BullMQ Elixir vs Oban Benchmark

A comprehensive, fair benchmark comparing BullMQ Elixir (Redis-backed) and Oban (PostgreSQL-backed) job queues.

Overview

This benchmark compares two popular Elixir job queue libraries with proper methodology:

Feature	BullMQ Elixir	Oban
Backend	Redis (in-memory)	PostgreSQL/MySQL/SQLite
Persistence	Redis persistence (RDB/AOF)	ACID compliant
Transactions	No	Yes (database transactions)
Architecture	Event-driven, Lua scripts	Polling-based, SQL queries

Benchmark Methodology

• PostgreSQL pool_size: 150 - Exceeds concurrency to avoid connection bottlenecks
• BullMQ Redis pool_size: matches concurrency - Fair comparison without connection starvation
• Multiple runs with full statistics - Mean, median, std-dev, min, max, P95, P99
• Realistic throughput validation - Numbers are validated against theoretical limits
• Sustained workload option - Test performance over minutes, not just seconds

Prerequisites

• Elixir >= 1.15
• Redis running on localhost:6379
• PostgreSQL running on localhost:5432

Quick Start

# Clone the repository
git clone https://github.com/taskforcesh/bullmq-elixir-bench.git
cd bullmq-elixir-bench/bullmq_oban_bench

# Install dependencies and set up database
mix setup

# Run the quick benchmark (sanity check)
mix bench.quick

# Run the full comparison benchmark
mix bench.compare

Running Benchmarks

Quick Sanity Check

mix bench.quick

Runs a fast benchmark with minimal job counts to verify setup is working.

Full Comparison

mix bench.compare

Runs comprehensive tests including:

• Single job insertion
• Bulk job insertion
• Job processing (simulated I/O)
• CPU-intensive processing

Bulk Insert Analysis

mix bench.bulk

Tests bulk insertion at various job counts to analyze scaling.

Custom Options

# Larger job counts
mix bench.compare --jobs 50000 --process-jobs 10000

# Different concurrency
mix bench.compare --concurrency 200

# More runs for statistical significance
mix bench.compare --runs 5

# Sustained workload test (60 seconds)
mix bench.compare --sustained-duration 60

# Run specific test categories
mix bench.compare --only processing
mix bench.compare --only pure-overhead

# All options
mix bench.compare \
  --jobs 20000 \
  --process-jobs 10000 \
  --concurrency 100 \
  --job-duration 10 \
  --runs 5 \
  --sustained-duration 60

Options

Option	Default	Description
--jobs	10000	Number of jobs for insertion tests
--process-jobs	50000	Number of jobs for processing tests
--concurrency	100	Worker concurrency level
--job-duration	10	Simulated job duration in ms
--runs	5	Number of benchmark runs (full statistics collected)
--sustained-duration	disabled	Run sustained workload test for N seconds
--only	all	Run only specific tests (insert, processing, pure-overhead)

Tests Performed

1. Single Job Insertion

Measures the throughput of inserting jobs one at a time sequentially.

• BullMQ: Queue.add/4
• Oban: Oban.insert!/1

1b. Concurrent Single Job Insertion

Measures throughput with multiple concurrent inserters (concurrency=10).

2. Bulk Job Insertion

Measures the throughput of inserting jobs in batches of 1000.

• BullMQ: Queue.add_bulk/3
• Oban: Oban.insert_all/1

2b. Concurrent Bulk Job Insertion

Measures bulk throughput with multiple concurrent inserters.

3. Job Processing (10ms simulated work)

Measures job processing throughput with simulated I/O work.

• Tests with both 10 and 100 workers
• Theoretical max: workers × (1000ms / job_duration) jobs/sec
• With 100 workers @ 10ms: theoretical max = 10,000 jobs/sec

4. CPU-Bound Work

Measures job processing throughput with CPU-bound work (1000 sin/cos calculations).

5. Pure Queue Overhead

Measures raw queue throughput with minimal work (just counter increment). This shows the upper bound of what each queue can handle.

