Bug Memory leak in NavmeshAgent.SetDestination if multiple agents in the same position

I found out that my game will eventually run out of memory on a dedicated Linux server with 1GB of ram and some SWAP after a few days (can also confirm endless increasing of memory usage on my local Windows machine. Included project that reproduces the issue. Few MBs per minute added).

After using the memory profiler, it seems the problem is in the following wandering AI script: I can confirm that commenting out UserAgent.SetDestination will not make the memory increase.

Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.AI;
3. public class WanderingAI : MonoBehaviour
4. {
5.  
6.     public float wanderRadius;
7.     public float wanderTimer;
8.  
9.     protected Vector3 basePosition;
10.     protected NavMeshAgent agent;
11.     protected float timer;
12.  
13.     void Start()
14.     {
15.         basePosition = gameObject.transform.position;
16.         agent = GetComponent<NavMeshAgent>();
17.         timer = wanderTimer;
18.     }
19.  
20.     // Update is called once per frame
21.     void Update()
22.     {
23.         timer += Time.deltaTime;
24.  
25.         if (timer >= wanderTimer)
26.         {
27.             Vector3 newPos = RandomNavSphere(basePosition, wanderRadius, -1);
28.             agent.SetDestination(newPos); // If this line is disabled. Other native memory (in use / reserved) is not slowly increasing
29.             timer = 0;
30.         }
31.     }
32.  
33.     private Vector3 RandomNavSphere(Vector3 origin, float dist, int layermask)
34.     {
35.         Vector3 randDirection = Random.insideUnitSphere * dist;
36.  
37.         randDirection += origin;
38.  
39.         NavMeshHit navHit;
40.  
41.         NavMesh.SamplePosition(randDirection, out navHit, dist, layermask);
42.  
43.         return navHit.position;
44.     }
45. }

Running this code for a while (few days) will fill up the Other Native Memory. Please see the extreme example in the attachments. its using 8 GB of native memory, while only using around 100MB ram for the rest. This increasing of memory seems to happen if many agents are in one position.

Is this a bug in Unity or in my script? This is tested on the latests LTS release. Included a zip file that reproduces the issue in a clean project

 

Hi @MartinTilo,

I reported a bug. Will try to use your workaround.

using the example in the attachment I let it run for a few minutes and these are the results comparing snapshots:

Not 100% sure where to look at TBH. Its filtered on New and Diff all Native allocations but looks like this only shows the memory region and not if its from NavMesh

 

I did get a case id. Its 1404634. If I receive an issue ID I will post it here @MartinTilo

 

Hi @MartinTilo ,
I did not get an answer yet. Do you know how much time this usually takes?

Also I tried your approach

Code (CSharp):

1. if (timer >= wanderTimer)
2. {
3.     Vector3 newPos = RandomNavSphere(basePosition, wanderRadius, -1);
4.     if (!agent.pathPending) {  
5.       agent.SetDestination(newPos); // If this line is disabled. Other native memory (in use / reserved) is not slowly increasing
6.     }
7.     timer = 0;
8. }

However in the example project it looks like the memory still increases

 

Hi @MartinTilo,

Is there any progress on the ticket? I did not get a reply yet

 

@MartinTilo Thanks for moving this forward. I got a message that this issue is now added to the issue tracker and the QA team successfully reproduced this issue. Its added here https://issuetracker.unity3d.com/is...when-multiple-agents-are-in-the-same-position