Diagnostics: Adds total number of active clients information

Microsoft.Azure.Cosmos/src/CosmosClient.cs

@@ -100,8 +100,11 @@ public class CosmosClient : IDisposable
         private readonly string DatabaseRootUri = Paths.Databases_Root;
         private ConsistencyLevel? accountConsistencyLevel;
         private bool isDisposed = false;
+        private object disposedLock = new object();
 
         internal static int numberOfClientsCreated;
+        internal static int NumberOfActiveClients;
+
         internal DateTime? DisposedDateTimeUtc { get; private set; } = null;
 
         static CosmosClient()
@@ -262,6 +265,7 @@ internal CosmosClient(
             clientOptions ??= new CosmosClientOptions();
 
             this.ClientId = this.IncrementNumberOfClientsCreated();
+
             this.ClientContext = ClientContextCore.Create(
                 this,
                 clientOptions);
@@ -1232,9 +1236,27 @@ private Task InitializeContainersAsync(IReadOnlyList<(string databaseId, string
 
         private int IncrementNumberOfClientsCreated()
         {
+            this.IncrementNumberOfActiveClients();
+
             return Interlocked.Increment(ref numberOfClientsCreated);
         }
 
+        private int IncrementNumberOfActiveClients()
+        {
+            return Interlocked.Increment(ref NumberOfActiveClients);
+        }
+
+        private int DecrementNumberOfActiveClients()
+        {
+            // In case dispose is called multiple times. Check if at least 1 active client is there
+            if (NumberOfActiveClients > 0)
+            {
+                return Interlocked.Decrement(ref NumberOfActiveClients);
+            }
+
+            return 0;
+        }
+
         private async Task InitializeContainerAsync(string databaseId, string containerId, CancellationToken cancellationToken = default)
         {
             ContainerInternal container = (ContainerInternal)this.GetContainer(databaseId, containerId);
@@ -1280,17 +1302,22 @@ public void Dispose()
         /// <param name="disposing">True if disposing</param>
         protected virtual void Dispose(bool disposing)
         {
-            if (!this.isDisposed)
+            lock (this.disposedLock)
             {
-                this.DisposedDateTimeUtc = DateTime.UtcNow;
-
-                if (disposing)
+                if (this.isDisposed == true)
                 {
-                    this.ClientContext.Dispose();
+                    return;
                 }
-
                 this.isDisposed = true;
             }
+
+            this.DisposedDateTimeUtc = DateTime.UtcNow;
+
+            if (disposing)
+            {
+                this.ClientContext.Dispose();
+                this.DecrementNumberOfActiveClients();
+            }   
         }
     }
 }

Microsoft.Azure.Cosmos/src/Tracing/TraceData/ClientConfigurationTraceDatum.cs

@@ -28,6 +28,7 @@ public ClientConfigurationTraceDatum(CosmosClientContext cosmosClientContext, Da
                                                     cosmosClientContext.ClientOptions.ApplicationPreferredRegions);
 
             this.cachedNumberOfClientCreated = CosmosClient.numberOfClientsCreated;
+            this.cachedNumberOfActiveClient = CosmosClient.NumberOfActiveClients;
             this.cachedUserAgentString = this.UserAgentContainer.UserAgent;
             this.cachedSerializedJson = this.GetSerializedDatum();
         }
@@ -46,9 +47,11 @@ public ReadOnlyMemory<byte> SerializedJson
         {
             get
             {
-                if ((this.cachedUserAgentString != this.UserAgentContainer.UserAgent) ||
-                    (this.cachedNumberOfClientCreated != CosmosClient.numberOfClientsCreated))
+                if (this.cachedUserAgentString != this.UserAgentContainer.UserAgent ||
+                    this.cachedNumberOfClientCreated != CosmosClient.numberOfClientsCreated ||
+                    this.cachedNumberOfActiveClient != CosmosClient.NumberOfActiveClients)
                 {
+                    this.cachedNumberOfActiveClient = CosmosClient.NumberOfActiveClients;
                     this.cachedNumberOfClientCreated = CosmosClient.numberOfClientsCreated;
                     this.cachedUserAgentString = this.UserAgentContainer.UserAgent;
                     this.cachedSerializedJson = this.GetSerializedDatum();
@@ -62,6 +65,8 @@ public ReadOnlyMemory<byte> SerializedJson
 
         private ReadOnlyMemory<byte> cachedSerializedJson;
         private int cachedNumberOfClientCreated;
+        private int cachedNumberOfActiveClient;
+
         private string cachedUserAgentString;
 
         internal override void Accept(ITraceDatumVisitor traceDatumVisitor)
@@ -79,6 +84,8 @@ private ReadOnlyMemory<byte> GetSerializedDatum()
 
             jsonTextWriter.WriteFieldName("NumberOfClientsCreated");
             jsonTextWriter.WriteNumber64Value(this.cachedNumberOfClientCreated);
+            jsonTextWriter.WriteFieldName("NumberOfActiveClients");
+            jsonTextWriter.WriteNumber64Value(this.cachedNumberOfActiveClient);
             jsonTextWriter.WriteFieldName("User Agent");
             jsonTextWriter.WriteStringValue(this.cachedUserAgentString);
 

