https://4f0a9a3b.wangpeng.pages.dev/en/tags/distributed-lock/Recent content in Distributed Lock on Zhuifeng NotesHugoenTue, 25 Aug 2026 00:00:00 +0000https://4f0a9a3b.wangpeng.pages.dev/en/tech/zookeeper/coordination/Tue, 25 Aug 2026 00:00:00 +0000https://4f0a9a3b.wangpeng.pages.dev/en/tech/zookeeper/coordination/<p>ZooKeeper offers primitive-level coordination; almost every distributed coordination need can be built from the combination of &ldquo;ephemeral node + sequential node + Watcher&rdquo;.</p> <h2 id="leader-election">Leader Election </h2> <p>Each candidate creates an ephemeral sequential node under <code>/election</code>; the one with the smallest sequence becomes Master. Non-smallest nodes watch their predecessor; when the predecessor disappears they re-evaluate whether they are now smallest, achieving automatic failover:</p> <div class="td-code td-code--untitled" id="td-code-889a3404-fence-0" data-td-code data-td-code-auto-id data-td-language="text" data-td-line-count="4"> <div class="td-code__viewport" id="td-code-889a3404-fence-0-viewport" data-td-code-viewport><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-text" data-lang="text"><span class="line"><span class="cl">/election </span></span><span class="line"><span class="cl"> ├── /n_0000000001 (master) </span></span><span class="line"><span class="cl"> ├── /n_0000000002 (watches 001) </span></span><span class="line"><span class="cl"> └── /n_0000000003 (watches 002)</span></span></code></pre></div></div> </div> <h2 id="configuration-center">Configuration Center </h2> <p>Write configuration into a persistent node; clients read it and register a Watcher. On configuration change the client receives a notification and hot-reloads without restarting the app. Keep config nodes small to avoid oversized single pushes.</p>