Why Is n8n's Execute Workflow Triggering Duplicate Executions in Queue Mode?

Hello everyone,

I’m experiencing an unexpected behavior with n8n where a parent workflow that triggers the child workflow called sendMessage via the Execute Workflow node is causing duplicate executions. Specifically, the parent workflow sends 181 items to sendMessage, but the logs show around 542 executions for the same parent execution ID, resulting in duplicate data processing.

Context

• I have a parent workflow that triggers a child workflow (named sendMessage) using the Execute Workflow node.
• The parent workflow sends 181 items to the child, so it should trigger 181 executions in sendMessage.
• Issue: Logs indicate that sendMessage is executed roughly 542 times with duplicate data and the same execution ID.

Here’s what happens:

• The trigger node “sendMessage” in the workflow “Launch_send_message” sends 181 items to the workflow “sendMessage”.
• Instead of 181 executions, there are approximately 542, with duplicates (same data, IDs, and identical information).

See the screenshots for reference:

error-launch-send-message
Capture d’écran 2025-01-28 à 19.39.41
image

In the sendMessage workflow, data is received once per item, so 181 executions are expected. However, there are about 542 executions with duplicate entries.

sendMessage
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Environment

• n8n Deployment: Docker with Docker Compose
• Execution Mode: EXECUTIONS_MODE=queue
• Setup: 1 main n8n container (handling the interface) and 6 workers (n8n-worker-X), along with n8n-webhook-X services
• Database: Postgres 16
• Queue: Redis 6
• Proxy: Traefik

What I Have Already Checked

• There are no loops or misconfigured batch splits in the parent workflow.
• All 542 executions in the logs share the same parent executionId.
• I noticed that the main container does not explicitly set N8N_DISABLE_PRODUCTION_MAIN_PROCESS=true, meaning the main process might be running the 181 items alongside the workers.
• The presence of multiple workers may be contributing to the duplicate executions.

Questions

1. Why is n8n executing the same items multiple times?
2. Are there certain environment variables such as EXECUTIONS_WORKER=queue, EXECUTIONS_WORKER_PROCESS, N8N_DISABLE_PRODUCTION_MAIN_PROCESS=true, QUEUE_HEALTH_CHECK_ACTIVE, etc., that might be misconfigured or missing?
3. Out of the various available environment variables, which ones should be used for a stable multiple-worker setup in queue mode? (See n8n Queue Mode Environment Variables Documentation)

Any suggestions or potential solutions are welcome!

If you have examples of functional docker-compose configurations in queue mode with multiple workers, I would greatly appreciate it.

Thank you for your help!

Current docker-compose.yml Configuration:

YAMLCopied
version: '3.8'

volumes:
  db_storage:
  n8n_storage:
  redis_storage:
  traefik_data:
  ollama_storage:

x-shared: &shared
  restart: always
  image: docker.n8n.io/n8nio/n8n
  environment:
    - DB_TYPE=postgresdb
    - DB_POSTGRESDB_HOST=postgres
    - DB_POSTGRESDB_PORT=5432
    - DB_POSTGRESDB_DATABASE=${POSTGRES_DB}
    - DB_POSTGRESDB_USER=${POSTGRES_NON_ROOT_USER}
    - DB_POSTGRESDB_PASSWORD=${POSTGRES_NON_ROOT_PASSWORD}
    - EXECUTIONS_MODE=queue
    - QUEUE_BULL_REDIS_HOST=redis
    - QUEUE_HEALTH_CHECK_ACTIVE=true
    - N8N_ENCRYPTION_KEY=${ENCRYPTION_KEY}
    - N8N_BASIC_AUTH_ACTIVE=true
    - N8N_BASIC_AUTH_USER=${N8N_BASIC_AUTH_USER}
    - N8N_BASIC_AUTH_PASSWORD=${N8N_BASIC_AUTH_PASSWORD}
    - N8N_HOST=n8n.exemple.fr
    - N8N_PORT=5678
    - N8N_PROTOCOL=https
    - WEBHOOK_URL=https://n8n.exemple.fr/
  links:
    - postgres
    - redis
  volumes:
    - n8n_storage:/home/node/.n8n
  depends_on:
    redis:
      condition: service_healthy
    postgres:
      condition: service_healthy

