Tweak that when the EnablePublishParallelSend option is true, it wi…

…ll be put task into the .NET thread pool in batches rather than all at once. (#1540)

src/DotNetCore.CAP/Processor/IDispatcher.Default.cs

@@ -18,7 +18,6 @@ namespace DotNetCore.CAP.Processor;
 
 public class Dispatcher : IDispatcher
 {
-    private CancellationTokenSource? _tasksCts;
     private readonly CancellationTokenSource _delayCts = new();
     private readonly ISubscribeExecutor _executor;
     private readonly ILogger<Dispatcher> _logger;
@@ -28,16 +27,15 @@ public class Dispatcher : IDispatcher
     private readonly PriorityQueue<MediumMessage, long> _schedulerQueue;
     private readonly bool _enableParallelExecute;
     private readonly bool _enableParallelSend;
+    private readonly int _pChannelSize;
 
+    private CancellationTokenSource? _tasksCts;
     private Channel<MediumMessage> _publishedChannel = default!;
     private Channel<(MediumMessage, ConsumerExecutorDescriptor?)> _receivedChannel = default!;
     private long _nextSendTime = DateTime.MaxValue.Ticks;
 
-    public Dispatcher(ILogger<Dispatcher> logger,
-        IMessageSender sender,
-        IOptions<CapOptions> options,
-        ISubscribeExecutor executor,
-        IDataStorage storage)
+    public Dispatcher(ILogger<Dispatcher> logger, IMessageSender sender, IOptions<CapOptions> options,
+        ISubscribeExecutor executor, IDataStorage storage)
     {
         _logger = logger;
         _sender = sender;
@@ -47,6 +45,7 @@ public Dispatcher(ILogger<Dispatcher> logger,
         _storage = storage;
         _enableParallelExecute = options.Value.EnableSubscriberParallelExecute;
         _enableParallelSend = options.Value.EnablePublishParallelSend;
+        _pChannelSize = Environment.ProcessorCount * 500;
     }
 
     public async Task Start(CancellationToken stoppingToken)
@@ -55,14 +54,13 @@ public async Task Start(CancellationToken stoppingToken)
         _tasksCts = CancellationTokenSource.CreateLinkedTokenSource(stoppingToken, CancellationToken.None);
         _tasksCts.Token.Register(() => _delayCts.Cancel());
 
-        _publishedChannel = Channel.CreateBounded<MediumMessage>(
-            new BoundedChannelOptions(5000)
-            {
-                AllowSynchronousContinuations = true,
-                SingleReader = true,
-                SingleWriter = true,
-                FullMode = BoundedChannelFullMode.Wait
-            });
+        _publishedChannel = Channel.CreateBounded<MediumMessage>(new BoundedChannelOptions(_pChannelSize)
+        {
+            AllowSynchronousContinuations = true,
+            SingleReader = true,
+            SingleWriter = true,
+            FullMode = BoundedChannelFullMode.Wait
+        });
 
         await Task.Run(Sending, _tasksCts.Token).ConfigureAwait(false); //here return valuetask
 
@@ -207,28 +205,45 @@ private async ValueTask Sending()
         try
         {
             while (await _publishedChannel.Reader.WaitToReadAsync(_tasksCts!.Token).ConfigureAwait(false))
-                while (_publishedChannel.Reader.TryRead(out var message))
-                    try
+            {
+                if (_enableParallelSend)
+                {
+                    var tasks = new List<Task>();
+                    var batchSize = _pChannelSize / 50;
+                    for (var i = 0; i < batchSize && _publishedChannel.Reader.TryRead(out var message); i++)
                     {
                         var item = message;
-                        if (_enableParallelSend)
+                        tasks.Add(Task.Run(async () =>
                         {
-                            _ = Task.Run(async () =>
+                            try
                             {
                                 var result = await _sender.SendAsync(item).ConfigureAwait(false);
                                 if (!result.Succeeded) _logger.MessagePublishException(item.Origin.GetId(), result.ToString(), result.Exception);
-                            });
+                            }
+                            catch (Exception ex)
+                            {
+                                _logger.LogError(ex, $"An exception occurred when sending a message to the transport. Id:{message.DbId}");
+                            }
+                        }));
+                    }
+
+                    await Task.WhenAll(tasks);
+                }
+                else
+                {
+                    while (_publishedChannel.Reader.TryRead(out var message))
+                        try
+                        {
+                            var result = await _sender.SendAsync(message).ConfigureAwait(false);
+                            if (!result.Succeeded) _logger.MessagePublishException(message.Origin.GetId(), result.ToString(), result.Exception);
                         }
-                        else
+                        catch (Exception ex)
                         {
-                            var result = await _sender.SendAsync(item).ConfigureAwait(false);
-                            if (!result.Succeeded) _logger.MessagePublishException(item.Origin.GetId(), result.ToString(), result.Exception);
+                            _logger.LogError(ex, $"An exception occurred when sending a message to the transport. Id:{message.DbId}");
                         }
-                    }
-                    catch (Exception ex)
-                    {
-                        _logger.LogError(ex, "An exception occurred when sending a message to the transport. Id:{MessageId}", message.DbId);
-                    }
+                }
+            }
+
         }
         catch (OperationCanceledException)
         {