Main thread vs Worker vs SharedArrayBuffer — who owns which buffer.

Concurrency & Streams

Shared memory models

<h2>Summary</h2>
<p>Conflict-free replicated data types merge concurrent edits without central lock — eventual consistency. Used in Figma-like editors, Yjs, Automerge. Trade memory/size for merge correctness. UI shows merged state; not same as operational transform server authority.</p>
<h2>Code example</h2>
<pre><code class="language-javascript">// G-Counter merge: take max per node
function mergeGCounter(a, b) {
  const keys = new Set([...Object.keys(a), ...Object.keys(b)]);
  const result = {};
  for (const k of keys) {
    result[k] = Math.max(a[k] ?? 0, b[k] ?? 0);
  }
  return result;
}
</code></pre>
<h2>Key points</h2>
<ul>
<li>Conflict-free replicated data types merge concurrent edits without central lock — eventual consistency.</li>
<li>Used in Figma-like editors, Yjs, Automerge.</li>
<li>Trade memory/size for merge correctness.</li>
<li>UI shows merged state; not same as operational transform server authority.</li>
</ul>
<h2>Further reading</h2>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/API/IndexedDB_API">CRDT overview</a></li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm">Structured cloning</a></li>
</ul>
<h2>Related concepts</h2>
<ul>
<li><a href="/blogs/level-8-webrtc-basics">WebRTC basics</a></li>
<li><a href="/blogs/level-8-shared-memory-models">Shared memory models</a></li>
</ul>


Conflict-free replicated data types merge concurrent edits without central lock — eventual consistency.

CRDT basics for collaboration

P2P media/data via ICE/STUN/TURN for NAT traversal — signaling server sets up connection.