Buffer defaults avoiding LOH (#383)

* Buffer defaults avoiding LOH

* MinSegmentSize to 64K

* MinSegmentSize to 16K

* Update src/NATS.Client.Core/Commands/CommandWriter.cs

Co-authored-by: Caleb Lloyd <2414837+caleblloyd@users.noreply.github.com>

---------

Co-authored-by: Caleb Lloyd <2414837+caleblloyd@users.noreply.github.com>

Author: mtmk

src/NATS.Client.Core/Commands/CommandWriter.cs

@@ -23,8 +23,9 @@ internal sealed class CommandWriter : IAsyncDisposable
     // assuming 40 bytes TCP overhead + 40 bytes TLS overhead per packet
     private const int SendMemSize = 8520;
 
-    // set to a reasonable socket write mem size
-    private const int MinSegmentSize = 65536;
+    // should be more than SendMemSize
+    // https://github.com/nats-io/nats.net.v2/pull/383#discussion_r1484344102
+    private const int MinSegmentSize = 16384;
 
     private readonly ILogger<CommandWriter> _logger;
     private readonly NatsConnection _connection;
@@ -720,6 +721,7 @@ private async ValueTask PongStateMachineAsync(bool lockHeld, CancellationToken c
         }
     }
 
+    [AsyncMethodBuilder(typeof(PoolingAsyncValueTaskMethodBuilder))]
     private async ValueTask PublishStateMachineAsync(bool lockHeld, string subject, string? replyTo, NatsPooledBufferWriter<byte>? headersBuffer, NatsPooledBufferWriter<byte> payloadBuffer, CancellationToken cancellationToken)
     {
         try

src/NATS.Client.Core/NatsOpts.cs

@@ -31,9 +31,9 @@ public sealed record NatsOpts
 
     public ILoggerFactory LoggerFactory { get; init; } = NullLoggerFactory.Instance;
 
-    public int WriterBufferSize { get; init; } = 1048576;
+    public int WriterBufferSize { get; init; } = 65536;
 
-    public int ReaderBufferSize { get; init; } = 1048576;
+    public int ReaderBufferSize { get; init; } = 65536;
 
     public bool UseThreadPoolCallback { get; init; } = false;