When does the .NET Compact Framework Garbage Collector run

1. Out of memory condition:
   When the system fails to allocate or re-allocate memory a full GC is run to free up as much as possible and then allocation is re-attempted once more before giving up
2. After some significant allocation:
   If one megabyte of memory is allocated since the last garbage collection then GC is fired.
3. Failure of allocating some native resources: Internally .NET uses various native resources. Some native resource allocation can fail due to memory issues and GC is run before re-attempting
4. Profiler:
   Profiler APIs build into the framework can force a GC
5. Forced GC:
   System.GC class is provided in the BCL to force a collection
6. Application moves to background
   When the given application is moved to background collection is run