add extension host heart beat and log telemetry event when ext host goes dark, #14758

src/vs/workbench/node/extensionHostProcess.ts

@@ -106,6 +106,12 @@ function connectToRenderer(): TPromise<IRendererConnection> {
 				stats.length = 0;
 			}, 1000);
 
+
+			// Send heartbeat
+			setInterval(function () {
+				queuedSender.send('__$heartbeat');
+			}, 250);
+
 			// Tell the outside that we are initialized
 			queuedSender.send('initialized');
 
@@ -121,4 +127,4 @@ connectToRenderer().then(renderer => {
 	const extensionHostMain = new ExtensionHostMain(renderer.remoteCom, renderer.initData);
 	onTerminate = () => extensionHostMain.terminate();
 	return extensionHostMain.start();
-}).done(null, err => console.error(err));
+}).done(null, err => console.error(err));