 +2566,10 @@ rb_objspace_call_finalizer(rb_objspace_t *objspace)
     finalize_deferred(objspace);
     assert(heap_pages_deferred_final == 0);
 
+    gc_rest(objspace);
+    /* prohibit incremental GC */
+    objspace->flags.dont_incremental = 1;
+
     /* force to run finalizer */
     while (finalizer_table->num_entries) {
 	struct force_finalize_list *list = 0;
@@ -2577,10 +2584,13 @@ rb_objspace_call_finalizer(rb_objspace_t *objspace)
 	}
     }
 
-    /* finalizers are part of garbage collection */
+    /* prohibit GC because force T_DATA finalizers can break an object graph consistency */
+    dont_gc = 1;
+
+    /* running data/file finalizers are part of garbage collection */
     gc_enter(objspace, "rb_objspace_call_finalizer");
 
-    /* run data object's finalizers */
+    /* run data/file object's finalizers */
     for (i = 0; i < heap_allocated_pages; i++) {
 	p = heap_pages_sorted[i]->start; pend = p + heap_pages_sorted[i]->total_slots;
 	while (p < pend) {