src/hotspot/share/gc/shenandoah/shenandoahMemoryPool.cpp

rev 53841 : 8219524: Shenandoah misreports "committed" size in MemoryMXBean
Reviewed-by: XXX

@@ -24,23 +24,29 @@
 #include "precompiled.hpp"
 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
 
 ShenandoahMemoryPool::ShenandoahMemoryPool(ShenandoahHeap* heap) :
         CollectedMemoryPool("Shenandoah",
-                            heap->capacity(),
+                            heap->initial_capacity(),
                             heap->max_capacity(),
                             true /* support_usage_threshold */),
                             _heap(heap) {}
 
 MemoryUsage ShenandoahMemoryPool::get_memory_usage() {
   size_t initial   = initial_size();
   size_t max       = max_size();
   size_t used      = used_in_bytes();
   size_t committed = _heap->committed();
 
+  // These asserts can never fail: max is stable, and all updates to other values never overflow max.
   assert(initial <= max,    "initial: "   SIZE_FORMAT ", max: "       SIZE_FORMAT, initial,   max);
   assert(used <= max,       "used: "      SIZE_FORMAT ", max: "       SIZE_FORMAT, used,      max);
   assert(committed <= max,  "committed: " SIZE_FORMAT ", max: "       SIZE_FORMAT, committed, max);
+
+  // Committed and used are updated concurrently and independently. They can momentarily break
+  // the assert below, which would also fail in downstream code. To avoid that, adjust values
+  // to make sense under the race. See JDK-8207200.
+  committed = MAX2(used, committed);
   assert(used <= committed, "used: "      SIZE_FORMAT ", committed: " SIZE_FORMAT, used,      committed);
 
   return MemoryUsage(initial, used, committed, max);
 }