Remove Dependency

Remove failed children from parent dependencies to allow parent completion

In some situations, you may have a parent job and need to remove the relationship when one of its children fails. The removeDependencyOnFailure option allows the parent to complete without waiting for failed children.

How It Works

The removeDependencyOnFailure option makes sure that when a job fails, the dependency is removed from the parent, so the parent will complete without waiting for the failed children.

As soon as a child with this option fails, the parent job will be moved to a waiting state only if there are no more pending children.

Basic Usage

import { FlowProducer } from 'bullmq';

const flow = new FlowProducer({ connection });

const originalTree = await flow.add({
  name: 'root-job',
  queueName: 'topQueueName',
  data: {},
  children: [
    {
      name: 'child-job',
      data: { idx: 0, foo: 'bar' },
      queueName: 'childrenQueueName',
      opts: { removeDependencyOnFailure: true },
      children: [
        {
          name: 'grandchild-1',
          data: { idx: 1, foo: 'bah' },
          queueName: 'grandChildrenQueueName',
        },
        {
          name: 'grandchild-2',
          data: { idx: 2, foo: 'baz' },
          queueName: 'grandChildrenQueueName',
        },
      ],
    },
    {
      name: 'another-child',
      data: { idx: 3, foo: 'foo' },
      queueName: 'childrenQueueName',
    },
  ],
});

Behavior

When a child job with removeDependencyOnFailure: true fails:

1. The dependency relationship is removed from the parent
2. The failed child is no longer tracked in the parent’s dependencies
3. The parent can complete without waiting for this child
4. If this was the last pending child, the parent moves to waiting state

1. Child job fails

   A child with removeDependencyOnFailure: true encounters an error and moves to failed state.

2. Dependency removed

   BullMQ removes this child from the parent’s dependency list.

3. Check remaining dependencies

   If there are still other pending children, the parent continues waiting.

4. Parent becomes active

   Once all other children complete, the parent moves to waiting state and can be processed.

Example with Multiple Children

const flow = await flowProducer.add({
  name: 'data-processing',
  queueName: 'processing',
  data: { batchId: '123' },
  children: [
    {
      name: 'required-validation',
      queueName: 'validation',
      data: { type: 'required' },
      // No removeDependencyOnFailure - this MUST succeed
    },
    {
      name: 'optional-enrichment',
      queueName: 'enrichment',
      data: { type: 'optional' },
      opts: { removeDependencyOnFailure: true },
      // Can fail without blocking parent
    },
    {
      name: 'best-effort-analysis',
      queueName: 'analysis',
      data: { type: 'best-effort' },
      opts: { removeDependencyOnFailure: true },
      // Can fail without blocking parent
    },
  ],
});

In this example:

• If optional-enrichment or best-effort-analysis fails, they are removed from dependencies
• The parent will process once required-validation completes
• If required-validation fails, the parent will not process (default behavior)

Use Cases

Optional Data Enrichment

Process data with optional enrichment steps that can fail without affecting the core workflow:

const flow = await flowProducer.add({
  name: 'process-user-data',
  queueName: 'user-processing',
  data: { userId: '12345' },
  children: [
    {
      name: 'validate-user',
      queueName: 'validation',
      data: {},
      // Required - must succeed
    },
    {
      name: 'enrich-with-social',
      queueName: 'enrichment',
      data: { source: 'social-media' },
      opts: { removeDependencyOnFailure: true },
      // Optional - can fail
    },
    {
      name: 'enrich-with-demographics',
      queueName: 'enrichment',
      data: { source: 'demographics-api' },
      opts: { removeDependencyOnFailure: true },
      // Optional - can fail
    },
  ],
});

const userWorker = new Worker('user-processing', async job => {
  // Process user data with whatever enrichment succeeded
  const childrenValues = await job.getChildrenValues();
  
  return {
    userId: job.data.userId,
    validated: true,
    enrichments: childrenValues,
  };
});

Best-Effort Notifications

Send notifications that shouldn’t block the main workflow:

const orderFlow = await flowProducer.add({
  name: 'process-order',
  queueName: 'orders',
  data: { orderId: 'ORD-123' },
  children: [
    {
      name: 'charge-payment',
      queueName: 'payments',
      data: {},
      // Required - must succeed
    },
    {
      name: 'update-inventory',
      queueName: 'inventory',
      data: {},
      // Required - must succeed
    },
    {
      name: 'send-sms-notification',
      queueName: 'notifications',
      data: { type: 'sms' },
      opts: { removeDependencyOnFailure: true },
      // Optional - SMS failure shouldn't block order
    },
    {
      name: 'send-email-receipt',
      queueName: 'notifications',
      data: { type: 'email' },
      opts: { removeDependencyOnFailure: true },
      // Optional - email failure shouldn't block order
    },
  ],
});

Analytics and Tracking

Track analytics without blocking the main business logic:

const signupFlow = await flowProducer.add({
  name: 'complete-signup',
  queueName: 'signups',
  data: { email: '[e-mail]' },
  children: [
    {
      name: 'create-account',
      queueName: 'accounts',
      data: {},
      // Required
    },
    {
      name: 'send-welcome-email',
      queueName: 'emails',
      data: {},
      // Required
    },
    {
      name: 'track-analytics',
      queueName: 'analytics',
      data: { event: 'signup' },
      opts: { removeDependencyOnFailure: true },
      // Optional - analytics failure shouldn't block signup
    },
    {
      name: 'update-crm',
      queueName: 'crm',
      data: {},
      opts: { removeDependencyOnFailure: true },
      // Optional - CRM failure shouldn't block signup
    },
  ],
});

Difference from ignoreDependencyOnFailure

removeDependencyOnFailure is similar to ignoreDependencyOnFailure, but with key differences:

removeDependencyOnFailure

• Completely removes the child from dependencies
• Failed child is not tracked
• Cannot retrieve failed child information later

ignoreDependencyOnFailure

• Keeps the child in dependencies
• Failed child is tracked as “ignored”
• Can retrieve failed child information using getIgnoredChildrenFailures()

// With removeDependencyOnFailure
const flow1 = await flowProducer.add({
  name: 'parent',
  queueName: 'queue',
  children: [
    {
      name: 'child',
      queueName: 'queue',
      opts: { removeDependencyOnFailure: true },
    },
  ],
});

// Parent processor
const worker1 = new Worker('queue', async job => {
  if (job.name === 'parent') {
    // Cannot access removed child information
    const childrenValues = await job.getChildrenValues();
    // childrenValues will not include the failed child
  }
});

// With ignoreDependencyOnFailure
const flow2 = await flowProducer.add({
  name: 'parent',
  queueName: 'queue',
  children: [
    {
      name: 'child',
      queueName: 'queue',
      opts: { ignoreDependencyOnFailure: true },
    },
  ],
});

// Parent processor
const worker2 = new Worker('queue', async job => {
  if (job.name === 'parent') {
    // Can access ignored child information
    const ignoredFailures = await job.getIgnoredChildrenFailures();
    // ignoredFailures will include the failed child
  }
});

Monitoring Removed Dependencies

You can track when dependencies are removed:

import { QueueEvents } from 'bullmq';

const queueEvents = new QueueEvents('topQueueName', { connection });

queueEvents.on('waiting', async ({ jobId }) => {
  const job = await queue.getJob(jobId);
  
  if (job.parentKey) {
    console.log(`Child ${jobId} completed, parent can now process`);
  }
});

queueEvents.on('failed', async ({ jobId, failedReason }) => {
  const job = await queue.getJob(jobId);
  const opts = job.opts;
  
  if (opts.removeDependencyOnFailure) {
    console.log(`Child ${jobId} failed but was removed from parent dependencies`);
  }
});

Parent Processor Example

Handle the case where some children were removed:

import { Worker } from 'bullmq';

const parentWorker = new Worker('topQueueName', async job => {
  const childrenValues = await job.getChildrenValues();
  
  // Get dependency counts to see what happened
  const { processed, failed } = await job.getDependenciesCount();
  
  console.log(`Processed: ${processed}, Failed (removed): ${failed}`);
  
  // Process with whatever children succeeded
  const results = Object.values(childrenValues);
  
  if (results.length === 0) {
    return { status: 'completed', note: 'All optional children failed' };
  }
  
  return {
    status: 'completed',
    processedCount: results.length,
    data: processResults(results),
  };
});

Best Practices

Use for Optional Features

Apply to children that provide optional enhancements or features

Not for Critical Paths

Never use for children that are critical to the workflow

Log Removed Dependencies

Track when dependencies are removed for monitoring and debugging

Handle Missing Data

Parent should handle cases where optional children didn’t provide data

Use removeDependencyOnFailure carefully. The parent job will have no record of the failed child, making debugging more difficult. Consider using ignoreDependencyOnFailure if you need to track failed optional children.

For better observability, use ignoreDependencyOnFailure instead of removeDependencyOnFailure when you want to keep track of which optional children failed.

API Reference

• Add Flow API Reference
• FlowProducer API Reference
• Job Options API Reference