azuredatastudio/src/vs/workbench/services/extensions/electron-browser/localProcessExtensionHost.ts

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the Source EULA. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import * as nls from 'vs/nls';
import { ChildProcess, fork } from 'child_process';
import { Server, Socket, createServer } from 'net';
import { CrashReporterStartOptions } from 'vs/base/parts/sandbox/electron-sandbox/electronTypes';
import { FileAccess } from 'vs/base/common/network';
import { timeout } from 'vs/base/common/async';
import { toErrorMessage } from 'vs/base/common/errorMessage';
import { Emitter, Event } from 'vs/base/common/event';
import { toDisposable, DisposableStore } from 'vs/base/common/lifecycle';
import * as objects from 'vs/base/common/objects';
import * as platform from 'vs/base/common/platform';
import { URI } from 'vs/base/common/uri';
import { IRemoteConsoleLog, log } from 'vs/base/common/console';
import { logRemoteEntry } from 'vs/workbench/services/extensions/common/remoteConsoleUtil';
import { findFreePort } from 'vs/base/node/ports';
import { IMessagePassingProtocol } from 'vs/base/parts/ipc/common/ipc';
import { PersistentProtocol } from 'vs/base/parts/ipc/common/ipc.net';
import { createRandomIPCHandle, NodeSocket } from 'vs/base/parts/ipc/node/ipc.net';
import { INativeWorkbenchEnvironmentService } from 'vs/workbench/services/environment/electron-sandbox/environmentService';
import { ILabelService } from 'vs/platform/label/common/label';
import { ILifecycleService, WillShutdownEvent } from 'vs/workbench/services/lifecycle/common/lifecycle';
import { ILogService } from 'vs/platform/log/common/log';
import { IProductService } from 'vs/platform/product/common/productService';
import { INotificationService, Severity } from 'vs/platform/notification/common/notification';
import { ITelemetryService } from 'vs/platform/telemetry/common/telemetry';
import { INativeHostService } from 'vs/platform/native/electron-sandbox/native';
import { IWorkspaceContextService, WorkbenchState } from 'vs/platform/workspace/common/workspace';
import { IInitData, UIKind } from 'vs/workbench/api/common/extHost.protocol';
import { MessageType, createMessageOfType, isMessageOfType } from 'vs/workbench/services/extensions/common/extensionHostProtocol';
import { withNullAsUndefined } from 'vs/base/common/types';
import { IExtensionDescription } from 'vs/platform/extensions/common/extensions';
import { parseExtensionDevOptions } from '../common/extensionDevOptions';
import { VSBuffer } from 'vs/base/common/buffer';
import { IExtensionHostDebugService } from 'vs/platform/debug/common/extensionHostDebug';
import { IExtensionHost, ExtensionHostLogFileName, ExtensionHostKind } from 'vs/workbench/services/extensions/common/extensions';
import { isUntitledWorkspace } from 'vs/platform/workspaces/common/workspaces';
import { IHostService } from 'vs/workbench/services/host/browser/host';
import { joinPath } from 'vs/base/common/resources';
import { Registry } from 'vs/platform/registry/common/platform';
import { IOutputChannelRegistry, Extensions } from 'vs/workbench/services/output/common/output';
import { isUUID } from 'vs/base/common/uuid';
import { join } from 'vs/base/common/path';
import { Readable, Writable } from 'stream';
import { StringDecoder } from 'string_decoder';
import { IShellEnvironmentService } from 'vs/workbench/services/environment/electron-sandbox/shellEnvironmentService';

export interface ILocalProcessExtensionHostInitData {
	readonly autoStart: boolean;
	readonly extensions: IExtensionDescription[];
}

export interface ILocalProcessExtensionHostDataProvider {
	getInitData(): Promise<ILocalProcessExtensionHostInitData>;
}

const enum NativeLogMarkers {
	Start = 'START_NATIVE_LOG',
	End = 'END_NATIVE_LOG',
}

