Add -y to install.

Project/Assets/ML-Agents/Editor/Tests/StandaloneBuildTest.cs

     {
         const string k_OutputCommandLineFlag = "--mlagents-build-output-path";
         const string k_SceneCommandLineFlag = "--mlagents-build-scene-path";
-        private const string k_BuildTargetFlag = "--mlagents-build-target";
+        const string k_BuildTargetFlag = "--mlagents-build-target";
+        const string k_ScriptingBackendFlag = "--mlagents-scripting-backend";
 
         public static void BuildStandalonePlayerOSX()
         {
             var buildTarget = BuildTarget.StandaloneOSX;
+            var scriptingBackend = ScriptingImplementation.Mono2x;
 
             var args = Environment.GetCommandLineArgs();
             for (var i = 0; i < args.Length - 1; i++)
                 {
                     buildTarget = (BuildTarget)Enum.Parse(typeof(BuildTarget), args[i + 1], ignoreCase: true);
                 }
+                else if (args[i] == k_ScriptingBackendFlag)
+                {
+                    var val = args[i + 1];
+                    if (val == "mono")
+                    {
+                        scriptingBackend = ScriptingImplementation.Mono2x;
+                    }
+                    else
+                    {
+                        scriptingBackend = ScriptingImplementation.IL2CPP;
+                    }
+                }
+            PlayerSettings.SetScriptingBackend(BuildTargetGroup.Standalone, scriptingBackend);
             var buildResult = BuildPipeline.BuildPlayer(
                 scenes,
                 outputPath,

Project/Packages/manifest.json

     "com.unity.modules.physics": "1.0.0",
     "com.unity.modules.physics2d": "1.0.0",
     "com.unity.modules.uielements": "1.0.0",
-    "com.unity.modules.unityanalytics": "1.0.0"
+    "com.unity.modules.unityanalytics": "1.0.0",
+    "com.unity.sysroot.linux-x86_64": "0.1.15-preview",
+    "com.unity.toolchain.win-x86_64-linux-x86_64": "0.1.17-preview",
+    "com.unity.sysroot": "0.1.17-preview"
   },
   "testables": [
     "com.unity.ml-agents",

Project/Packages/packages-lock.json

       "url": "https://packages.unity.com"
     },
     "com.unity.sysroot.linux-x86_64": {
-      "version": "0.1.14-preview",
-      "depth": 1,
+      "version": "0.1.15-preview",
+      "depth": 0,
-        "com.unity.sysroot": "0.1.18-preview"
+        "com.unity.sysroot": "0.1.19-preview"
       },
       "url": "https://packages.unity.com"
     },
       "dependencies": {
         "com.unity.sysroot": "0.1.19-preview",
         "com.unity.sysroot.linux-x86_64": "0.1.14-preview"
+      },
+      "url": "https://packages.unity.com"
+    },
+    "com.unity.toolchain.win-x86_64-linux-x86_64": {
+      "version": "0.1.17-preview",
+      "depth": 0,
+      "source": "registry",
+      "dependencies": {
+        "com.unity.sysroot": "0.1.17-preview",
+        "com.unity.sysroot.linux-x86_64": "0.1.13-preview"
       },
       "url": "https://packages.unity.com"
     },

com.unity.ml-agents/Plugins/ProtoBuffer/runtimes/osx/native/libgrpc_csharp_ext.bundle.meta

   iconMap: {}
   executionOrder: {}
   defineConstraints: []
-  isPreloaded: 0
+  isPreloaded: 1
-      '': Any
+      : Any
     second:
       enabled: 0
       settings:
         Exclude OSXIntel: 0
         Exclude OSXIntel64: 0
         Exclude OSXUniversal: 0
-        Exclude Win: 1
-        Exclude Win64: 1
+        Exclude Win: 0
+        Exclude Win64: 0
-      '': OSXIntel
+      : OSXIntel
-      '': OSXIntel64
+      : OSXIntel64
     second:
       enabled: 1
       settings: {}
     second:
       enabled: 1
       settings:
-        CPU: x86_64
+        CPU: AnyCPU
         DefaultValueInitialized: true
         OS: OSX
   - first:
     second:
       enabled: 0
       settings:
-        CPU: AnyCPU
+        CPU: None
   - first:
       Standalone: LinuxUniversal
     second:
     second:
       enabled: 1
       settings:
-        CPU: AnyCPU
+        CPU: x86_64
-      enabled: 0
+      enabled: 1
-        CPU: AnyCPU
+        CPU: None
-      enabled: 0
+      enabled: 1
-        CPU: AnyCPU
+        CPU: None
   - first:
       iPhone: iOS
     second:

com.unity.ml-agents/Runtime/Communicator/RpcCommunicator.cs

 #define MLA_SUPPORTED_TRAINING_PLATFORM
 #endif
 
-# if MLA_SUPPORTED_TRAINING_PLATFORM
+#if MLA_SUPPORTED_TRAINING_PLATFORM
 using Grpc.Core;
 #if UNITY_EDITOR
 using UnityEditor;
 
