From 5fdeb42ec0b51a3c3a7e1003e1a9a4ef175bb4fb Mon Sep 17 00:00:00 2001
From: Surayya Huseyn Zada <shuseynzada@microsoft.com>
Date: Thu, 30 Oct 2025 12:24:14 +0100
Subject: [PATCH] fix race condition in NodeProvideOutOfProcTaskHost

---
 .../Communications/NodeProviderOutOfProcTaskHost.cs  | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/Build/BackEnd/Components/Communications/NodeProviderOutOfProcTaskHost.cs b/src/Build/BackEnd/Components/Communications/NodeProviderOutOfProcTaskHost.cs
index b93889a94b5..aae3bd342ab 100644
--- a/src/Build/BackEnd/Components/Communications/NodeProviderOutOfProcTaskHost.cs
+++ b/src/Build/BackEnd/Components/Communications/NodeProviderOutOfProcTaskHost.cs
@@ -86,12 +86,12 @@ internal class NodeProviderOutOfProcTaskHost : NodeProviderOutOfProcBase, INodeP
         /// <summary>
         /// A mapping of all of the INodePacketFactories wrapped by this provider.
         /// </summary>
-        private IDictionary<int, INodePacketFactory> _nodeIdToPacketFactory;
+        private ConcurrentDictionary<int, INodePacketFactory> _nodeIdToPacketFactory;
 
         /// <summary>
         /// A mapping of all of the INodePacketHandlers wrapped by this provider.
         /// </summary>
-        private IDictionary<int, INodePacketHandler> _nodeIdToPacketHandler;
+        private ConcurrentDictionary<int, INodePacketHandler> _nodeIdToPacketHandler;
 
         /// <summary>
         /// Keeps track of the set of nodes for which we have not yet received shutdown notification.
@@ -207,8 +207,8 @@ public void InitializeComponent(IBuildComponentHost host)
         {
             this.ComponentHost = host;
             _nodeContexts = new ConcurrentDictionary<int, NodeContext>();
-            _nodeIdToPacketFactory = new Dictionary<int, INodePacketFactory>();
-            _nodeIdToPacketHandler = new Dictionary<int, INodePacketHandler>();
+            _nodeIdToPacketFactory = new ConcurrentDictionary<int, INodePacketFactory>();
+            _nodeIdToPacketHandler = new ConcurrentDictionary<int, INodePacketHandler>();
             _activeNodes = new HashSet<int>();
 
             _noNodesActiveEvent = new ManualResetEvent(true);
@@ -606,8 +606,8 @@ internal void DisconnectFromHost(int nodeId)
         {
             ErrorUtilities.VerifyThrow(_nodeIdToPacketFactory.ContainsKey(nodeId) && _nodeIdToPacketHandler.ContainsKey(nodeId), "Why are we trying to disconnect from a context that we already disconnected from?  Did we call DisconnectFromHost twice?");
 
-            _nodeIdToPacketFactory.Remove(nodeId);
-            _nodeIdToPacketHandler.Remove(nodeId);
+            _nodeIdToPacketFactory.TryRemove(nodeId, out _);
+            _nodeIdToPacketHandler.TryRemove(nodeId, out _);
         }
 
         /// <summary>