Cancelling Jobs

The job cancellation feature allows you to gracefully cancel jobs that are currently being processed by a worker. This is implemented using the standard AbortController and AbortSignal APIs.

How It Works

When a worker processes a job, it can receive an optional AbortSignal as the third parameter in the processor function. This signal can be used to detect when a job has been cancelled and perform cleanup operations.

import { Worker } from 'bullmq';

const worker = new Worker('myQueue', async (job, token, signal) => {
  // The signal parameter is optional and provides cancellation support
  // Your job processing logic here
});

Cancelling Jobs

The Worker class provides methods to cancel jobs:

// Cancel a specific job by ID
const cancelled = worker.cancelJob('job-id-123');
console.log('Job cancelled:', cancelled); // true if job was active, false otherwise

// Cancel with a reason (useful for debugging)
worker.cancelJob('job-id-456', 'User requested cancellation');

// Cancel all active jobs
worker.cancelAllJobs();

// Cancel all with a reason
worker.cancelAllJobs('System shutdown');

// Get list of active jobs from queue
const activeJobs = await queue.getActive();
console.log(
  'Active jobs:',
  activeJobs.map(j => j.id),
);

Cancellation Reasons

When you provide a cancellation reason, it's passed to the AbortController.abort(reason) method and can be accessed via signal.reason:

const worker = new Worker('myQueue', async (job, token, signal) => {
  return new Promise((resolve, reject) => {
    signal?.addEventListener('abort', () => {
      // Access the cancellation reason
      const reason = signal.reason || 'No reason provided';
      console.log(`Job ${job.id} cancelled: ${reason}`);

      reject(new Error(`Cancelled: ${reason}`));
    });

    // Your processing logic
  });
});

// Later, cancel with a descriptive reason
worker.cancelJob(job.id, 'Resource limit exceeded');

Handling Cancellation (Recommended Pattern)

The event-based approach is the recommended pattern as it provides immediate response to cancellation:

import { Worker } from 'bullmq';

const worker = new Worker('myQueue', async (job, token, signal) => {
  return new Promise((resolve, reject) => {
    // Listen for abort event
    signal?.addEventListener('abort', () => {
      console.log(`Job ${job.id} cancellation requested`);

      // Clean up resources
      clearInterval(interval);

      // Reject with error
      reject(new Error('Job was cancelled'));
    });

    // Your processing logic
    const interval = setInterval(() => {
      // Do work
      processNextItem();
    }, 100);
  });
});

Why Event-Based?

• ✅ Immediate response - No polling delay
• ✅ More efficient - No CPU wasted checking in loops
• ✅ Cleaner code - Separation of concerns
• ✅ Standard pattern - Matches Web APIs like fetch()

Using with Native APIs (Recommended)

Many Web APIs natively support AbortSignal. The signal is composable - you can pass it to APIs and still listen to it yourself:

const worker = new Worker('fetchQueue', async (job, token, signal) => {
  return new Promise(async (resolve, reject) => {
    // Set up abort listener - handles cancellation for the job
    signal?.addEventListener('abort', () => {
      reject(new Error('Job was cancelled'));
    });

    // Pass the SAME signal to fetch - it will abort the network request
    const response = await fetch(job.data.url, {
      signal, // ✅ Cancels the HTTP request at network level
      method: 'GET',
      headers: job.data.headers,
    });

    const data = await response.json();
    resolve(data);
  });
});

Why this pattern is better:

• ✅ Simpler - One abort listener handles everything
• ✅ Composable - Signal passed to fetch() AND listened to in job
• ✅ The HTTP request is truly cancelled at the network level
• ✅ The job is properly marked as failed when cancelled
• ✅ No complex error checking needed

APIs That Support AbortSignal

Many modern APIs accept signal directly:

• fetch(url, { signal }) - HTTP requests
• addEventListener(event, handler, { signal }) - Auto-removes listener on abort
• Many database clients (Postgres, MongoDB drivers)
• File system operations in newer Node.js APIs

Cancelling Custom Operations

For operations that don't natively support AbortSignal, implement proper cleanup:

const worker = new Worker('customQueue', async (job, token, signal) => {
  // Start your operation
  const operation = startLongRunningOperation(job.data);

  // Set up cancellation handler that actually stops the operation
  signal?.addEventListener('abort', () => {
    operation.cancel(); // ✅ Actually stops the work
  });

  try {
    const result = await operation.promise;
    return result;
  } catch (error) {
    if (signal?.aborted) {
      throw new Error('Operation cancelled');
    }
    throw error;
  }
});

Async Cleanup on Cancellation

Perform cleanup operations before rejecting the promise:

const worker = new Worker('dbQueue', async (job, token, signal) => {
  // Acquire resources
  const db = await connectToDatabase();
  const cache = await connectToCache();

  return new Promise(async (resolve, reject) => {
    // Set up cleanup handler
    signal?.addEventListener('abort', async () => {
      try {
        console.log('Cleaning up resources...');

        // Close connections gracefully
        await db.close();
        await cache.disconnect();

        console.log('Cleanup complete');
        reject(new Error('Cancelled after cleanup'));
      } catch (cleanupError) {
        console.error('Cleanup failed:', cleanupError);
        reject(new Error('Cleanup failed during cancellation'));
      }
    });

    try {
      // Do your work
      const result = await processWithDatabase(db, job.data);
      await cache.set(`job:${job.id}`, result);
      resolve(result);
    } catch (error) {
      // Cleanup on error too
      await db.close();
      await cache.disconnect();
      throw error;
    }
  });
});