         /// The Unity to External client.
         UnityToExternalProto.UnityToExternalProtoClient m_Client;
+        Channel m_Channel;
 
         /// <summary>
         /// Initializes a new instance of the RPCCommunicator class.
                     Debug.Log($"Unexpected exception when trying to initialize communication: {ex}");
                 }
                 initParametersOut = new UnityRLInitParameters();
+                m_Channel.ShutdownAsync().Wait();
                 return false;
             }
 
 
             UpdateEnvironmentWithInput(input.RlInput);
             initParametersOut = initializationInput.RlInitializationInput.ToUnityRLInitParameters();
+            // Be sure to shut down the grpc channel when the application is quitting.
+            Application.quitting += NotifyQuitAndShutDownChannel;
             return true;
 #else
             initParametersOut = new UnityRLInitParameters();
         UnityInputProto Initialize(int port, UnityOutputProto unityOutput, out UnityInputProto unityInput)
         {
             m_IsOpen = true;
-            var channel = new Channel($"localhost:{port}", ChannelCredentials.Insecure);
+            m_Channel = new Channel($"localhost:{port}", ChannelCredentials.Insecure);
-            m_Client = new UnityToExternalProto.UnityToExternalProtoClient(channel);
+            m_Client = new UnityToExternalProto.UnityToExternalProtoClient(m_Channel);
             var result = m_Client.Exchange(WrapMessage(unityOutput, 200));
             var inputMessage = m_Client.Exchange(WrapMessage(null, 200));
             unityInput = inputMessage.UnityInput;
             if (result.Header.Status != 200 || inputMessage.Header.Status != 200)
             {
                 m_IsOpen = false;
-                QuitCommandReceived?.Invoke();
+                NotifyQuitAndShutDownChannel();
+        void NotifyQuitAndShutDownChannel()
+        {
+            QuitCommandReceived?.Invoke();
+            m_Channel.ShutdownAsync().Wait();
+        }
+
 #endregion
 
 #region Destruction
             {
                 case CommandProto.Quit:
                     {
-                        QuitCommandReceived?.Invoke();
+                        NotifyQuitAndShutDownChannel();
                         return;
                     }
                 case CommandProto.Reset:
                 // Not sure if the quit command is actually sent when a
                 // non 200 message is received.  Notify that we are indeed
                 // quitting.
-                QuitCommandReceived?.Invoke();
+                NotifyQuitAndShutDownChannel();
                 return message.UnityInput;
             }
             catch (Exception ex)
                 }
 
                 m_IsOpen = false;
-                QuitCommandReceived?.Invoke();
+                NotifyQuitAndShutDownChannel();
                 return null;
             }
         }

ml-agents/tests/yamato/standalone_build_tests.py

 from .yamato_utils import get_base_path, run_standalone_build
 
 
-def main(scene_path, build_target):
+def main(scene_path, build_target, mlagents_scripting_backend):
     base_path = get_base_path()
     print(f"Running in base path {base_path}")
 
         output_path=executable_name,
         scene_path=scene_path,
         build_target=build_target,
+        scripting_backend=mlagents_scripting_backend,
         log_output_path=None,  # Log to stdout so we get timestamps on the logs
     )
 
     parser.add_argument(
         "--build-target", default="mac", choices=["mac", "linux", "ios", "webgl"]
     )
+    parser.add_argument(
+        "--mlagents-scripting-backend", default="mono", choices=["mono", "il2cpp"]
+    )
-    main(args.scene, args.build_target)
+    main(args.scene, args.build_target, args.mlagents_scripting_backend)

ml-agents/tests/yamato/yamato_utils.py

     output_path: str = None,
     scene_path: str = None,
     build_target: str = None,
+    scripting_backend: str = "mono",
     log_output_path: Optional[str] = f"{get_base_output_path()}/standalone_build.txt",
 ) -> int:
     """
         test_args += ["--mlagents-build-scene-path", scene_path]
     if build_target_enum is not None:
         test_args += ["--mlagents-build-target", build_target_enum]
+    if scripting_backend != "mono":
+        test_args += ["--mlagents-scripting-backend", scripting_backend]
     print(f"{' '.join(test_args)} ...")
 
