From c7890aaadb13fb63274dbc630172e92bfbee2cd6 Mon Sep 17 00:00:00 2001
From: "Namhyeon, Go" <gnh1201@catswords.re.kr>
Date: Tue, 28 Oct 2025 14:12:25 +0900
Subject: [PATCH] Serialize connection creation per key

---
 .../ConnectionManagerBase.cs                  | 27 ++++++++++++++++---
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
index 9bf436f..d2129f5 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
@@ -22,6 +22,8 @@ namespace WelsonJS.Launcher
     {
         private readonly ConcurrentDictionary<string, (TConnection Connection, TParameters Parameters)> _pool
             = new ConcurrentDictionary<string, (TConnection, TParameters)>();
+        private readonly ConcurrentDictionary<string, SemaphoreSlim> _openLocks
+            = new ConcurrentDictionary<string, SemaphoreSlim>();
 
         /// <summary>
         /// Creates a unique cache key for the given connection parameters.
@@ -61,11 +63,28 @@ namespace WelsonJS.Launcher
                 return existing.Connection;
             }
 
-            RemoveInternal(key, existing.Connection);
+            var gate = _openLocks.GetOrAdd(key, _ => new SemaphoreSlim(1, 1));
+            await gate.WaitAsync(token).ConfigureAwait(false);
+            try
+            {
+                if (_pool.TryGetValue(key, out existing) && IsConnectionHealthy(existing.Connection))
+                {
+                    return existing.Connection;
+                }
 
-            var connection = await OpenConnectionAsync(parameters, token).ConfigureAwait(false);
-            _pool[key] = (connection, parameters);
-            return connection;
+                if (existing.Connection != null && !IsConnectionHealthy(existing.Connection))
+                {
+                    RemoveInternal(key, existing.Connection);
+                }
+
+                var connection = await OpenConnectionAsync(parameters, token).ConfigureAwait(false);
+                _pool[key] = (connection, parameters);
+                return connection;
+            }
+            finally
+            {
+                gate.Release();
+            }
         }
 
         /// <summary>