NetworkManager forces `Application.runInBackground` globally even when networking is inactive

[Pattrigue]

General
Unity version: 6.1.15
Fish-Networking version: 4.6.12R
Discord link: I did not troubleshoot this on Discord, as it is an apparent flaw with the way this was implemented.

Description
The NetworkManager has a _runInBackground property which, when enabled, unconditionally sets Application.runInBackground in Awake and again in the TimeManager_OnLateUpdate callback.

This means the application will always run in the background whenever NetworkManager exists in the scene, even if no client or server is active.

For games where multiplayer is optional (e.g., mostly singleplayer with occasional online sessions), this is undesirable.

The documentation itself states:

Running in the background is often essential for clients, and especially for the server.

This suggests it should only be enforced while networking is active, not globally.

Replication
Steps to reproduce the behavior:
Just run your game with a NetworkManager whose "Run in background" property is set to true.

Expected behavior

• The _runInBackground property should only affect Application.runInBackground while a network session (server or client) is active.
• When networking is inactive, Unity’s project-level setting should be respected.

[FirstGearGames]

This seems more like an enhancement given some may want the app to still run in the background even w/o a connection.

I think it's safe to say we can put in a toggle to only enable when socket is active though.

[Pattrigue]

Agreed! This would be a great addition.

[FirstGearGames]

Added in 4.6.16R

Entirely in the NetworkManager.cs add the following.

        #region Private.
        /// <summary>
        /// Value of Application.RunInBackground before starting any network connection.
        /// </summary>
        /// <remarks>A null value indicates not yet set.</remarks>
        private bool? _offlineApplicationRunInBackground;
        #endregion

        /// <summary>
        /// Updates Application.RunInBackground to NetworkManager setting when connected, and application setting when not connected.
        /// </summary>
        private void UpdateRunInBackgroundIfApplicable()
        {
            // Not configured to update values.
            if (!_runInBackground)
                return;

            bool anythingStarted = ServerManager.IsAnyServerStarted() || ClientManager.Started;

            // Check to set values.
            if (anythingStarted)
            {
                // Already set.
                if (_offlineApplicationRunInBackground != null)
                    return;
                
                //Update run in background after caching current value.
                _offlineApplicationRunInBackground = Application.runInBackground;
                Application.runInBackground = true;
            }
            else
            {
                // Already unset.
                if (_offlineApplicationRunInBackground == null)
                    return;
                
                //Update run in background then unset cached value.
                Application.runInBackground = _offlineApplicationRunInBackground.Value;
                _offlineApplicationRunInBackground = null;
            }
        }

In method private void InitializeComponents() make the following changes by subscribing to events, where ClientManager and ServerManager are initialized.

            /* There is no need to unsubscribe to either of the connection
             * state events below since components
             * will be destroyed with the NetworkManager. */
            
            ClientManager.InitializeOnce_Internal(this);
            ClientManager.OnClientConnectionState+= ClientManager_OnClientConnectionState;
            
            ServerManager.InitializeOnce_Internal(this);
            ServerManager.OnServerConnectionState += ServerManager_OnServerConnectionState;

As well delete this method and anything calling it.

   private void SetRunInBackground()
        {
            Application.runInBackground = _runInBackground;
        }

It will probably be a good idea to only set run in background when using an online transport -- will see how difficult it is to make this change.