How does Garbage collector know when to clean the objects ?

Question

On which basis it collects objects.

Tuhin Paul · Answer

Part -2 Supporting code in c#: using System; using System.Collections.Concurrent; using System.Diagnostics; using System.Threading.Tasks; public class DataProcessor { // Concurrent queue to simulate high-volume data processing private ConcurrentQueue _dataQueue = new ConcurrentQueue (); // Simulates creating large number of objects public async Task ProcessLargeDataSetAsync(int totalObjects) { Console.WriteLine($"Starting to process {totalObjects} objects"); // Measure memory and time var startMemory = Process.GetCurrentProcess().WorkingSet64; var stopwatch = Diagnostics.Stopwatch.StartNew(); // Parallel processing to create objects quickly await Task.Run(() => { Parallel.For(0, totalObjects, i => { // Create a new data point and add to queue var dataPoint = new DataPoint { Id = i, Timestamp = DateTime.Now, Value = CalculateComplexValue(i) }; _dataQueue.Enqueue(dataPoint); }); }); // Process and potentially remove references ProcessQueue(); stopwatch.Stop(); var endMemory = Process.GetCurrentProcess().WorkingSet64; Console.WriteLine($"Processing complete:"); Console.WriteLine($"Total Time: {stopwatch.ElapsedMilliseconds} ms"); Console.WriteLine($"Memory Used: {(endMemory - startMemory) / 1024 / 1024} MB"); } private void ProcessQueue() { while (_dataQueue.TryDequeue(out var dataPoint)) { // Process the data point ProcessDataPoint(dataPoint); } } private double CalculateComplexValue(int index) { // Simulate complex calculation return Math.Sqrt(index) * Math.Sin(index) * Math.Cos(index); } private void ProcessDataPoint(DataPoint dataPoint) { // Simulate processing // This method creates an opportunity for garbage collection var processedValue = dataPoint.Value * 2; } } // Simple data structure to represent processed data public class DataPoint { public int Id { get; set; } public DateTime Timestamp { get; set; } public double Value { get; set; } } class Program { static async Task Main() { var processor = new DataProcessor(); // Process 1 million objects await processor.ProcessLargeDataSetAsync(1_000_000); // Explicitly trigger garbage collection (not typically needed) GC.Collect(); GC.WaitForPendingFinalizers(); } }

Tuhin Paul · Answer

Part -1 In C#, the Garbage Collector (GC) uses a process called "Mark and Sweep" to identify and clean up objects that are no longer in use. The Garbage Collector primarily uses reachability as the key criterion for collecting objects. An object is considered eligible for garbage collection when it becomes unreachable, meaning: No live references point to the object The object cannot be accessed through any root references (static variables, local variables on the stack, active references in running threads) C# uses a generational garbage collection strategy: Generation 0 : Short-lived objects (most newly created objects) Generation 1 : Objects that survived one collection Generation 2 : Long-lived objects (older objects that have survived multiple collections) let say there is a memory-intensive application that creates numerous objects rapidly. Garbage Collection Mechanisms in this Scenario Object Creation : In the example, we're creating 1 million DataPoint objects quickly using Parallel.For() . Memory Management : As objects are created, they initially populate Generation 0 When Generation 0 becomes full, Garbage Collector triggers Short-lived objects (like our DataPoint instances) are quickly collected Objects that survive multiple collections move to Generation 1 and then Generation 2 Key Garbage Collection Strategies : Concurrent Collection : GC runs concurrently with the application Generational Collection : Different strategies for short-lived vs. long-lived objects Mark and Sweep : Identifies unreachable objects and frees memory To improve performance in scenarios with many object creations: Use object pooling Minimize object allocations Use value types when possible Implement IDisposable for large objects Use using statements for automatic resource management The example demonstrates: Parallel object creation Memory tracking Potential for high-volume object processing Implicit garbage collection management GC is triggered when: Allocation pressure reaches a threshold System memory is low Explicit GC.Collect() is called (rare and not recommended in production)

Mahesh Chand · Answer

in its simplest form, GC watches memory and use of objects. If your machine is running out of memory, it will look for unused or never used objects and their storage and clears that storage.

How does Garbage collector know when to clean the objects ?

Answers (3)