See JDK-8147481.

We need a simplified version of the following patch to log the last few entries of the "phe" structure. This information is useful in conclusively identify spurious errors reported by HealWalk/HeapValidate.

=================
 static int mallocDebugIntervalCounter = 0;
 static int mallocDebugCounter = 0;
 bool os::check_heap(bool force) {
+#define SAVE_COUNT 100000
+ static PROCESS_HEAP_ENTRY saved[SAVE_COUNT];
+
   if (++mallocDebugCounter < MallocVerifyStart && !force) return true;
   if (++mallocDebugIntervalCounter >= MallocVerifyInterval || force) {
     // Note: HeapValidate executes two hardware breakpoints when it finds something
@@ -5242,9 +5245,14 @@
     // or some other special heap flag has been set that prevents
     // locking. We don't try to walk a heap we can't lock.
     if (HeapLock(heap) != 0) {
+ memset(saved, 0, sizeof(saved));
       PROCESS_HEAP_ENTRY phe;
       phe.lpData = NULL;
+ int saved_index = 0;
       while (HeapWalk(heap, &phe) != 0) {
+ if (saved_index < SAVE_COUNT) {
+ saved[saved_index++] = phe;
+ }
         if ((phe.wFlags & PROCESS_HEAP_ENTRY_BUSY) &&
             !HeapValidate(heap, 0, phe.lpData)) {
           tty->print_cr("C heap has been corrupted (time: %d allocations)", mallocDebugCounter);