6. Sustained Workload (optional)

Tests performance under continuous load for a configurable duration. Use --sustained-duration N to enable (N = seconds).

Environment Configuration

Configure via environment variables:

# PostgreSQL
export POSTGRES_DB=bullmq_oban_bench_dev
export POSTGRES_USER=postgres
export POSTGRES_PASSWORD=postgres
export POSTGRES_HOST=localhost
export POSTGRES_PORT=5432

# Redis
export REDIS_HOST=localhost
export REDIS_PORT=6379

Sample Output

╔═══════════════════════════════════════════════════════════════════════════════╗
║                         BENCHMARK SUMMARY                                     ║
║                  (Statistics from 5 runs per test)                            ║
╚═══════════════════════════════════════════════════════════════════════════════╝

┌─────────────────────────────────┬───────────────────┬───────────────────┬────────────────┐
│ Test                            │ BullMQ (Redis)    │ Oban (PostgreSQL) │ Difference     │
├─────────────────────────────────┼───────────────────┼───────────────────┼────────────────┤
│ Single Job Insert (5000)        │ 4.4K jobs/sec     │ 2.1K jobs/sec     │ +116%          │
│ Concurrent Insert (5000, c=10)  │ 18.5K jobs/sec    │ 9.4K jobs/sec     │ +96%           │
│ Bulk Insert (5000)              │ 37.5K jobs/sec    │ 35.9K jobs/sec    │ +4.5%          │
│ Concurrent Bulk (5000, c=10)    │ 40.0K jobs/sec    │ 41.2K jobs/sec    │ -2.9%          │
│ 10ms work (5000, w=10)          │ 866 jobs/sec      │ 500 jobs/sec      │ +73%           │
│ 10ms work (5000, w=100)         │ 8.2K jobs/sec     │ 3.4K jobs/sec     │ +140%          │
│ CPU work (5000, w=100)          │ 24.5K jobs/sec    │ 4.0K jobs/sec     │ +512%          │
│ Pure overhead (5000, w=100)     │ 24.4K jobs/sec    │ 4.3K jobs/sec     │ +466%          │
└─────────────────────────────────┴───────────────────┴───────────────────┴────────────────┘

DETAILED STATISTICS for 10ms work (100 workers):
┌────────────┬───────────────────────┬───────────────────────┐
│ Metric     │ BullMQ                │ Oban                  │
├────────────┼───────────────────────┼───────────────────────┤
│ Mean       │ 8.2K                  │ 3.4K                  │
│ Median     │ 8.2K                  │ 3.4K                  │
│ Std Dev    │ 6.6                   │ 962.2                 │
│ Min        │ 8.2K                  │ 2.7K                  │
│ Max        │ 8.2K                  │ 4.1K                  │
│ P95        │ 8.2K                  │ 4.0K                  │
│ P99        │ 8.2K                  │ 4.1K                  │
└────────────┴───────────────────────┴───────────────────────┘

Notes:
• For 10ms work tests, theoretical max with 100 workers: 10,000 jobs/sec
• BullMQ achieves ~82% of theoretical max, Oban achieves ~34%
• Bulk insert is nearly identical - PostgreSQL multi-row INSERT is highly optimized

Understanding Throughput Limits

For job processing tests with simulated work:

• Theoretical maximum = workers × (1000ms / job_duration_ms)
• With 100 workers @ 10ms work: max = 100 × 100 = 10,000 jobs/sec

Results exceeding this would indicate a timing bug. Both libraries should approach but not exceed this limit.

Understanding the Results

• Positive difference: BullMQ is faster
• Negative difference: Oban is faster

Key Observations

1. Single/Concurrent Insertion: BullMQ is ~2x faster due to Redis in-memory operations vs PostgreSQL disk I/O.

2. Bulk Operations: Nearly identical performance! PostgreSQL's multi-row INSERT is highly optimized. For bulk inserts, Oban may even be slightly faster due to a single SQL statement vs multiple Redis commands.

