fix(core): Fix task runner sending too many offers (#12415)

packages/@n8n/task-runner/src/js-task-runner/__tests__/task-runner.test.ts

@@ -1,32 +1,44 @@
 import { WebSocket } from 'ws';
 
-import { TaskRunner } from '@/task-runner';
+import { TaskRunner, type TaskRunnerOpts } from '@/task-runner';
 
 class TestRunner extends TaskRunner {}
 
 jest.mock('ws');
 
 describe('TestRunner', () => {
+	let runner: TestRunner;
+
+	const newTestRunner = (opts: Partial<TaskRunnerOpts> = {}) =>
+		new TestRunner({
+			taskType: 'test-task',
+			maxConcurrency: 5,
+			idleTimeout: 60,
+			grantToken: 'test-token',
+			maxPayloadSize: 1024,
+			taskBrokerUri: 'http://localhost:8080',
+			timezone: 'America/New_York',
+			taskTimeout: 60,
+			healthcheckServer: {
+				enabled: false,
+				host: 'localhost',
+				port: 8081,
+			},
+			...opts,
+		});
+
+	afterEach(() => {
+		runner?.clearIdleTimer();
+	});
+
 	describe('constructor', () => {
 		afterEach(() => {
 			jest.clearAllMocks();
 		});
 
 		it('should correctly construct WebSocket URI with provided taskBrokerUri', () => {
-			const runner = new TestRunner({
-				taskType: 'test-task',
-				maxConcurrency: 5,
-				idleTimeout: 60,
-				grantToken: 'test-token',
-				maxPayloadSize: 1024,
+			runner = newTestRunner({
 				taskBrokerUri: 'http://localhost:8080',
-				timezone: 'America/New_York',
-				taskTimeout: 60,
-				healthcheckServer: {
-					enabled: false,
-					host: 'localhost',
-					port: 8081,
-				},
 			});
 
 			expect(WebSocket).toHaveBeenCalledWith(
@@ -38,25 +50,11 @@ describe('TestRunner', () => {
 					maxPayload: 1024,
 				}),
 			);
-
-			runner.clearIdleTimer();
 		});
 
 		it('should handle different taskBrokerUri formats correctly', () => {
-			const runner = new TestRunner({
-				taskType: 'test-task',
-				maxConcurrency: 5,
-				idleTimeout: 60,
-				grantToken: 'test-token',
-				maxPayloadSize: 1024,
+			runner = newTestRunner({
 				taskBrokerUri: 'https://example.com:3000/path',
-				timezone: 'America/New_York',
-				taskTimeout: 60,
-				healthcheckServer: {
-					enabled: false,
-					host: 'localhost',
-					port: 8081,
-				},
 			});
 
 			expect(WebSocket).toHaveBeenCalledWith(
@@ -68,49 +66,140 @@ describe('TestRunner', () => {
 					maxPayload: 1024,
 				}),
 			);
-
-			runner.clearIdleTimer();
 		});
 
 		it('should throw an error if taskBrokerUri is invalid', () => {
-			expect(
-				() =>
-					new TestRunner({
-						taskType: 'test-task',
-						maxConcurrency: 5,
-						idleTimeout: 60,
-						grantToken: 'test-token',
-						maxPayloadSize: 1024,
-						taskBrokerUri: 'not-a-valid-uri',
-						timezone: 'America/New_York',
-						taskTimeout: 60,
-						healthcheckServer: {
-							enabled: false,
-							host: 'localhost',
-							port: 8081,
-						},
-					}),
+			expect(() =>
+				newTestRunner({
+					taskBrokerUri: 'not-a-valid-uri',
+				}),
 			).toThrowError(/Invalid URL/);
 		});
 	});
 
