Does passing an Action as a parameter create garbage?

Question

I'm using a "timer" script that takes an action as a parameter. The script calls the Action when the timer is complete. Does passing an action in a parameter create garbage? I use this a lot and im getting a bunch of GC.Collect() calls in the profiler and it's coming from my timer classes.

Here's what it looks like:

 public class Timer : MonoBehaviour
 {
     private float _timer;
     private float _maxTime;
     public void StartTimer(float time, Action callback) 
     { 
          _timer = 0;
         _maxTime = time;
         TimerCompleteCallback = callback;  
     }
     ////////// Some update code //////////////////////
     void TimerEnd() 
     {  
         this.enabled = false;
         TimerCompleteCallback();
     }
 }
 
 public class OtherClass : MonoBehaviour
 {
      private Timer _timer;
      void Start()
      {
          _timer = gameObject.AddComponent<Timer>();
          _timer.StartTimer(5, OnTimerComplete);
      }
                 
     void OnTimerComplete()
     {
         // Will this timer loop end up creating garbage?
         _timer.StartTimer(5, OnTimerComplete);
     }
 }

Answer 1

Fun! Here is your issue:

 _timer.StartTimer(5, OnTimerComplete);

This seems to be inlined to be:

 _timer.StartTimer(5, () => OnTimerComplete);

Therefore this is creating a new delegate each time you start the timer. If you cache the delegate this is solved:

 public class OtherClass : MonoBehaviour
 {
       private Timer _timer;
       private Action _action;
 
       void Start()
       {
           _timer = gameObject.AddComponent<Timer>();
          _action = OnTimerComplete;
           _timer.StartTimer(5, _action);
       }
                  
      void OnTimerComplete()
      {
          // Will this timer loop end up creating garbage?
          _timer.StartTimer(5, _action);
      }
  }

Hope this helps!

For reference, here is my test:

 using System;
 using UnityEngine;
 
 public class ActionDelegateGarbageTest : MonoBehaviour
 {
     private Action mAction;
 
     public void Start ()
     {
         mAction = () => EventReciever ();
     }
 
     public void Update ()
     {
         //doesn't create garbage
         //PassTest (mAction);
 
         //creates garbage
         //PassTest (EventReciever);
     }
 
     private void PassTest (Action actionToComplete)
     {
         actionToComplete();
     }
 
     private void EventReciever()
     {
         
     }
 }

Does passing an Action as a parameter create garbage?

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