export class LocalProcessExtensionHost implements IExtensionHost {

	public readonly kind = ExtensionHostKind.LocalProcess;
	public readonly remoteAuthority = null;
	public readonly lazyStart = false;

	private readonly _onExit: Emitter<[number, string]> = new Emitter<[number, string]>();
	public readonly onExit: Event<[number, string]> = this._onExit.event;

	private readonly _onDidSetInspectPort = new Emitter<void>();

	private readonly _toDispose = new DisposableStore();

	private readonly _isExtensionDevHost: boolean;
	private readonly _isExtensionDevDebug: boolean;
	private readonly _isExtensionDevDebugBrk: boolean;
	private readonly _isExtensionDevTestFromCli: boolean;

	// State
	private _lastExtensionHostError: string | null;
	private _terminating: boolean;

	// Resources, in order they get acquired/created when .start() is called:
	private _namedPipeServer: Server | null;
	private _inspectPort: number | null;
	private _extensionHostProcess: ChildProcess | null;
	private _extensionHostConnection: Socket | null;
	private _messageProtocol: Promise<PersistentProtocol> | null;

	private readonly _extensionHostLogFile: URI;

	constructor(
		private readonly _initDataProvider: ILocalProcessExtensionHostDataProvider,
		@IWorkspaceContextService private readonly _contextService: IWorkspaceContextService,
		@INotificationService private readonly _notificationService: INotificationService,
		@INativeHostService private readonly _nativeHostService: INativeHostService,
		@ILifecycleService private readonly _lifecycleService: ILifecycleService,
		@INativeWorkbenchEnvironmentService private readonly _environmentService: INativeWorkbenchEnvironmentService,
		@ITelemetryService private readonly _telemetryService: ITelemetryService,
		@ILogService private readonly _logService: ILogService,
		@ILabelService private readonly _labelService: ILabelService,
		@IExtensionHostDebugService private readonly _extensionHostDebugService: IExtensionHostDebugService,
		@IHostService private readonly _hostService: IHostService,
		@IProductService private readonly _productService: IProductService,
		@IShellEnvironmentService private readonly _shellEnvironmentService: IShellEnvironmentService
	) {
		const devOpts = parseExtensionDevOptions(this._environmentService);
		this._isExtensionDevHost = devOpts.isExtensionDevHost;
		this._isExtensionDevDebug = devOpts.isExtensionDevDebug;
		this._isExtensionDevDebugBrk = devOpts.isExtensionDevDebugBrk;
		this._isExtensionDevTestFromCli = devOpts.isExtensionDevTestFromCli;

		this._lastExtensionHostError = null;
		this._terminating = false;

		this._namedPipeServer = null;
		this._inspectPort = null;
		this._extensionHostProcess = null;
		this._extensionHostConnection = null;
		this._messageProtocol = null;

		this._extensionHostLogFile = joinPath(this._environmentService.extHostLogsPath, `${ExtensionHostLogFileName}.log`);

		this._toDispose.add(this._onExit);
		this._toDispose.add(this._lifecycleService.onWillShutdown(e => this._onWillShutdown(e)));
		this._toDispose.add(this._lifecycleService.onDidShutdown(reason => this.terminate()));
		this._toDispose.add(this._extensionHostDebugService.onClose(event => {
			if (this._isExtensionDevHost && this._environmentService.debugExtensionHost.debugId === event.sessionId) {
				this._nativeHostService.closeWindow();
			}
		}));
		this._toDispose.add(this._extensionHostDebugService.onReload(event => {
			if (this._isExtensionDevHost && this._environmentService.debugExtensionHost.debugId === event.sessionId) {
				this._hostService.reload();
			}
		}));

		const globalExitListener = () => this.terminate();
		process.once('exit', globalExitListener);
		this._toDispose.add(toDisposable(() => {
			process.removeListener('exit' as 'loaded', globalExitListener); // https://github.com/electron/electron/issues/21475
		}));
	}

