How the Garbage Collector Works

The standard CLR uses a generational mark-and-compact GC that performs automatic memory management for objects stored on the managed heap. The GC is considered to be a tracing garbage collector in that it doesn’t interfere with every access to an object, but rather wakes up intermittently and traces the graph of objects stored on the managed heap to determine which objects can be considered garbage and therefore collected.

The GC initiates a garbage collection upon performing a memory allocation (via the new keyword) either after a certain threshold of memory has been allocated, or at other times to reduce the application’s memory footprint. This process can also be initiated manually by calling System.GC.Collect. During a garbage collection, all threads may by frozen (more on this in the next section).