x-ollama: &service-ollama
  image: ollama/ollama:latest
  container_name: ollama
  restart: unless-stopped
  volumes:
    - ollama_storage:/root/.ollama

services:
  traefik:
    image: traefik:latest
    container_name: traefik
    networks:
      - default
    restart: unless-stopped
    command:
      - "--api=true"
      - "--api.insecure=true"
      - "--providers.docker=true"
      - "--providers.docker.exposedbydefault=false"
      - "--entrypoints.web.address=:80"
      - "--entrypoints.web.http.redirections.entryPoint.to=websecure"
      - "--entrypoints.web.http.redirections.entrypoint.scheme=https"
      - "--entrypoints.websecure.address=:443"
      - "--certificatesresolvers.mytlschallenge.acme.tlschallenge=true"
      - "--certificatesresolvers.mytlschallenge.acme.email=${SSL_EMAIL}"
      - "--certificatesresolvers.mytlschallenge.acme.storage=/letsencrypt/acme.json"
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - traefik_data:/letsencrypt
      - /var/run/docker.sock:/var/run/docker.sock:ro

  postgres:
    image: postgres:16
    restart: always
    environment:
      - POSTGRES_USER=${POSTGRES_USER}
      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
      - POSTGRES_DB=${POSTGRES_DB}
      - POSTGRES_NON_ROOT_USER=${POSTGRES_NON_ROOT_USER}
      - POSTGRES_NON_ROOT_PASSWORD=${POSTGRES_NON_ROOT_PASSWORD}
    volumes:
      - db_storage:/var/lib/postgresql/data
      - ./init-data.sh:/docker-entrypoint-initdb.d/init-data.sh
    healthcheck:
      test: ['CMD-SHELL', 'pg_isready -h localhost -U ${POSTGRES_USER} -d ${POSTGRES_DB}']
      interval: 5s
      timeout: 5s
      retries: 10

  redis:
    image: redis:6-alpine
    restart: always
    volumes:
      - redis_storage:/data
    healthcheck:
      test: ['CMD', 'redis-cli', 'ping']
      interval: 5s
      timeout: 5s
      retries: 10

  n8n:
    <<: *shared
    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.n8n.rule=Host(`n8n.exemple.fr`)"
      - "traefik.http.routers.n8n.entrypoints=websecure"
      - "traefik.http.routers.n8n.tls=true"
      - "traefik.http.routers.n8n.tls.certresolver=mytlschallenge"
    deploy:
      resources:
        limits:
          cpus: "1"

  n8n-worker-1:
    <<: *shared
    command: worker
    deploy:
      resources:
        limits:
          cpus: "1"
    depends_on:
      - n8n

  n8n-worker-2:
    <<: *shared
    command: worker
    deploy:
      resources:
        limits:
          cpus: "1"
    depends_on:
      - n8n

  n8n-worker-3:
    <<: *shared
    command: worker
    deploy:
      resources:
        limits:
          cpus: "1"
    depends_on:
      - n8n

  n8n-worker-4:
    <<: *shared
    command: worker
    deploy:
      resources:
        limits:
          cpus: "1"
    depends_on:
      - n8n

  n8n-worker-5:
    <<: *shared
    command: worker
    deploy:
      resources:
        limits:
          cpus: "1"
    depends_on:
      - n8n

  n8n-worker-6:
    <<: *shared
    command: worker
    deploy:
      resources:
        limits:
          cpus: "1"
    depends_on:
      - n8n

  n8n-webhook-1:
    <<: *shared
    command: webhook
    deploy:
      resources:
        limits:
          cpus: "0.5"
    depends_on:
      - n8n

  n8n-webhook-2:
    <<: *shared
    command: webhook
    deploy:
      resources:
        limits:
          cpus: "0.5"
    depends_on:
      - n8n

  ollama-cpu:
    <<: *service-ollama