Overview
I started doing some profiling of XB for performance. Viewing an XB page took 228ms roughly. However I noticed 51x queries to key_value_expire. Which is where auto-saves live.
select ... from key_value_expire where ? > :now and ? in (:keys__0) and ? = :collection
Which I thought was weird: I was viewing the page as an anonymous user. JsComponent::getScopedDependencies is loading autosaves. It's pretty cheap but has a scaling problem. 17 calls was only 13ms, but someone could have 50 components. AutoSaveManager has a cache and on cache miss it hits the DB for the auto-save. If we're not editing the entity, there is no auto-save. Which means we always cache miss and hit the DB for no reason.
I had 198 calls to Memcached::getMulti as well.
The problem is that $dependencyAutoSave = $this->autoSaveManager->getAutoSaveEntity($js_component_dependency); is always called even if we're not in a preview. Later on in shouldLoadAssetFromAutoSave there is a preview check.
We should avoid loading auto-saves unless in preview when rendering components.
Proposed resolution
In renderComponent we should use an empty auto-save if not in preview:
public function renderComponent(array $inputs, string $componentUuid, bool $isPreview = FALSE): array {
$component = $this->getJavaScriptComponent();
if ($isPreview) {
$autoSave = $this->autoSaveManager->getAutoSaveEntity($component);
} else {
$autoSave = AutoSaveEntity::empty();
}
This change brought my response time from 228ms to 106ms! My memcache calls went from 198 calls to 63 and call DB queries to key_value_expire were removed.
User interface changes