     timeout = 30 * 60  # 30 minutes, just in case

.yamato/test_versions.metafile

     extra_test: sensor
   - version: 2021.1
     extra_test: llapi
+scripting_backends:
+    - backend: mono
+    - backend: il2cpp

.yamato/training-int-tests.yml

 {% metadata_file .yamato/test_versions.metafile %}
 ---
 {% for editor in test_editors %}
-test_linux_training_int_{{ editor.version }}:
-  name: Test Linux Fast Training {{ editor.version }}
+{% for backend in scripting_backends %}
+test_linux_training_int_{{ editor.version }}_{{ backend.backend }}:
+  name: Test Linux Fast Training {{ editor.version }} {{ backend.backend }}
   agent:
     type: Unity::VM
     image: package-ci/ubuntu:v1.3.1-719011
       python -m pip install pyyaml --index-url https://artifactory.prd.it.unity3d.com/artifactory/api/pypi/pypi/simple
       python -u -m ml-agents.tests.yamato.training_int_tests
   dependencies:
-    - .yamato/standalone-build-test.yml#test_linux_standalone_{{ editor.version }}
+    - .yamato/standalone-build-test.yml#test_linux_standalone_{{ editor.version }}_{{ backend.backend }}
   triggers:
     cancel_old_ci: true
     expression: |
         - "artifacts/testPlayer*/**"
         - "artifacts/models/**"
 {% endfor %}
+{% endfor %}

.yamato/standalone-build-test.yml

 {% metadata_file .yamato/test_versions.metafile %}
 ---
 {% for editor in test_editors %}
-test_linux_standalone_{{ editor.version }}:
-  name: Test Linux Standalone {{ editor.version }}
+{% for backend in scripting_backends %}
+test_linux_standalone_{{ editor.version }}_{{ backend.backend }}:
+  name: Test Linux Standalone {{ editor.version }} {{ backend.backend }}
   agent:
     type: Unity::VM
     image: package-ci/ubuntu:v1.3.1-719011
   commands:
+    - sudo apt-get install -y lld
-    - unity-downloader-cli -u {{ editor.version }} -c editor --wait --fast
-    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux
-    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --scene=Assets/ML-Agents/Examples/Basic/Scenes/Basic.unity
-    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --scene=Assets/ML-Agents/Examples/Match3/Scenes/Match3.unity
-    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --scene=Assets/ML-Agents/Examples/WallJump/Scenes/WallJump.unity
-    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --scene=Assets/ML-Agents/TestScenes/TestCompressedGrid/TestGridCompressed.unity
-    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --scene=Assets/ML-Agents/TestScenes/TestCompressedTexture/TestTextureCompressed.unity
+    - unity-downloader-cli -u {{ editor.version }} -c editor -c il2cpp --wait --fast
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --mlagents-scripting-backend={{ backend.backend }}
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --scene=Assets/ML-Agents/Examples/Basic/Scenes/Basic.unity --mlagents-scripting-backend={{ backend.backend }}
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --scene=Assets/ML-Agents/Examples/Match3/Scenes/Match3.unity --mlagents-scripting-backend={{ backend.backend }}
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --scene=Assets/ML-Agents/Examples/WallJump/Scenes/WallJump.unity --mlagents-scripting-backend={{ backend.backend }}
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --scene=Assets/ML-Agents/TestScenes/TestCompressedGrid/TestGridCompressed.unity --mlagents-scripting-backend={{ backend.backend }}
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --build-target=linux --scene=Assets/ML-Agents/TestScenes/TestCompressedTexture/TestTextureCompressed.unity --mlagents-scripting-backend={{ backend.backend }}
   triggers:
     cancel_old_ci: true
     expression: |
         - "artifacts/testPlayer*/**"
         - "artifacts/**/UnityPlayer.so"
 {% endfor %}
+{% endfor %}

com.unity.ml-agents/Plugins/ProtoBuffer/link.xml

-<?xml version="1.0" encoding="utf-8"?>
-<linker>
-<!--
-Prevents Managed code stripping from removing code necessary for training.
-You may wish to disable this preservation (that is, re-enable code stripping) to
-reduce code size if you no longer need training. 
-See also https://docs.unity3d.com/Manual/ManagedCodeStripping.html
--->
-    <assembly fullname="Grpc.Core" preserve="all"/>
-</linker>

com.unity.ml-agents/Plugins/ProtoBuffer/link.xml.meta

-fileFormatVersion: 2
-guid: f94355fa6eab94c2d8529747b92ca3e1
-TextScriptImporter:
-  externalObjects: {}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: