avoid some unnecessary work

src/v3/lib/queue.ts

@@ -137,9 +137,10 @@ export class Queue<
 	#willRun = false
 	#sleepTimeout: NodeJS.Timeout | null = null
 
-	#drain(): void | Promise<void> {
+	/** @returns `true` if it managed to drain the queue */
+	#drain(): boolean | Promise<boolean> {
 		return this.storage.startNextTask(this.id, (result) => {
-			if (!result) return
+			if (!result) return true
 
 			const [task, steps, hasNext] = result
 			const job = this.jobs[task.job]
@@ -153,8 +154,12 @@ export class Queue<
 				this.#loop()
 			})
 
-			if (hasNext && this.#running.size < this.parallel) return this.#drain()
-		}) as void | Promise<void>
+			if (!hasNext) return true
+			if (this.#running.size >= this.parallel) return false
+			if (this.#closed) return false
+
+			return this.#drain()
+		}) as boolean | Promise<boolean>
 	}
 
 	// TODO: should this be public? Might be useful for cases where multiple queue workers are writing to the same storage, and we don't want to poll and would rather have a manual trigger.
@@ -168,8 +173,9 @@ export class Queue<
 		}
 		setImmediate(async () => {
 			if (this.#closed) return
-			await this.#drain()
+			const drained = await this.#drain()
 			this.#willRun = false
+			if (!drained || this.#closed) return // can't do anything else, we're at the limit of `parallel` jobs
 			setImmediate(() => {
 				if (this.#willRun || this.#closed) return
 				this.storage.nextFutureTask(this.id, (result) => {