>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #3608903. --> Reported by: [rhiss](https://www.drupal.org/user/1638632) Related to !233 !209 >>> <h3 id="summary-problem-motivation">Problem/Motivation</h3> <p>The Charts module currently invokes chart-specific alter hooks whose hook names contain the chart ID.</p> <pre><div class="codeblock"><code class="language-php">$alter_hooks = ['chart'];<br><br>if ($chart_id) {<br>&nbsp; $alter_hooks[] = 'chart_' . $element['#chart_id'];<br>}<br><br>$this-&amp;gt;moduleHandler-&amp;gt;alter($alter_hooks, $element, $chart_id);<p>A similar pattern is used for chart definitions:</p> <pre><div class="codeblock"><code class="language-php">$alter_hooks = ['chart_definition'];<br><br>if ($element['#chart_id']) {<br>&nbsp; $alter_hooks[] = 'chart_definition_' . $chart_id;<br>}<br><br>$this-&amp;gt;moduleHandler-&amp;gt;alter(<br>&nbsp; $alter_hooks,<br>&nbsp; $chart_definition,<br>&nbsp; $element,<br>&nbsp; $chart_id,<br>);<p>When <code>#chart_id</code> contains a dynamically generated UUID, Drupal stores two new hook names in the <code>module_implements</code> cache for every distinct chart ID:</p> <pre><pre>chart_chart-&amp;lt;UUID&amp;gt;_alter<br>chart_definition_chart-&amp;lt;UUID&amp;gt;_alter</pre></pre><p>Drupal also caches empty hook lookup results, so this happens even when no module implements these generated UUID-specific hooks.</p> <p>On a production installation this resulted in an oversized <code>module_implements</code> cache entry:</p> <pre><pre>Cache entry: module_implements<br>Serialized size: approximately 86.4 MB<br>Total hook names: 1,234,496</pre></pre><p>The hook-name distribution showed that nearly all entries came from the two dynamic chart hook patterns:</p> <pre><pre>616,767 entries with a length of 54<br>616,764 entries with a length of 65</pre></pre><p>These correspond almost entirely to:</p> <pre><pre>chart_chart-&amp;lt;UUID&amp;gt;_alter<br>chart_definition_chart-&amp;lt;UUID&amp;gt;_alter</pre></pre><p>Only approximately 1,000 entries were regular Drupal hook names.</p> <p>This causes:</p> <ul> <li>Unbounded growth of the <code>module_implements</code> cache.</li> <li>A very large <code>cache_bootstrap</code> record.</li> <li>Increased database transfer and serialization overhead.</li> <li>Increased PHP memory usage during Drupal bootstrap.</li> <li>Increasing cache rebuild and request costs over time.</li> </ul> <h4 id="summary-steps-reproduce">Steps to reproduce</h4> <ol> <li>Install the Charts module using the <code>5.2.x-dev</code> branch.</li> <li>Render charts whose <code>#chart_id</code> values contain dynamically generated UUIDs.</li> <li>Render many charts with different chart IDs.</li> <li>Inspect the <code>module_implements</code> cache:</li> </ol> <pre><div class="codeblock"><code class="language-bash">drush php-eval '$c=\Drupal::cache("bootstrap")-&amp;gt;get("module_implements"); print "Hooks: ".count($c-&amp;gt;data).PHP_EOL."Size: ".round(strlen(serialize($c-&amp;gt;data))/1024/1024,2)." MB".PHP_EOL;'<p>Count the dynamically generated chart hook names:</p> <pre><div class="codeblock"><code class="language-bash">drush php-eval '$c=\Drupal::cache("bootstrap")-&amp;gt;get("module_implements"); $chart=0; $definition=0; foreach (array_keys($c-&amp;gt;data) as $hook) { if (str_starts_with((string) $hook, "chart_chart-")) { $chart++; } if (str_starts_with((string) $hook, "chart_definition_chart-")) { $definition++; } } print "chart_chart-*: ".$chart.PHP_EOL."chart_definition_chart-*: ".$definition.PHP_EOL;'<p><strong>Actual result:</strong></p> <p>A new cached hook name is created for every distinct chart ID:</p> <pre><pre>chart_chart-&amp;lt;UUID&amp;gt;_alter<br>chart_definition_chart-&amp;lt;UUID&amp;gt;_alter</pre></pre><p>The <code>module_implements</code> cache grows continuously.</p> <p><strong>Expected result:</strong></p> <p>Rendering charts with different runtime IDs must not create an unbounded number of hook names in Drupal's <code>module_implements</code> cache.</p> <h3 id="summary-proposed-resolution">Proposed resolution</h3> <p>Invoke only the stable generic alter hooks:</p> <pre><div class="codeblock"><code class="language-php">$this-&amp;gt;moduleHandler-&amp;gt;alter(<br>&nbsp; 'chart',<br>&nbsp; $element,<br>&nbsp; $chart_id,<br>);<p>And:</p> <pre><div class="codeblock"><code class="language-php">$this-&amp;gt;moduleHandler-&amp;gt;alter(<br>&nbsp; 'chart_definition',<br>&nbsp; $chart_definition,<br>&nbsp; $element,<br>&nbsp; $chart_id,<br>);<p>The chart ID remains available to hook implementations as an argument. Implementations that need chart-specific behavior can inspect <code>$chart_id</code> inside the generic hook:</p> <pre><div class="codeblock"><code class="language-php">/**<br> * Implements hook_chart_alter().