System::Threading::AotInterlocked SpinLock SpinLock System.Threading.AotInterlocked.spinLock spinLock = new SpinLock(false) T static T System.Threading.AotInterlocked.Exchange< T > (ref T target, T newValue) Exchange< T > ref T target T newValue T static T System.Threading.AotInterlocked.CompareExchange< T > (ref T target, T newValue, T comparand) CompareExchange< T > ref T target T newValue T comparand Interlocked reference exchanges do not work with the older Mono AOT compiler so this type fudges around it using a spinlock. This works (probably more slowly) so long as all exchanges are performed through this mechanism. See AOT compiler fixes: 79b99d358b1321759ea3a42f22eaf141aecf0e79 on the mono 2.10 branch http://permalink.gmane.org/gmane.comp.gnome.mono.patches/182067 https://bugzilla.xamarin.com/show_bug.cgi?id=234 System.Threading.AotInterlocked System::Threading::AotInterlockedCompareExchange< T > System::Threading::AotInterlockedExchange< T > System::Threading::AotInterlockedspinLock