3. Processing with I/O Work: BullMQ achieves ~82% of theoretical max while Oban achieves ~34%. The difference comes from BullMQ's poll-free architecture (blocking Redis commands) vs Oban's polling approach.

4. Pure Overhead: When jobs do minimal work, BullMQ can process 24K+ jobs/sec vs Oban's 4-5K. This represents the upper bound of each queue's throughput.

Configuration Matters

These benchmarks use carefully tuned configurations:

• PostgreSQL pool_size: 150 - Prevents connection contention with 100 workers
• BullMQ pool_size: 100 - Matches concurrency to avoid Redis connection bottlenecks

With default pool sizes (e.g., pool_size: 10), both libraries would show artificially lower performance due to connection starvation.

When to Choose What

Consideration	BullMQ (Redis)	Oban (PostgreSQL)
Speed	2-5x faster for queue operations	Sufficient for most use cases
Bulk Insert	~Same performance	~Same performance
Durability	Depends on Redis config (RDB/AOF)	ACID compliant by default
Transactions	Separate from app DB	Same DB as your app
Complexity	Requires Redis infrastructure	Uses existing PostgreSQL
Backups	Separate backup strategy	Backed up with app data
Ecosystem	Multi-language support (Node, Python, Elixir, PHP)	Elixir-only

Sustained Workload Testing

For production-realistic benchmarks, use the sustained workload option:

# Run for 60 seconds of continuous load
mix bench.compare --sustained-duration 60

# Run for 5 minutes
mix bench.compare --sustained-duration 300

This continuously enqueues and processes jobs for the specified duration, providing a more realistic picture of performance under sustained load.

Benchmark Methodology

Addressing Common Concerns

1. Connection pool sizing: PostgreSQL pool_size is set to 150 (exceeds 100 workers) to avoid connection contention. BullMQ's Redis pool_size is set to match concurrency.

2. Statistical rigor: Each test runs multiple times with full statistics (mean, median, std-dev, min, max, P95, P99) - not cherry-picked best results.

3. Theoretical validation: Processing benchmarks are validated against theoretical limits. With 100 workers @ 10ms work, max = 10,000 jobs/sec. Results exceeding this would indicate bugs.

4. Concurrent insertion: Benchmark includes concurrent insertion tests (not just sequential) to simulate realistic multi-producer scenarios.

5. Sustained workloads: Optional --sustained-duration flag allows testing over minutes/hours instead of just seconds.

6. Timing accuracy: Timing starts BEFORE workers begin processing, not after warm-up, ensuring accurate measurement.

Docker Setup (Optional)

If you don't have Redis and PostgreSQL installed locally:

# Start Redis
docker run -d --name redis -p 6379:6379 redis:alpine

# Start PostgreSQL
docker run -d --name postgres \
  -e POSTGRES_PASSWORD=postgres \
  -p 5432:5432 \
  postgres:15-alpine

Project Structure

bullmq_oban_bench/
├── bench/
│   ├── comparison_bench.exs   # Full comparison benchmark
│   ├── quick_bench.exs        # Quick sanity check
│   └── bulk_bench.exs         # Bulk insert analysis
├── config/
│   ├── config.exs             # Main configuration
│   ├── dev.exs                # Development config
│   ├── test.exs               # Test config
│   └── prod.exs               # Production config
├── lib/
│   └── bullmq_oban_bench/
│       ├── application.ex     # Application supervisor
│       ├── repo.ex            # Ecto Repo for Oban
│       └── oban_worker.ex     # Oban benchmark worker
├── priv/
│   └── repo/
│       └── migrations/        # Database migrations
├── mix.exs                    # Project definition
└── README.md                  # This file

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Related Links

• BullMQ Documentation
• BullMQ Elixir Package
• Oban Documentation
• BullMQ vs Oban Benchmark Article

License

MIT License - See LICENSE for details.