fix: refine polling and settings layout

src/LiveRecorder.Infrastructure/Services/LiveRoomPollingBackgroundService.cs

@@ -24,6 +24,8 @@ public sealed class LiveRoomPollingBackgroundService : BackgroundService
     private static readonly TimeSpan OfflineGracefulStopTimeout = TimeSpan.FromSeconds(20);
     private static readonly TimeSpan OfflineForcedStopTimeout = TimeSpan.FromSeconds(8);
     private static readonly TimeSpan ExceptionEmailCooldown = TimeSpan.FromHours(6);
+    private static readonly TimeSpan PollDispatchSpacing = TimeSpan.FromMilliseconds(400);
+    private const int MaxConcurrentLiveRoomPolls = 2;
 
     private readonly IServiceScopeFactory _serviceScopeFactory;
     private readonly ILogger<LiveRoomPollingBackgroundService> _logger;
@@ -73,15 +75,7 @@ public sealed class LiveRoomPollingBackgroundService : BackgroundService
                     .Select(static item => item.Id)
                     .ToList();
 
-                foreach (var liveRoomId in liveRoomIds)
-                {
-                    if (stoppingToken.IsCancellationRequested)
-                    {
-                        break;
-                    }
-
-                    await PollLiveRoomAsync(liveRoomId, settings, stoppingToken);
-                }
+                await PollLiveRoomsAsync(liveRoomIds, settings, stoppingToken);
             }
             catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
             {
@@ -130,6 +124,52 @@ public sealed class LiveRoomPollingBackgroundService : BackgroundService
     private static Task DelayAsync(int delaySeconds, CancellationToken cancellationToken) =>
         Task.Delay(TimeSpan.FromSeconds(Math.Clamp(delaySeconds, 10, 3600)), cancellationToken);
 
+    private async Task PollLiveRoomsAsync(
+        IReadOnlyList<Guid> liveRoomIds,
+        SystemSettingsDto settings,
+        CancellationToken cancellationToken)
+    {
+        if (liveRoomIds.Count == 0)
+        {
+            return;
+        }
+
+        using var semaphore = new SemaphoreSlim(Math.Min(MaxConcurrentLiveRoomPolls, liveRoomIds.Count));
+        var tasks = new List<Task>(liveRoomIds.Count);
+
+        for (var index = 0; index < liveRoomIds.Count; index++)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+
+            await semaphore.WaitAsync(cancellationToken);
+            var liveRoomId = liveRoomIds[index];
+            tasks.Add(PollLiveRoomWithReleaseAsync(liveRoomId, settings, semaphore, cancellationToken));
+
+            if (index < liveRoomIds.Count - 1)
+            {
+                await Task.Delay(PollDispatchSpacing, cancellationToken);
+            }
+        }
+
+        await Task.WhenAll(tasks);
+    }
+
+    private async Task PollLiveRoomWithReleaseAsync(
+        Guid liveRoomId,
+        SystemSettingsDto settings,
+        SemaphoreSlim semaphore,
+        CancellationToken cancellationToken)
+    {
+        try
+        {
+            await PollLiveRoomAsync(liveRoomId, settings, cancellationToken);
+        }
+        finally
+        {
+            semaphore.Release();
+        }
+    }
+
     private async Task PollLiveRoomAsync(Guid liveRoomId, SystemSettingsDto settings, CancellationToken cancellationToken)
     {
         using var scope = _serviceScopeFactory.CreateScope();