Fix mark stack excessive growth during parallel mark

(The growth observed in applications that implement things like weak
hash tables and iterate over the members marking entries using the
supplied GC_MARK_AND_PUSH macro.)

When overflow is signaled, only set GC_mark_stack_too_small if we
are using the global mark stack.  In parallel mode, local mark stack
is used, so the global mark stack is grown by GC_return_mark_stack
mainly.

* mark.c (GC_signal_mark_stack_overflow): Do not set
GC_mark_stack_too_small if GC_parallel.

diff --git a/mark.c b/mark.c
index 60a1a1e48dfcb956236667e62b1fbc0b826e040a..6e594804513ddcb147ad3c04f7c6b1a28c25158c 100644 (file)
--- a/mark.c
+++ b/mark.c
@@ -576,7 +576,15 @@ GC_INNER void GC_invalidate_mark_state(void)
 GC_INNER mse * GC_signal_mark_stack_overflow(mse *msp)
 {
     GC_mark_state = MS_INVALID;
-    GC_mark_stack_too_small = TRUE;
+#   ifdef PARALLEL_MARK
+      /* We are using a local_mark_stack in parallel mode, so   */
+      /* do not signal the global mark stack to be resized.     */
+      /* That will be done if required in GC_return_mark_stack. */
+      if (!GC_parallel)
+        GC_mark_stack_too_small = TRUE;
+#   else
+      GC_mark_stack_too_small = TRUE;
+#   endif
     GC_COND_LOG_PRINTF("Mark stack overflow; current size = %lu entries\n",
                        (unsigned long)GC_mark_stack_size);
     return(msp - GC_MARK_STACK_DISCARDS);