Alternative: Polling Pattern

You can also check signal.aborted periodically (less efficient but simpler for some use cases):

const worker = new Worker('batchQueue', async (job, token, signal) => {
  const items = job.data.items;
  const results = [];

  for (let i = 0; i < items.length; i++) {
    // Check if job has been cancelled
    if (signal?.aborted) {
      throw new Error(`Cancelled after processing ${i} items`);
    }

    const result = await processItem(items[i]);
    results.push(result);

    // Update progress
    await job.updateProgress(((i + 1) / items.length) * 100);
  }

  return { results, total: results.length };
});

Job State After Cancellation

With Regular Error (Will Retry)

When you throw a regular Error upon cancellation:

• Job state: Moves to failed
• Retries: Job WILL be retried if attempts remain
• Use case: When you want the job to be retried later

const worker = new Worker('retryQueue', async (job, token, signal) => {
  return new Promise((resolve, reject) => {
    signal?.addEventListener('abort', () => {
      // Regular Error - job will retry if attempts remain
      reject(new Error('Cancelled, will retry'));
    });

    // Your work...
  });
});

// Set attempts when adding jobs
await queue.add('task', data, { attempts: 3 });

With UnrecoverableError (No Retry)

When you throw an UnrecoverableError:

• Job state: Moves to failed
• Retries: Job will NOT be retried
• Use case: When cancellation should be permanent

import { Worker, UnrecoverableError } from 'bullmq';

const worker = new Worker('noRetryQueue', async (job, token, signal) => {
  return new Promise((resolve, reject) => {
    signal?.addEventListener('abort', () => {
      // UnrecoverableError - no retries
      reject(new UnrecoverableError('Cancelled permanently'));
    });

    // Your work...
  });
});

Handling Lock Renewal Failures

When a worker loses its lock on a job (due to network issues, Redis problems, or long-running operations), you can gracefully handle this situation using the lockRenewalFailed event:

const worker = new Worker(
  'myQueue',
  async (job, token, signal) => {
    return new Promise(async (resolve, reject) => {
      signal?.addEventListener('abort', async () => {
        console.log('Job cancelled - cleaning up resources');
        await cleanupResources();
        reject(new Error('Job cancelled'));
      });

      // Your work...
    });
  },
  { connection },
);

// Cancel jobs when lock renewal fails
worker.on('lockRenewalFailed', (jobIds: string[]) => {
  console.log('Lock renewal failed for jobs:', jobIds);
  jobIds.forEach(jobId => worker.cancelJob(jobId));
});

WARNING

Important: When a worker loses the lock on a job, it cannot move that job to the failed state (as it no longer owns the lock). Instead:

1. The cancelJob() aborts the signal, allowing the processor to clean up resources
2. The job remains in active state temporarily
3. BullMQ's stalled job checker will detect the job and move it back to waiting
4. Another worker (or the same worker) will pick it up and retry

This is the correct and intended behavior - trust BullMQ's stalled job mechanism to handle lost locks.

Why This Pattern Works

• ✅ Immediate cleanup: The processor detects signal.aborted and can release resources
• ✅ No wasted work: The processor stops processing when it loses the lock
• ✅ Automatic recovery: The stalled job checker moves the job back to waiting
• ✅ No data loss: The job will be retried according to its attempts setting
• ✅ Works with existing infrastructure: Uses BullMQ's built-in stalled job handling

Multi-Phase Work with Cancellation

Check cancellation at strategic points in multi-phase operations:

const worker = new Worker('multiPhaseQueue', async (job, token, signal) => {
  return new Promise(async (resolve, reject) => {
    signal?.addEventListener('abort', () => {
      reject(new Error('Cancelled'));
    });

    try {
      // Phase 1: Download
      if (signal?.aborted) throw new Error('Cancelled before download');
      const data = await downloadData(job.data.url);
      await job.updateProgress(33);

      // Phase 2: Process
      if (signal?.aborted) throw new Error('Cancelled before processing');
      const processed = await processData(data);
      await job.updateProgress(66);

      // Phase 3: Upload
      if (signal?.aborted) throw new Error('Cancelled before upload');
      const result = await uploadResults(processed);
      await job.updateProgress(100);

      resolve(result);
    } catch (error) {
      reject(error);
    }
  });
});

Backward Compatibility

The signal parameter is optional. Existing processors that don't use it will continue to work normally:

// Old processor - still works
const worker = new Worker('myQueue', async job => {
  return await processJob(job);
});

// New processor - with cancellation support
const worker = new Worker('myQueue', async (job, token, signal) => {
  // Can now handle cancellation
});

INFO

The cancellation feature is fully backward compatible. You only need to add signal handling when you want cancellation support.

Best Practices

1. Use event-based cancellation for immediate response
2. Clean up resources in the abort handler
3. Use UnrecoverableError when cancellation should be permanent
4. Combine with timeouts for better control
5. Check signal.aborted at strategic points in long operations
6. Handle cleanup errors gracefully to avoid leaving resources open

Read more:

• 💡 Worker API Reference
• 💡 AbortController MDN
• 💡 AbortSignal MDN