Do not start language worker process if in-proc (#10161)

Author: liliankasem

release_notes.md

@@ -13,4 +13,5 @@
 - Update PowerShell worker 7.2 to [4.0.3220](https://github.com/Azure/azure-functions-powershell-worker/releases/tag/v4.0.3220)
 - Update PowerShell worker 7.4 to [4.0.3219](https://github.com/Azure/azure-functions-powershell-worker/releases/tag/v4.0.3219)
 - Ensuring proxies are disabled, with a warning, when running in Flex Consumption. 
-- Fixed an issue leading to a race when invocation responses returned prior to HTTP requests being sent in proxied scenarios.
+- Fixed an issue leading to a race when invocation responses returned prior to HTTP requests being sent in proxied scenarios.
+- Language worker channels will not be started during placeholder mode if we are in-process (#10161)

src/WebJobs.Script/Environment/EnvironmentExtensions.cs

@@ -614,13 +614,25 @@ public static HashSet<string> GetLanguageWorkerListToStartInPlaceholder(this IEn
             string placeholderList = environment.GetEnvironmentVariableOrDefault(RpcWorkerConstants.FunctionWorkerPlaceholderModeListSettingName, string.Empty);
             var placeholderRuntimeSet = new HashSet<string>(placeholderList.Trim().Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries).Select(p => p.Trim()));
             string workerRuntime = environment.GetEnvironmentVariable(RpcWorkerConstants.FunctionWorkerRuntimeSettingName);
-            if (!string.IsNullOrEmpty(workerRuntime))
+
+            if (!environment.IsInProc(workerRuntime))
             {
                 placeholderRuntimeSet.Add(workerRuntime);
             }
+
             return placeholderRuntimeSet;
         }
 
+        public static bool IsInProc(this IEnvironment environment, string workerRuntime = null)
+        {
+            if (workerRuntime is null)
+            {
+                workerRuntime = environment.GetEnvironmentVariable(RpcWorkerConstants.FunctionWorkerRuntimeSettingName);
+            }
+
+            return string.IsNullOrEmpty(workerRuntime) || string.Equals(workerRuntime, RpcWorkerConstants.DotNetLanguageWorkerName, StringComparison.OrdinalIgnoreCase);
+        }
+
         public static bool IsApplicationInsightsAgentEnabled(this IEnvironment environment)
         {
             // cache the value of the environment variable

test/WebJobs.Script.Tests/Extensions/EnvironmentExtensionsTests.cs

@@ -454,5 +454,37 @@ public void AzureFilesAppSettingsExist_ReturnsExpectedResult(string connectionSt
             environment.SetEnvironmentVariable(AzureFilesContentShare, contentShare);
             Assert.Equal(expected, environment.AzureFilesAppSettingsExist());
         }
+
+        [Theory]
+        [InlineData(null, true)]
+        [InlineData("", true)]
+        [InlineData("dotnet", true)]
+        [InlineData("dotnet-isolated", false)]
+        [InlineData("java", false)]
+        [InlineData("python", false)]
+        [InlineData("node", false)]
+        public void IsInProc_ReturnsExpectedResult(string value, bool expected)
+        {
+            var environment = new TestEnvironment();
+            if (value != null)
+            {
+                environment.SetEnvironmentVariable(FunctionWorkerRuntime, value);
+            }
+            Assert.Equal(expected, environment.IsInProc());
+        }
+
+        [Theory]
+        [InlineData(null, true)]
+        [InlineData("", true)]
+        [InlineData("dotnet", true)]
+        [InlineData("dotnet-isolated", false)]
+        [InlineData("java", false)]
+        [InlineData("python", false)]
+        [InlineData("node", false)]
+        public void IsInProc_WithRuntimeParameter_ReturnsExpectedResult(string value, bool expected)
+        {
+            var environment = new TestEnvironment();
+            Assert.Equal(expected, environment.IsInProc(value));
+        }
     }
 }