	public dispose(): void {
		this.terminate();
	}

	public start(): Promise<IMessagePassingProtocol> | null {
		if (this._terminating) {
			// .terminate() was called
			return null;
		}

		if (!this._messageProtocol) {
			this._messageProtocol = Promise.all([
				this._tryListenOnPipe(),
				this._tryFindDebugPort(),
				this._shellEnvironmentService.getShellEnv()
			]).then(([pipeName, portNumber, processEnv]) => {
				const env = objects.mixin(processEnv, {
					VSCODE_AMD_ENTRYPOINT: 'vs/workbench/services/extensions/node/extensionHostProcess',
					VSCODE_PIPE_LOGGING: 'true',
					VSCODE_VERBOSE_LOGGING: true,
					VSCODE_LOG_NATIVE: this._isExtensionDevHost,
					VSCODE_IPC_HOOK_EXTHOST: pipeName,
					VSCODE_HANDLES_UNCAUGHT_ERRORS: true,
					VSCODE_LOG_STACK: !this._isExtensionDevTestFromCli && (this._isExtensionDevHost || !this._environmentService.isBuilt || this._productService.quality !== 'stable' || this._environmentService.verbose),
					VSCODE_LOG_LEVEL: this._environmentService.verbose ? 'trace' : this._environmentService.log
				});

				if (platform.isMacintosh) {
					// Unset `DYLD_LIBRARY_PATH`, as it leads to extension host crashes
					// See https://github.com/microsoft/vscode/issues/104525
					delete env['DYLD_LIBRARY_PATH'];
				}

				if (this._isExtensionDevHost) {
					// Unset `VSCODE_CODE_CACHE_PATH` when developing extensions because it might
					// be that dependencies, that otherwise would be cached, get modified.
					delete env['VSCODE_CODE_CACHE_PATH'];
				}

				const opts = {
					env,
					// We only detach the extension host on windows. Linux and Mac orphan by default
					// and detach under Linux and Mac create another process group.
					// We detach because we have noticed that when the renderer exits, its child processes
					// (i.e. extension host) are taken down in a brutal fashion by the OS
					detached: !!platform.isWindows,
					execArgv: undefined as string[] | undefined,
					silent: true
				};

				if (portNumber !== 0) {
					opts.execArgv = [
						'--nolazy',
						(this._isExtensionDevDebugBrk ? '--inspect-brk=' : '--inspect=') + portNumber
					];
				} else {
					opts.execArgv = ['--inspect-port=0'];
				}

				if (this._environmentService.args['prof-v8-extensions']) {
					opts.execArgv.unshift('--prof');
				}

				if (this._environmentService.args['max-memory']) {
					opts.execArgv.unshift(`--max-old-space-size=${this._environmentService.args['max-memory']}`);
				}

				// On linux crash reporter needs to be started on child node processes explicitly
				if (platform.isLinux) {
					const crashReporterStartOptions: CrashReporterStartOptions = {
						companyName: this._productService.crashReporter?.companyName || 'Microsoft',
						productName: this._productService.crashReporter?.productName || this._productService.nameShort,
						submitURL: '',
						uploadToServer: false
					};
					const crashReporterId = this._environmentService.crashReporterId; // crashReporterId is set by the main process only when crash reporting is enabled by the user.
					const appcenter = this._productService.appCenter;
					const uploadCrashesToServer = !this._environmentService.crashReporterDirectory; // only upload unless --crash-reporter-directory is provided
					if (uploadCrashesToServer && appcenter && crashReporterId && isUUID(crashReporterId)) {
						const submitURL = appcenter[`linux-x64`];
						crashReporterStartOptions.submitURL = submitURL.concat('&uid=', crashReporterId, '&iid=', crashReporterId, '&sid=', crashReporterId);
						crashReporterStartOptions.uploadToServer = true;
					}
					// In the upload to server case, there is a bug in electron that creates client_id file in the current
					// working directory. Setting the env BREAKPAD_DUMP_LOCATION will force electron to create the file in that location,
					// For https://github.com/microsoft/vscode/issues/105743
					const extHostCrashDirectory = this._environmentService.crashReporterDirectory || this._environmentService.userDataPath;
					opts.env.BREAKPAD_DUMP_LOCATION = join(extHostCrashDirectory, `${ExtensionHostLogFileName} Crash Reports`);
					opts.env.VSCODE_CRASH_REPORTER_START_OPTIONS = JSON.stringify(crashReporterStartOptions);
				}

