fix: Clear the timer for task timeout after the task has completed

src/promise-pool-executor.ts

@@ -543,21 +543,27 @@ export class PromisePoolExecutor<T, R> implements UsesConcurrency, Stoppable, St
       return this.handler(item, index, this)
     }
 
+    const [timer, canceller] = this.createTaskTimeout(item)
     return Promise.race([
       this.handler(item, index, this),
-      this.createTaskTimeout(item)
-    ])
+      timer(),
+    ]).finally(canceller)
   }
 
   /**
-   * Returns a promise that times-out after the configured task timeout.
+   * Returns a tuple of a timer function and a canceller function that
+   * times-out after the configured task timeout.
    */
-  private async createTaskTimeout (item: T): Promise<void> {
-    return new Promise<void>((_resolve, reject) => {
-      setTimeout(() => {
-        reject(new PromisePoolError(`Promise in pool timed out after ${this.taskTimeout() as number}ms`, item))
-      }, this.taskTimeout())
-    })
+  private createTaskTimeout (item: T): [() => Promise<void>, () => void] {
+    let timerId: ReturnType<typeof setTimeout> | undefined
+    const timer: () => Promise<void> = async () =>
+      new Promise<void>((_resolve, reject) => {
+        timerId = setTimeout(() => {
+          reject(new PromisePoolError(`Promise in pool timed out after ${this.taskTimeout() as number}ms`, item))
+        }, this.taskTimeout())
+      })
+    const canceller: () => void = () => clearTimeout(timerId)
+    return [timer, canceller]
   }
 
   /**

test/promise-pool.js

@@ -630,19 +630,20 @@ test('useCorrespondingResults defaults results to notRun symbol', async () => {
 
 test('can timeout long-running handlers', async () => {
   const timers = [1, 2, 3, 4]
+  const leeway = 5
 
   const { results, errors } = await PromisePool
     .withTaskTimeout(10)
     .for(timers)
     .process(async (timer) => {
-      const computed = 10 * timer
+      const computed = 10 * timer - leeway
       await pause(computed)
 
       return computed
     })
 
   // only the first item resolves
-  expect(results).toEqual([10])
+  expect(results).toEqual([5])
 
   // items 2, 3, and 4 time out
   expect(errors.length).toEqual(3)