Problem

We have had a few customers run into this issue where they are using the J# ThreadEnd objects and see problems with the GC running a lot.  If you look at the actual callstack that is calling the GC, it will be the finalizer thread cleaning up this ThreadEnd as we see here:

0:036> k
Child-SP RetAddr           Call Site
05cef478 00000000`1bf31dc5 mscorwks!GCInterface::CollectGeneration
05cef480 00000642`7f66bdc6 vjslib_ni!com.ms.vjsharp.lang.ThreadEnd.Finalize()+0x35
05cef4e0 00000642`7f4ebf2b mscorwks!FastCallFinalizeWorker+0x6 
05cef510 00000642`7f4ec075 mscorwks!FastCallFinalize+0xbb 
05cef590 00000642`7f4f16e2 mscorwks!MethodTable::CallFinalizer+0x69 
05cef5e0 00000642`7f4f1524 mscorwks!SVR::CallFinalizer+0x72 
05cef640 00000642`7f4f146b mscorwks!SVR::DoOneFinalization+0x84 
05cef700 00000642`7f61fb1b mscorwks!SVR::FinalizeAllObjects+0x9b
05cef7c0 00000642`7f5264cc mscorwks!SVR::FinalizeAllObjects_Wrapper+0x1b
05cef7f0 00000642`7f52693d mscorwks!ManagedThreadBase_DispatchMiddle+0x12c 
05cef900 00000642`7f608455 mscorwks!ManagedThreadBase_DispatchOuter+0x31 
05cef940 00000642`7f4a71bc mscorwks!ManagedThreadBase_DispatchInCorrectAD+0x15
05cef970 00000642`7f44b939 mscorwks!Thread::DoADCallBack+0xd0
05cefab0 00000642`7f4f15f6 mscorwks!ManagedThreadBase_DispatchInner+0x51 
05cefb00 00000642`7f4f146b mscorwks!SVR::DoOneFinalization+0x156 
05cefbc0 00000642`7f4b679d mscorwks!SVR::FinalizeAllObjects+0x9b 
05cefc80 00000642`7f5264cc mscorwks!SVR::GCHeap::FinalizerThreadWorker+0xbd
05cefcc0 00000642`7f52693d mscorwks!ManagedThreadBase_DispatchMiddle+0x12c
05cefdd0 00000642`7f463c36 mscorwks!ManagedThreadBase_DispatchOuter+0x31
05cefe10 00000642`7f4b6d64 mscorwks!ManagedThreadBase_NoADTransition+0x42

From this we can see that the Finalize method of ThreadEnd is calling the collection.  This is something that these threads do.

Workaround

The only way around this, if this is causing a problem, is to switch from using Java threads to .NET Threads instead as they don't call GC.Collect().

This problem has been mentioned a few times, including on Maoni's blog