				// Run Extension Host as fork of current process
				this._extensionHostProcess = fork(FileAccess.asFileUri('bootstrap-fork', require).fsPath, ['--type=extensionHost', '--skipWorkspaceStorageLock'], opts);

				// Catch all output coming from the extension host process
				type Output = { data: string, format: string[] };
				const onStdout = this._handleProcessOutputStream(this._extensionHostProcess.stdout!);
				const onStderr = this._handleProcessOutputStream(this._extensionHostProcess.stderr!);
				const onOutput = Event.any(
					Event.map(onStdout.event, o => ({ data: `%c${o}`, format: [''] })),
					Event.map(onStderr.event, o => ({ data: `%c${o}`, format: ['color: red'] }))
				);

				// Debounce all output, so we can render it in the Chrome console as a group
				const onDebouncedOutput = Event.debounce<Output>(onOutput, (r, o) => {
					return r
						? { data: r.data + o.data, format: [...r.format, ...o.format] }
						: { data: o.data, format: o.format };
				}, 100);

				// Print out extension host output
				onDebouncedOutput(output => {
					const inspectorUrlMatch = output.data && output.data.match(/ws:\/\/([^\s]+:(\d+)\/[^\s]+)/);
					if (inspectorUrlMatch) {
						if (!this._environmentService.isBuilt && !this._isExtensionDevTestFromCli) {
							console.log(`%c[Extension Host] %cdebugger inspector at chrome-devtools://devtools/bundled/inspector.html?experiments=true&v8only=true&ws=${inspectorUrlMatch[1]}`, 'color: blue', 'color:');
						}
						if (!this._inspectPort) {
							this._inspectPort = Number(inspectorUrlMatch[2]);
							this._onDidSetInspectPort.fire();
						}
					} else {
						if (!this._isExtensionDevTestFromCli) {
							console.group('Extension Host');
							console.log(output.data, ...output.format);
							console.groupEnd();
						}
					}
				});

				// Support logging from extension host
				this._extensionHostProcess.on('message', msg => {
					if (msg && (<IRemoteConsoleLog>msg).type === '__$console') {
						this._logExtensionHostMessage(<IRemoteConsoleLog>msg);
					}
				});

				// Lifecycle
				this._extensionHostProcess.on('error', (err) => this._onExtHostProcessError(err));
				this._extensionHostProcess.on('exit', (code: number, signal: string) => this._onExtHostProcessExit(code, signal));

				// Notify debugger that we are ready to attach to the process if we run a development extension
				if (portNumber) {
					if (this._isExtensionDevHost && portNumber && this._isExtensionDevDebug && this._environmentService.debugExtensionHost.debugId) {
						this._extensionHostDebugService.attachSession(this._environmentService.debugExtensionHost.debugId, portNumber);
					}
					this._inspectPort = portNumber;
					this._onDidSetInspectPort.fire();
				}

