How Zookeeper Powers Synchronous and FIFO Distributed Queues

Distributed queue is a simple concept that helps achieve cross‑process, cross‑host, and cross‑network data sharing and transmission.

Zookeeper provides a reliable way to implement distributed queues and supports two types: synchronous queues and FIFO queues.

Implementation Idea

01 Synchronous Queue

In Zookeeper, create a root node queue_sync as the queue. Consumers watch the node /queue_sync/start , which initially does not exist, so nothing happens at first. The enqueue operation creates a child node under queue_sync and counts the total number of children. When the count matches the target queue size, the node /queue_sync/start is created; this state change notifies the watchers that all members have arrived, allowing them to proceed with their subsequent processes.

02 FIFO Queue

In Zookeeper, create a root node queue_fifo as the queue. The enqueue operation creates sequential child nodes under queue_fifo and stores the data inside each node. The dequeue operation finds the child node with the smallest sequence number, retrieves its data, and then deletes that node, thus following the first‑in‑first‑out principle.