fix pty output make main process oom

src/vs/base/parts/ipc/common/ipc.ts

@@ -1103,7 +1103,14 @@ export namespace ProxyChannel {
 		disableMarshalling?: boolean;
 	}
 
-	export interface ICreateServiceChannelOptions extends IProxyOptions { }
+	export interface ICreateServiceChannelOptions extends IProxyOptions {
+		/**
+		 * If an event is triggered automatically but may not have subscribers,
+		 * then `isLazyEvent` should return `true`. Otherwise the event data will
+		 * be cached in the buffer which causing a memory leak
+		 */
+		isLazyEvent?: (key: string) => boolean;
+	}
 
 	export function fromService<TContext>(service: unknown, disposables: DisposableStore, options?: ICreateServiceChannelOptions): IServerChannel<TContext> {
 		const handler = service as { [key: string]: unknown };
@@ -1117,6 +1124,9 @@ export namespace ProxyChannel {
 		const mapEventNameToEvent = new Map<string, Event<unknown>>();
 		for (const key in handler) {
 			if (propertyIsEvent(key)) {
+				if (options?.isLazyEvent?.(key)) {
+					continue;
+				}
 				mapEventNameToEvent.set(key, Event.buffer(handler[key] as Event<unknown>, true, undefined, disposables));
 			}
 		}

src/vs/base/parts/ipc/test/common/ipc.test.ts

@@ -508,4 +508,43 @@ suite('Base IPC', function () {
 			client2.dispose();
 		});
 	});
+
+	suite('handle event lazily', function () {
+		let server: IPCServer;
+		let client: IPCClient;
+		let service: TestService;
+		let ipcService: ITestService;
+		const disposables = new DisposableStore();
+
+		setup(function () {
+			service = store.add(new TestService());
+			const testServer = disposables.add(new TestIPCServer());
+			server = testServer;
+
+			server.registerChannel(TestChannelId, ProxyChannel.fromService(service, disposables, { isLazyEvent: key => key === 'onPong' }));
+
+			client = disposables.add(testServer.createConnection('client1'));
+			ipcService = ProxyChannel.toService(client.getChannel(TestChannelId));
+		});
+
+		teardown(function () {
+			disposables.clear();
+		});
+
+		test('lazy event buffer', async function () {
+			// This message should be dropped
+			service.ping('hello 1');
+			// Listener should be called only once and the message should be 'hello 2'
+			const promise = new Promise(resolve => {
+				disposables.add(ipcService.onPong(msg => {
+					assert.strictEqual(msg, 'hello 2');
+					resolve(undefined);
+				}));
+			});
+			// This message should be received
+			service.ping('hello 2');
+			await promise;
+		});
+
+	});
 });

src/vs/code/electron-main/app.ts

@@ -1212,7 +1212,9 @@ export class CodeApplication extends Disposable {
 		sharedProcessClient.then(client => client.registerChannel('profileStorageListener', profileStorageListener));
 
 		// Terminal
-		const ptyHostChannel = ProxyChannel.fromService(accessor.get(ILocalPtyService), disposables);
+		const ptyHostChannel = ProxyChannel.fromService(accessor.get(ILocalPtyService), disposables, {
+			isLazyEvent: (key: string) => key === 'onProcessData'
+		});
 		mainProcessElectronServer.registerChannel(TerminalIpcChannels.LocalPty, ptyHostChannel);
 
 		// External Terminal