fix(jobprocessor): ensure set timeout is only called once for each job in the queue

as discussed in agenda/agenda#1146

Author: simllll

src/Job.ts

@@ -21,6 +21,10 @@ export class Job<DATA = unknown | void> {
 	 */
 	canceled: Error | undefined;
 
+	/** internal variable to ensure a job does not set unlimited numbers of setTimeouts if the job is not processed
+	 * immediately */
+	gotTimerToExecute: boolean;
+
 	/**
 	 * creates a new job object
 	 * @param agenda
@@ -33,7 +37,7 @@ export class Job<DATA = unknown | void> {
 			name: string;
 			type: 'normal' | 'single';
 		},
-		byJobProcessor?
+		byJobProcessor?: boolean
 	);
 	constructor(
 		agenda: Agenda,
@@ -42,7 +46,7 @@ export class Job<DATA = unknown | void> {
 			type: 'normal' | 'single';
 			data: DATA;
 		},
-		byJobProcessor?
+		byJobProcessor?: boolean
 	);
 	constructor(
 		readonly agenda: Agenda,

src/JobProcessingQueue.ts

@@ -117,6 +117,7 @@ export class JobProcessingQueue {
 				(!status || !def.concurrency || status.running < def.concurrency)
 			) {
 				if (!this._queue[i].attrs.nextRunAt) {
+					// eslint-disable-next-line no-console
 					console.log('this._queue[i]', this._queue[i].attrs);
 					throw new Error('no nextRunAt date');
 				}

src/JobProcessor.ts

@@ -385,7 +385,8 @@ export class JobProcessor {
 				'[%s:%s] there is a job to process (priority = %d)',
 				job.attrs.name,
 				job.attrs._id,
-				job.attrs.priority
+				job.attrs.priority,
+				job.gotTimerToExecute
 			);
 
 			this.jobQueue.remove(job);
@@ -430,13 +431,17 @@ export class JobProcessor {
 					);
 					// re add to queue (puts it at the right position in the queue)
 					this.jobQueue.insert(job);
-					setTimeout(
-						() => {
-							this.jobProcessing();
-						},
-						runIn > MAX_SAFE_32BIT_INTEGER ? MAX_SAFE_32BIT_INTEGER : runIn
-					); // check if runIn is higher than unsined 32 bit int, if so, use this time to recheck,
-					// because setTimeout will run in an overflow otherwise and reprocesses immediately
+					// ensure every job gets a timer to run at the near future time (but also ensure this time is set only once)
+					if (!job.gotTimerToExecute) {
+						job.gotTimerToExecute = true;
+						setTimeout(
+							() => {
+								this.jobProcessing();
+							},
+							runIn > MAX_SAFE_32BIT_INTEGER ? MAX_SAFE_32BIT_INTEGER : runIn
+						); // check if runIn is higher than unsined 32 bit int, if so, use this time to recheck,
+						// because setTimeout will run in an overflow otherwise and reprocesses immediately
+					}
 				}
 			}