				// Help in case we fail to start it
				let startupTimeoutHandle: any;
				if (!this._environmentService.isBuilt && !this._environmentService.remoteAuthority || this._isExtensionDevHost) {
					startupTimeoutHandle = setTimeout(() => {
						const msg = this._isExtensionDevDebugBrk
							? nls.localize('extensionHost.startupFailDebug', "Extension host did not start in 10 seconds, it might be stopped on the first line and needs a debugger to continue.")
							: nls.localize('extensionHost.startupFail', "Extension host did not start in 10 seconds, that might be a problem.");

						this._notificationService.prompt(Severity.Warning, msg,
							[{
								label: nls.localize('reloadWindow', "Reload Window"),
								run: () => this._hostService.reload()
							}],
							{ sticky: true }
						);
					}, 10000);
				}

				// Initialize extension host process with hand shakes
				return this._tryExtHostHandshake().then((protocol) => {
					clearTimeout(startupTimeoutHandle);
					return protocol;
				});
			});
		}

		return this._messageProtocol;
	}

	/**
	 * Start a server (`this._namedPipeServer`) that listens on a named pipe and return the named pipe name.
	 */
	private _tryListenOnPipe(): Promise<string> {
		return new Promise<string>((resolve, reject) => {
			const pipeName = createRandomIPCHandle();

			this._namedPipeServer = createServer();
			this._namedPipeServer.on('error', reject);
			this._namedPipeServer.listen(pipeName, () => {
				if (this._namedPipeServer) {
					this._namedPipeServer.removeListener('error', reject);
				}
				resolve(pipeName);
			});
		});
	}

	/**
	 * Find a free port if extension host debugging is enabled.
	 */
	private async _tryFindDebugPort(): Promise<number> {

		if (typeof this._environmentService.debugExtensionHost.port !== 'number') {
			return 0;
		}

		const expected = this._environmentService.debugExtensionHost.port;
		const port = await findFreePort(expected, 10 /* try 10 ports */, 5000 /* try up to 5 seconds */);

		if (!this._isExtensionDevTestFromCli) {
			if (!port) {
				console.warn('%c[Extension Host] %cCould not find a free port for debugging', 'color: blue', 'color:');
			} else {
				if (port !== expected) {
					console.warn(`%c[Extension Host] %cProvided debugging port ${expected} is not free, using ${port} instead.`, 'color: blue', 'color:');
				}
				if (this._isExtensionDevDebugBrk) {
					console.warn(`%c[Extension Host] %cSTOPPED on first line for debugging on port ${port}`, 'color: blue', 'color:');
				} else {
					console.info(`%c[Extension Host] %cdebugger listening on port ${port}`, 'color: blue', 'color:');
				}
			}
		}

		return port || 0;
	}

	private _tryExtHostHandshake(): Promise<PersistentProtocol> {

		return new Promise<PersistentProtocol>((resolve, reject) => {

			// Wait for the extension host to connect to our named pipe
			// and wrap the socket in the message passing protocol
			let handle = setTimeout(() => {
				if (this._namedPipeServer) {
					this._namedPipeServer.close();
					this._namedPipeServer = null;
				}
				reject('timeout');
			}, 60 * 1000);

			this._namedPipeServer!.on('connection', socket => {
				clearTimeout(handle);
				if (this._namedPipeServer) {
					this._namedPipeServer.close();
					this._namedPipeServer = null;
				}
				this._extensionHostConnection = socket;

				// using a buffered message protocol here because between now
				// and the first time a `then` executes some messages might be lost
				// unless we immediately register a listener for `onMessage`.
				resolve(new PersistentProtocol(new NodeSocket(this._extensionHostConnection)));
			});

		}).then((protocol) => {

			// 1) wait for the incoming `ready` event and send the initialization data.
			// 2) wait for the incoming `initialized` event.
			return new Promise<PersistentProtocol>((resolve, reject) => {

				let timeoutHandle: NodeJS.Timer;
				const installTimeoutCheck = () => {
					timeoutHandle = setTimeout(() => {
						reject('timeout');
					}, 60 * 1000);
				};
				const uninstallTimeoutCheck = () => {
					clearTimeout(timeoutHandle);
				};