Microsoft.Azure.Cosmos/src/Tracing/TraceWriter.TraceTextWriter.cs

@@ -479,6 +479,7 @@ public void Visit(ClientConfigurationTraceDatum clientConfigurationTraceDatum)
                     stringBuilder.AppendLine("Client Configuration");
                     stringBuilder.AppendLine($"Client Created Time: {clientConfigurationTraceDatum.ClientCreatedDateTimeUtc.ToString("o", CultureInfo.InvariantCulture)}");
                     stringBuilder.AppendLine($"Number Of Clients Created: {CosmosClient.numberOfClientsCreated}");
+                    stringBuilder.AppendLine($"Number Of Active Clients: {CosmosClient.NumberOfActiveClients}");
                     stringBuilder.AppendLine($"User Agent: {clientConfigurationTraceDatum.UserAgentContainer.UserAgent}");
                     stringBuilder.AppendLine("Connection Config:");
                     stringBuilder.AppendLine($"{space}'gw': {clientConfigurationTraceDatum.GatewayConnectionConfig}");

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/ActiveClientDiagnosticTest.cs

@@ -0,0 +1,71 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+
+namespace Microsoft.Azure.Cosmos.Tests
+{
+    using System;
+    using System.Threading.Tasks;
+    using System.Xml.Serialization;
+    using VisualStudio.TestTools.UnitTesting;
+
+    [TestClass]
+    public class ActiveClientDiagnosticTest
+    {
+        private const string ConnectionString = "AccountEndpoint=https://localtestcosmos.documents.azure.com:443/;AccountKey=425Mcv8CXQqzRNCgFNjIhT424GK99CKJvASowTnq15Vt8LeahXTcN5wt3342vQ==;";
+
+        [TestInitialize]
+        public void Initialize()
+        {
+            CosmosClient.NumberOfActiveClients = 0;
+        }
+
+        [TestMethod]
+        public void SingleClientTest()
+        {
+            CosmosClient cosmosClient = new CosmosClient(ConnectionString);
+            Assert.AreEqual(1, CosmosClient.NumberOfActiveClients);
+            cosmosClient.Dispose();
+        }
+
+        [TestMethod]
+        public void MultiClientTest()
+        {
+            CosmosClient cosmosClient1 = new CosmosClient(ConnectionString); // Initializing 1st time
+            CosmosClient cosmosClient2 = new CosmosClient(ConnectionString); // Initializing 2nd time
+            Assert.AreEqual(2, CosmosClient.NumberOfActiveClients);
+            cosmosClient1.Dispose();
+            cosmosClient2.Dispose();
+        }
+
+        [TestMethod]
+        public void MultiClientWithDisposeTest()
+        {
+            CosmosClient cosmosClient1 = new CosmosClient(ConnectionString); // Initializing 1st time
+            CosmosClient cosmosClient2 = new CosmosClient(ConnectionString); // Initializing 2nd time
+            CosmosClient cosmosClient3 = new CosmosClient(ConnectionString); // Initializing 3rd time
+            cosmosClient2.Dispose(); // Destroying 1 instance
+            Assert.AreEqual(2, CosmosClient.NumberOfActiveClients);
+            cosmosClient1.Dispose();
+            cosmosClient3.Dispose();
+        }
+
+        [TestMethod]
+        public void MultiThreadClientDisposeTest()
+        {
+            CosmosClient cosmosClient1 = new CosmosClient(ConnectionString); // Initializing 1st time
+            CosmosClient cosmosClient2 = new CosmosClient(ConnectionString);
+
+            Parallel.Invoke(cosmosClient2.Dispose, 
+                cosmosClient2.Dispose, 
+                cosmosClient2.Dispose, 
+                cosmosClient2.Dispose, 
+                cosmosClient2.Dispose);
+
+            // Initializing 2nd time
+            Assert.AreEqual(1, CosmosClient.NumberOfActiveClients);
+            cosmosClient1.Dispose();
+            cosmosClient2.Dispose();
+        }
+    }
+}

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/DefaultTracingTests.cs

@@ -19,8 +19,9 @@ public class DefaultTracingTests
         [TestMethod]
         public void DefaultTracingEnableTest()
         {
-            // Access cosmos client to cause the static consturctor to get called
+            // Access cosmos client to cause the static constructor to get called
             Assert.IsTrue(CosmosClient.numberOfClientsCreated >= 0);
+            Assert.IsTrue(CosmosClient.NumberOfActiveClients >= 0);
 
             if (!Debugger.IsAttached)
             {