Queue.Enqueue and IndexOutOfRangeException

Hong 1,211

I have been chasing a strange occasional IndexOutOfRangeException for a while and pinned it on the following line:

myQueue.Enqueue(myObject)

where:

protected Queue<MyObject> myQueue{ get; set; }

I don't know how this is possible. The stack trace:

System.IndexOutOfRangeException: Index was outside the bounds of the array.
 Stack Trace:
   at Internal.Runtime.CompilerHelpers.ThrowHelpers.ThrowIndexOutOfRangeException() + 0x25
   at ClassLibraryFoo.NVT.DecoderWin.<MethodFoo>d__38.MoveNext() + 0x46f

Could anyone shed some light on this?

Viorel 118.2K Reputation points

2024-06-12T09:55:53.1033333+00:00

The stack seems to be related to an issue with DecoderWin.

Maybe you are using parallel threads incorrectly.
Hong 1,211 Reputation points

2024-06-12T11:12:10.0433333+00:00

Thank you, Viorel. Yes, myQueue is accessed by multiple threads. Did you mean that this is a threading issue, not related to the index or size of myQueue?
Hong 1,211 Reputation points

2024-06-12T13:51:44.3633333+00:00

Thank you for the tip. I will definitely give Queue.Synchronized a shot. I used ConcurentQueue for many years until recently and changed it to Queue because I suspected ConcurentQueue was leaking memory as reported by some others.
Hong 1,211 Reputation points

2024-06-13T18:03:21.42+00:00
Now, I have further indisputable proof that myQueue.Enqueue(myObject) throws the IndexOutOfRangeException with the following code to catch the exception:

try { myQueue.Enqueue(myObject); } catch (Exception ex) { //log }

I will try Queue.Synchronized(myQueue) to see if it fixes it.
Junjie Zhu - MSFT 18,736 Reputation points Microsoft Vendor

2024-06-18T08:42:02.7366667+00:00

Hi @Hong ,

Haven't heard from you for a while. can Queue.Synchronized(myQueue) fix the problem?
Hong 1,211 Reputation points

2024-06-19T01:36:56.15+00:00

@Junjie Zhu - MSFT I released an update with the use of Queue.Synchronized(myQueue) yesterday. I have not seen the IndexOutOfRangeException from this update, so I assume it has fixed the problem. The comment from Viorel can be turned into the answer.
Junjie Zhu - MSFT 18,736 Reputation points Microsoft Vendor

2024-06-20T09:58:50.28+00:00

Hi @Hong ,

Glad to hear that, I turned the correct solution into an answer, to help more people who encounter the same problem, If the answer is the right solution, please click "Accept Answer" and kindly upvote it.

Accepted answer

Viorel 118.2K Reputation points

2024-06-12T11:53:37.8433333+00:00
I think that the exception is caused by threading issues.

Maybe you can use a mutex, or a ConcurentQueue, or a queue returned by Queue.Synchronized(myQueue).

Also see the remark about the enumerators:

https://learn.microsoft.com/en-us/dotnet/api/system.collections.queue#thread-safety
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