6786346: intermittent Internal Error (src/share/vm/memory/cardTableModRefBS.cpp:226)
Summary: Two assertions were incorrectly composed.
Reviewed-by: tonyp
--- a/hotspot/src/share/vm/memory/cardTableModRefBS.cpp Tue Feb 10 18:39:09 2009 +0300
+++ b/hotspot/src/share/vm/memory/cardTableModRefBS.cpp Tue Feb 17 15:35:58 2009 -0800
@@ -217,15 +217,28 @@
(HeapWord*) align_size_up((uintptr_t)new_end, _page_size);
assert(new_end_aligned >= (HeapWord*) new_end,
"align up, but less");
+ // Check the other regions (excludes "ind") to ensure that
+ // the new_end_aligned does not intrude onto the committed
+ // space of another region.
int ri = 0;
for (ri = 0; ri < _cur_covered_regions; ri++) {
if (ri != ind) {
if (_committed[ri].contains(new_end_aligned)) {
- assert((new_end_aligned >= _committed[ri].start()) &&
- (_committed[ri].start() > _committed[ind].start()),
+ // The prior check included in the assert
+ // (new_end_aligned >= _committed[ri].start())
+ // is redundant with the "contains" test.
+ // Any region containing the new end
+ // should start at or beyond the region found (ind)
+ // for the new end (committed regions are not expected to
+ // be proper subsets of other committed regions).
+ assert(_committed[ri].start() >= _committed[ind].start(),
"New end of committed region is inconsistent");
new_end_aligned = _committed[ri].start();
- assert(new_end_aligned > _committed[ind].start(),
+ // new_end_aligned can be equal to the start of its
+ // committed region (i.e., of "ind") if a second
+ // region following "ind" also start at the same location
+ // as "ind".
+ assert(new_end_aligned >= _committed[ind].start(),
"New end of committed region is before start");
debug_only(collided = true;)
// Should only collide with 1 region