https://vacua.dev/tags/concurrency/Recent content in Concurrency on Brian FaustHugoen-USMon, 01 Jan 0001 00:00:00 +0000https://vacua.dev/a-version-column-is-not-concurrency-control/Sun, 01 Jan 2023 00:00:00 +0000https://vacua.dev/a-version-column-is-not-concurrency-control/<p>A capacity pool has ten units available. Two workers load it before either one writes:</p> <figure class="code-figure"> <div class="code-block" data-copy-code> <button class="copy-code" type="button" aria-label="Copy code">copy</button><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-text" data-lang="text"><span class="line"><span class="cl">worker A loads: version 0, reserved 0 </span></span><span class="line"><span class="cl">worker B loads: version 0, reserved 0 </span></span><span class="line"><span class="cl"> </span></span><span class="line"><span class="cl">worker A allocates 6 to allocation-a </span></span><span class="line"><span class="cl">worker B allocates 6 to allocation-b</span></span></code></pre></div> </div> </figure> <p>Both decisions pass the aggregate&rsquo;s rule. Each worker sees ten remaining units. They cannot both belong to one ordered history: after either allocation, only four remain.</p>