<br> */<br>function mymodule_chart_alter(array &amp;amp;$element, $chart_id): void {<br>&nbsp; if ($chart_id !== 'chart-example') {<br>&nbsp;&nbsp;&nbsp; return;<br>&nbsp; }<br><br>&nbsp; // Apply chart-specific changes.<br>}<p>The same approach applies to chart definitions:</p> <pre><div class="codeblock"><code class="language-php">/**<br> * Implements hook_chart_definition_alter().<br> */<br>function mymodule_chart_definition_alter(<br>&nbsp; array &amp;amp;$definition,<br>&nbsp; array $element,<br>&nbsp; $chart_id,<br>): void {<br>&nbsp; if ($chart_id !== 'chart-example') {<br>&nbsp;&nbsp;&nbsp; return;<br>&nbsp; }<br><br>&nbsp; // Apply chart-definition-specific changes.<br>}<p>The proposed patch also removes the dynamic hook documentation for:</p> <pre><pre>hook_chart_CHART_ID_alter()<br>hook_chart_definition_CHART_ID_alter()</pre></pre><p>These dynamic hooks are the source of the unbounded cache-key cardinality.</p> <h3 id="summary-remaining-tasks">Remaining tasks</h3> <ol> <li>Review the proposed approach.</li> <li>Decide how the backward compatibility impact should be handled.</li> <li>Add automated coverage proving that different chart IDs do not create chart-ID-specific hook cache entries.</li> <li>Add automated coverage confirming that <code>$chart_id</code> remains available to the generic alter hooks.</li> <li>Update API documentation and change records if required.</li> <li>Test against the latest <code>5.2.x-dev</code> branch.</li> <li>Confirm compatibility with supported Drupal core versions.</li> <li>Review and merge the attached patch or corresponding merge request.</li> </ol> <h3 id="summary-ui-changes">User interface changes</h3> <p>None.</p> <h3 id="summary-api-changes">API changes</h3> <p>The following dynamically named hooks are removed:</p> <pre><pre>hook_chart_CHART_ID_alter()<br>hook_chart_definition_CHART_ID_alter()</pre></pre><p>Use the generic hooks instead:</p> <pre><div class="codeblock"><code class="language-php">hook_chart_alter(array &amp;amp;$element, $chart_id)<pre><div class="codeblock"><code class="language-php">hook_chart_definition_alter(<br>&nbsp; array &amp;amp;$definition,<br>&nbsp; array $element,<br>&nbsp; $chart_id,<br>)<p>Chart-specific behavior should be selected by inspecting <code>$chart_id</code> inside the generic hook implementation.</p> <p>This is a backward compatibility change for code that currently implements chart-ID-specific hooks such as:</p> <pre><div class="codeblock"><code class="language-php">function mymodule_chart_chart_example_alter(array &amp;amp;$element): void {<br>}<p>Equivalent logic can be moved to the generic hook:</p> <pre><div class="codeblock"><code class="language-php">function mymodule_chart_alter(array &amp;amp;$element, $chart_id): void {<br>&nbsp; if ($chart_id === 'chart-example') {<br>&nbsp;&nbsp;&nbsp; // Apply chart-specific changes.<br>&nbsp; }<br>}<p>The maintainers should decide whether this can be accepted as a bug fix in <code>5.2.x</code>, whether a deprecation path is required, or whether the change needs to target a later minor or major release.</p> <h3 id="summary-data-model-changes">Data model changes</h3> <p>None.</p> <p>No database schema or configuration schema changes are required.</p> <p>After deploying the fix, existing oversized cache entries can be removed using a normal cache rebuild:</p> <pre><div class="codeblock"><code class="language-bash">drush cr<p><strong>Release notes snippet:</strong></p> <p>Fixed an issue where chart IDs were used as part of dynamically generated alter-hook names. Sites rendering charts with unique runtime IDs could accumulate a very large <code>module_implements</code> cache entry, increasing database storage, bootstrap overhead, and PHP memory usage.</p> <p>The chart ID remains available as an argument to the generic <code>hook_chart_alter()</code> and <code>hook_chart_definition_alter()</code> hooks.</p> <p><strong>AI disclosure:</strong> AI was used to help structure and edit this issue report. The technical findings, production measurements, patch, and proposed resolution were reviewed and verified by the issue author.</p> </code></div></pre></code></div></pre></code></div></pre></code></div></pre></code></div></pre></code></div></pre></code></div></pre></code></div></pre></code></div></pre></code></div></pre></code></div></pre></code></div></pre></code></div></pre> >>> [!note] Pre-migration files - [charts-dynamic-hooks-cache.patch](https://www.drupal.org/files/issues/2026-07-07/charts-dynamic-hooks-cache.patch) >>>