From 7bd0fdaf19ff4110f34c74dbc8aa83864e19bd32 Mon Sep 17 00:00:00 2001
From: Eric Garnier <Eric_Garnier@hotmail.com>
Date: Sat, 19 Dec 2020 17:48:42 +0100
Subject: [PATCH 1/2] fix for issue 71

---
 CryptoExchange.Net/Sockets/SocketConnection.cs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/CryptoExchange.Net/Sockets/SocketConnection.cs b/CryptoExchange.Net/Sockets/SocketConnection.cs
index 5d30915..625e7a2 100644
--- a/CryptoExchange.Net/Sockets/SocketConnection.cs
+++ b/CryptoExchange.Net/Sockets/SocketConnection.cs
@@ -153,6 +153,10 @@ namespace CryptoExchange.Net.Sockets
                 if (pendingRequest.Check(tokenData))
                 {
                     pendingRequests.Remove(pendingRequest);
+                    if (pendingRequest.Result == null)
+					{
+                        continue; // A previous timeout.
+					}
                     if (!socketClient.ContinueOnQueryResponse)
                         return;
                     handledResponse = true;

From 0db71a3fb6713b1d27fd47ab9d51737d33f46b82 Mon Sep 17 00:00:00 2001
From: Eric Garnier <Eric_Garnier@hotmail.com>
Date: Sun, 20 Dec 2020 10:59:38 +0100
Subject: [PATCH 2/2] Protect pendingRequest list from concurrent access.

---
 CryptoExchange.Net/Sockets/SocketConnection.cs | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/CryptoExchange.Net/Sockets/SocketConnection.cs b/CryptoExchange.Net/Sockets/SocketConnection.cs
index 625e7a2..d064b6a 100644
--- a/CryptoExchange.Net/Sockets/SocketConnection.cs
+++ b/CryptoExchange.Net/Sockets/SocketConnection.cs
@@ -148,11 +148,19 @@ namespace CryptoExchange.Net.Sockets
             }
 
             var handledResponse = false;
-            foreach (var pendingRequest in pendingRequests.ToList())
+            PendingRequest[] requests;
+            lock(pendingRequests)
+			{
+                requests = pendingRequests.ToArray();
+			}
+            foreach (var pendingRequest in requests)
             {
                 if (pendingRequest.Check(tokenData))
                 {
-                    pendingRequests.Remove(pendingRequest);
+                    lock (pendingRequests)
+                    {
+                        pendingRequests.Remove(pendingRequest);
+                    }
                     if (pendingRequest.Result == null)
 					{
                         continue; // A previous timeout.
@@ -237,7 +245,10 @@ namespace CryptoExchange.Net.Sockets
         public virtual Task SendAndWait<T>(T obj, TimeSpan timeout, Func<JToken, bool> handler)
         {
             var pending = new PendingRequest(handler, timeout);
-            pendingRequests.Add(pending);
+            lock (pendingRequests)
+            {
+                pendingRequests.Add(pending);
+            }
             Send(obj);
             return pending.Event.WaitOneAsync(timeout);
         }