How to inspect pinned objects in dotMemory?

Background

In .NET applications, the Garbage Collector (GC) typically moves objects around in memory to prevent fragmentation. However, objects can be "pinned" in place, preventing the GC from relocating them. Excessive pinning can lead to heap fragmentation and application performance degradation.

Question

How can one investigate pinned objects using dotMemory

Answer

Follow the steps below to inspect pinned objects in dotMemory:

1. Open a memory snapshot in dotMemory

   • dotMemory will open an Inspections tab by default

2. Scroll down to the Heap fragmentation section

3. Click on the Pinned objects to open pinned object set

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4. Switch to Instances tab

   

5. Double-click on an instance or use Open this instance context action to inspect specific pinned object instance

   • To understand why an object is being pinned, one might need to inspect Key Retention Paths and/or Creation Stack Trace by switching to corresponding tabs in the instance view