Queues API Reference

Producer: Send Messages

// Basic send
await env.MY_QUEUE.send({ url: request.url, timestamp: Date.now() });

// Options: delay (max 43200s), contentType (json|text|bytes|v8)
await env.MY_QUEUE.send(message, { delaySeconds: 600 });
await env.MY_QUEUE.send(message, { delaySeconds: 0 }); // Override queue default

// Batch (up to 100 msgs or 256 KB)
await env.MY_QUEUE.sendBatch([
  { body: 'msg1' },
  { body: 'msg2' },
  { body: 'msg3', options: { delaySeconds: 300 } }
]);

// Non-blocking with ctx.waitUntil - send continues after response
ctx.waitUntil(env.MY_QUEUE.send({ data: 'async' }));

// Background tasks in queue consumer

  async queue(batch: MessageBatch, env: Env, ctx: ExecutionContext): Promise<void> {
    for (const msg of batch.messages) {
      await processMessage(msg.body);
      
      // Fire-and-forget analytics (doesn't block ack)
      ctx.waitUntil(
        env.ANALYTICS_QUEUE.send({ messageId: msg.id, processedAt: Date.now() })
      );
      
      msg.ack();
    }
  }
};

Consumer: Push-based (Worker)

// Type-safe handler with ExportedHandler
interface Env {
  MY_QUEUE: Queue;
  DB: D1Database;
}

  async queue(batch: MessageBatch, env: Env, ctx: ExecutionContext): Promise<void> {
    // batch.queue, batch.messages.length
    for (const msg of batch.messages) {
      // msg.id, msg.body, msg.timestamp, msg.attempts
      try {
        await processMessage(msg.body);
        msg.ack();
      } catch (error) {
        msg.retry({ delaySeconds: 600 });
      }
    }
  }
} satisfies ExportedHandler;

CRITICAL WARNINGS:

1. Messages not explicitly ack'd or retry'd will auto-retry indefinitely until max_retries is reached. Always call msg.ack() or msg.retry() for each message.

2. Throwing uncaught errors retries the ENTIRE batch, not just the failed message. Always wrap individual message processing in try/catch and call msg.retry() explicitly per message.

// ❌ BAD: Uncaught error retries entire batch
async queue(batch: MessageBatch): Promise<void> {
  for (const msg of batch.messages) {
    await riskyOperation(msg.body); // If this throws, entire batch retries
    msg.ack();
  }
}

// ✅ GOOD: Catch per message, handle individually
async queue(batch: MessageBatch): Promise<void> {
  for (const msg of batch.messages) {
    try {
      await riskyOperation(msg.body);
      msg.ack();
    } catch (error) {
      msg.retry({ delaySeconds: 60 });
    }
  }
}

Ack/Retry Precedence Rules

1. Per-message calls take precedence: If you call both msg.ack() and msg.retry(), last call wins
2. Batch calls don't override: batch.ackAll() only affects messages without explicit ack/retry
3. No action = automatic retry: Messages with no explicit action retry with configured delay

async queue(batch: MessageBatch): Promise<void> {
  for (const msg of batch.messages) {
    msg.ack();        // Message marked for ack
    msg.retry();      // Overrides ack - message will retry
  }
  
  batch.ackAll();     // Only affects messages not explicitly handled above
}

Batch Operations

// Acknowledge entire batch
try {
  await bulkProcess(batch.messages);
  batch.ackAll();
} catch (error) {
  batch.retryAll({ delaySeconds: 300 });
}

Exponential Backoff

async queue(batch: MessageBatch, env: Env): Promise<void> {
  for (const msg of batch.messages) {
    try {
      await processMessage(msg.body);
      msg.ack();
    } catch (error) {
      // 30s, 60s, 120s, 240s, 480s, ... up to 12h max
      const delay = Math.min(30 * (2 ** msg.attempts), 43200);
      msg.retry({ delaySeconds: delay });
    }
  }
}

Multiple Queues, Single Consumer

  async queue(batch: MessageBatch, env: Env): Promise<void> {
    switch (batch.queue) {
      case 'high-priority': await processUrgent(batch.messages); break;
      case 'low-priority': await processDeferred(batch.messages); break;
      case 'email': await sendEmails(batch.messages); break;
      default: batch.retryAll();
    }
  }
};

Consumer: Pull-based (HTTP)

// Pull messages
const response = await fetch(
  `https://api.cloudflare.com/client/v4/accounts/${ACCOUNT_ID}/queues/${QUEUE_ID}/messages/pull`,
  {
    method: 'POST',
    headers: { 'authorization': `Bearer ${API_TOKEN}`, 'content-type': 'application/json' },
    body: JSON.stringify({ visibility_timeout_ms: 6000, batch_size: 50 })
  }
);

const data = await response.json();

// Acknowledge
await fetch(
  `https://api.cloudflare.com/client/v4/accounts/${ACCOUNT_ID}/queues/${QUEUE_ID}/messages/ack`,
  {
    method: 'POST',
    headers: { 'authorization': `Bearer ${API_TOKEN}`, 'content-type': 'application/json' },
    body: JSON.stringify({
      acks: [{ lease_id: msg.lease_id }],
      retries: [{ lease_id: msg2.lease_id, delay_seconds: 600 }]
    })
  }
);

Interfaces

interface MessageBatch {
  readonly queue: string;
  readonly messages: Message[];
  ackAll(): void;
  retryAll(options?: QueueRetryOptions): void;
}

interface Message {
  readonly id: string;
  readonly timestamp: Date;
  readonly body: Body;
  readonly attempts: number;
  ack(): void;
  retry(options?: QueueRetryOptions): void;
}

interface QueueSendOptions {
  contentType?: 'text' | 'bytes' | 'json' | 'v8';
  delaySeconds?: number; // 0-43200
}