+	describe('sendOffers', () => {
+		beforeEach(() => {
+			jest.useFakeTimers();
+		});
+
+		afterEach(() => {
+			jest.clearAllTimers();
+		});
+
+		it('should not send offers if canSendOffers is false', () => {
+			runner = newTestRunner({
+				taskType: 'test-task',
+				maxConcurrency: 2,
+			});
+			const sendSpy = jest.spyOn(runner, 'send');
+			expect(runner.canSendOffers).toBe(false);
+
+			runner.sendOffers();
+
+			expect(sendSpy).toHaveBeenCalledTimes(0);
+		});
+
+		it('should enable sending of offer on runnerregistered message', () => {
+			runner = newTestRunner({
+				taskType: 'test-task',
+				maxConcurrency: 2,
+			});
+			runner.onMessage({
+				type: 'broker:runnerregistered',
+			});
+
+			expect(runner.canSendOffers).toBe(true);
+		});
+
+		it('should send maxConcurrency offers when there are no offers', () => {
+			runner = newTestRunner({
+				taskType: 'test-task',
+				maxConcurrency: 2,
+			});
+			runner.onMessage({
+				type: 'broker:runnerregistered',
+			});
+
+			const sendSpy = jest.spyOn(runner, 'send');
+
+			runner.sendOffers();
+			runner.sendOffers();
+
+			expect(sendSpy).toHaveBeenCalledTimes(2);
+			expect(sendSpy.mock.calls).toEqual([
+				[
+					{
+						type: 'runner:taskoffer',
+						taskType: 'test-task',
+						offerId: expect.any(String),
+						validFor: expect.any(Number),
+					},
+				],
+				[
+					{
+						type: 'runner:taskoffer',
+						taskType: 'test-task',
+						offerId: expect.any(String),
+						validFor: expect.any(Number),
+					},
+				],
+			]);
+		});
+
+		it('should send up to maxConcurrency offers when there is a running task', () => {
+			runner = newTestRunner({
+				taskType: 'test-task',
+				maxConcurrency: 2,
+			});
+			runner.onMessage({
+				type: 'broker:runnerregistered',
+			});
+			runner.runningTasks.set('test-task', {
+				taskId: 'test-task',
+				active: true,
+				cancelled: false,
+			});
+			const sendSpy = jest.spyOn(runner, 'send');
+
+			runner.sendOffers();
+
+			expect(sendSpy).toHaveBeenCalledTimes(1);
+			expect(sendSpy.mock.calls).toEqual([
+				[
+					{
+						type: 'runner:taskoffer',
+						taskType: 'test-task',
+						offerId: expect.any(String),
+						validFor: expect.any(Number),
+					},
+				],
+			]);
+		});
+
+		it('should delete stale offers and send new ones', () => {
+			runner = newTestRunner({
+				taskType: 'test-task',
+				maxConcurrency: 2,
+			});
+			runner.onMessage({
+				type: 'broker:runnerregistered',
+			});
+
+			const sendSpy = jest.spyOn(runner, 'send');
+
+			runner.sendOffers();
+			expect(sendSpy).toHaveBeenCalledTimes(2);
+			sendSpy.mockClear();
+
+			jest.advanceTimersByTime(6000);
+			runner.sendOffers();
+			expect(sendSpy).toHaveBeenCalledTimes(2);
+		});
+	});
+
 	describe('taskCancelled', () => {
 		it('should reject pending requests when task is cancelled', () => {
-			const runner = new TestRunner({
-				taskType: 'test-task',
-				maxConcurrency: 5,
-				idleTimeout: 60,
-				grantToken: 'test-token',
-				maxPayloadSize: 1024,
-				taskBrokerUri: 'http://localhost:8080',
-				timezone: 'America/New_York',
-				taskTimeout: 60,
-				healthcheckServer: {
-					enabled: false,
-					host: 'localhost',
-					port: 8081,
-				},
-			});
+			const runner = newTestRunner();
 
 			const taskId = 'test-task';
 			runner.runningTasks.set(taskId, {

packages/@n8n/task-runner/src/task-runner.ts

@@ -174,9 +174,11 @@ export abstract class TaskRunner extends EventEmitter {
 	sendOffers() {
 		this.deleteStaleOffers();
 
-		const offersToSend =
-			this.maxConcurrency -
-			(Object.values(this.openOffers).length + Object.values(this.runningTasks).length);
+		if (!this.canSendOffers) {
+			return;
+		}
+
+		const offersToSend = this.maxConcurrency - (this.openOffers.size + this.runningTasks.size);
 
 		for (let i = 0; i < offersToSend; i++) {
 			// Add a bit of randomness so that not all offers expire at the same time
@@ -255,11 +257,12 @@ export abstract class TaskRunner extends EventEmitter {
 	}
 
 	hasOpenTasks() {
-		return Object.values(this.runningTasks).length < this.maxConcurrency;
+		return this.runningTasks.size < this.maxConcurrency;
 	}
 
 	offerAccepted(offerId: string, taskId: string) {
 		if (!this.hasOpenTasks()) {
+			this.openOffers.delete(offerId);
 			this.send({
 				type: 'runner:taskrejected',
 				taskId,
@@ -267,6 +270,7 @@ export abstract class TaskRunner extends EventEmitter {
 			});
 			return;
 		}
+
 		const offer = this.openOffers.get(offerId);
 		if (!offer) {
 			this.send({