				// Wait 60s for the ready message
				installTimeoutCheck();

				const disposable = protocol.onMessage(msg => {

					if (isMessageOfType(msg, MessageType.Ready)) {
						// 1) Extension Host is ready to receive messages, initialize it
						uninstallTimeoutCheck();

						this._createExtHostInitData().then(data => {

							// Wait 60s for the initialized message
							installTimeoutCheck();

							protocol.send(VSBuffer.fromString(JSON.stringify(data)));
						});
						return;
					}

					if (isMessageOfType(msg, MessageType.Initialized)) {
						// 2) Extension Host is initialized
						uninstallTimeoutCheck();

						// stop listening for messages here
						disposable.dispose();

						// Register log channel for exthost log
						Registry.as<IOutputChannelRegistry>(Extensions.OutputChannels).registerChannel({ id: 'extHostLog', label: nls.localize('extension host Log', "Extension Host"), file: this._extensionHostLogFile, log: true });

						// release this promise
						resolve(protocol);
						return;
					}

					console.error(`received unexpected message during handshake phase from the extension host: `, msg);
				});

			});

		});
	}

	private async _createExtHostInitData(): Promise<IInitData> {
		const [telemetryInfo, initData] = await Promise.all([this._telemetryService.getTelemetryInfo(), this._initDataProvider.getInitData()]);
		const workspace = this._contextService.getWorkspace();
		return {
			commit: this._productService.commit,
			version: this._productService.version,
			vscodeVersion: this._productService.vscodeVersion, // {{SQL CARBON EDIT}} add vscode version
			parentPid: process.pid,
			environment: {
				isExtensionDevelopmentDebug: this._isExtensionDevDebug,
				appRoot: this._environmentService.appRoot ? URI.file(this._environmentService.appRoot) : undefined,
				appName: this._productService.nameLong,
				embedderIdentifier: this._productService.embedderIdentifier || 'desktop',
				appUriScheme: this._productService.urlProtocol,
				appLanguage: platform.language,
				extensionDevelopmentLocationURI: this._environmentService.extensionDevelopmentLocationURI,
				extensionTestsLocationURI: this._environmentService.extensionTestsLocationURI,
				globalStorageHome: this._environmentService.globalStorageHome,
				workspaceStorageHome: this._environmentService.workspaceStorageHome,
			},
			workspace: this._contextService.getWorkbenchState() === WorkbenchState.EMPTY ? undefined : {
				configuration: withNullAsUndefined(workspace.configuration),
				id: workspace.id,
				name: this._labelService.getWorkspaceLabel(workspace),
				isUntitled: workspace.configuration ? isUntitledWorkspace(workspace.configuration, this._environmentService) : false
			},
			remote: {
				authority: this._environmentService.remoteAuthority,
				connectionData: null,
				isRemote: false
			},
			resolvedExtensions: [],
			hostExtensions: [],
			extensions: initData.extensions,
			telemetryInfo,
			logLevel: this._logService.getLevel(),
			logsLocation: this._environmentService.extHostLogsPath,
			logFile: this._extensionHostLogFile,
			autoStart: initData.autoStart,
			uiKind: UIKind.Desktop
		};
	}

	private _logExtensionHostMessage(entry: IRemoteConsoleLog) {

		if (this._isExtensionDevTestFromCli) {

			// Log on main side if running tests from cli
			logRemoteEntry(this._logService, entry);
		} else {

			// Send to local console
			log(entry, 'Extension Host');
		}
	}

	private _onExtHostProcessError(err: any): void {
		let errorMessage = toErrorMessage(err);
		if (errorMessage === this._lastExtensionHostError) {
			return; // prevent error spam
		}

		this._lastExtensionHostError = errorMessage;

		this._notificationService.error(nls.localize('extensionHost.error', "Error from the extension host: {0}", errorMessage));
	}

	private _onExtHostProcessExit(code: number, signal: string): void {
		if (this._terminating) {
			// Expected termination path (we asked the process to terminate)
			return;
		}

