On inspecting a crash dump file for an out of memory exception reported by a client the results of !DumpHeap -stat
showed that 575MB of memory is being taken up by 45,000 objects of type "Free" most of which I assume would have to reside in Gen 2 due to the size.
The first places I looked for problems were the large object heap (LOH) and pinned objects. The large object heap with free space included was only 70MB so that wasn't the issue and running !gchandles
showed:
GC Handle Statistics:
Strong Handles: 155
Pinned Handles: 265
Async Pinned Handles: 8
Ref Count Handles: 163
Weak Long Handles: 0
Weak Short Handles: 0
Other Handles: 0
which is a very small number of handles (around 600) compared to the number of free objects (45,000). To me this rules out the free blocks being caused by pinning.
I also looked into the free blocks themselves to see if maybe they had a consistent size, but on inspection the sizes varied widely and went from just short of 5MB to only around 12 bytes or so.
Any help would be appreciated! I am at a loss since there is fragmentation but no signs of it being cause by the two places that I know to look which are the large object heap (LOH) and pinned handles.