		this._onExit.fire([code, signal]);
	}

	private _handleProcessOutputStream(stream: Readable) {
		let last = '';
		let isOmitting = false;
		const event = new Emitter<string>();
		const decoder = new StringDecoder('utf-8');
		stream.pipe(new Writable({
			write(chunk, _encoding, callback) {
				// not a fancy approach, but this is the same approach used by the split2
				// module which is well-optimized (https://github.com/mcollina/split2)
				last += typeof chunk === 'string' ? chunk : decoder.write(chunk);
				let lines = last.split(/\r?\n/g);
				last = lines.pop()!;

				// protected against an extension spamming and leaking memory if no new line is written.
				if (last.length > 10_000) {
					lines.push(last);
					last = '';
				}

				for (const line of lines) {
					if (isOmitting) {
						if (line === NativeLogMarkers.End) {
							isOmitting = false;
						}
					} else if (line === NativeLogMarkers.Start) {
						isOmitting = true;
					} else if (line.length) {
						event.fire(line + '\n');
					}
				}

				callback();
			}
		}));

		return event;
	}

	public async enableInspectPort(): Promise<boolean> {
		if (typeof this._inspectPort === 'number') {
			return true;
		}

		if (!this._extensionHostProcess) {
			return false;
		}

		interface ProcessExt {
			_debugProcess?(n: number): any;
		}

		if (typeof (<ProcessExt>process)._debugProcess === 'function') {
			// use (undocumented) _debugProcess feature of node
			(<ProcessExt>process)._debugProcess!(this._extensionHostProcess.pid);
			await Promise.race([Event.toPromise(this._onDidSetInspectPort.event), timeout(1000)]);
			return typeof this._inspectPort === 'number';

		} else if (!platform.isWindows) {
			// use KILL USR1 on non-windows platforms (fallback)
			this._extensionHostProcess.kill('SIGUSR1');
			await Promise.race([Event.toPromise(this._onDidSetInspectPort.event), timeout(1000)]);
			return typeof this._inspectPort === 'number';

		} else {
			// not supported...
			return false;
		}
	}

	public getInspectPort(): number | undefined {
		return withNullAsUndefined(this._inspectPort);
	}

	public terminate(): void {
		if (this._terminating) {
			return;
		}
		this._terminating = true;

		this._toDispose.dispose();

		if (!this._messageProtocol) {
			// .start() was not called
			return;
		}

		this._messageProtocol.then((protocol) => {

			// Send the extension host a request to terminate itself
			// (graceful termination)
			protocol.send(createMessageOfType(MessageType.Terminate));

			protocol.getSocket().dispose();

			protocol.dispose();

			// Give the extension host 10s, after which we will
			// try to kill the process and release any resources
			setTimeout(() => this._cleanResources(), 10 * 1000);

		}, (err) => {

			// Establishing a protocol with the extension host failed, so
			// try to kill the process and release any resources.
			this._cleanResources();
		});
	}

	private _cleanResources(): void {
		if (this._namedPipeServer) {
			this._namedPipeServer.close();
			this._namedPipeServer = null;
		}
		if (this._extensionHostConnection) {
			this._extensionHostConnection.end();
			this._extensionHostConnection = null;
		}
		if (this._extensionHostProcess) {
			this._extensionHostProcess.kill();
			this._extensionHostProcess = null;
		}
	}

	private _onWillShutdown(event: WillShutdownEvent): void {

		// If the extension development host was started without debugger attached we need
		// to communicate this back to the main side to terminate the debug session
		if (this._isExtensionDevHost && !this._isExtensionDevTestFromCli && !this._isExtensionDevDebug && this._environmentService.debugExtensionHost.debugId) {
			this._extensionHostDebugService.terminateSession(this._environmentService.debugExtensionHost.debugId);
			event.join(timeout(100 /* wait a bit for IPC to get delivered */), 'join.extensionDevelopment');
		}
	}
}