Merge pull request #7607 from QwikDev/tweak-preloader

- don't decrease the probability of array preloads
- limit ssr preloads to the first 15 qrls on the page
- allow somewhat more ssr preloads
- when preloading at 100%, also preload the entire dynamic graph at 95%

Author: wmertens

packages/qwik/src/core/preloader/preloader.unit.ts

@@ -21,6 +21,6 @@ test('preloader script', () => {
    * dereference objects etc, but that actually results in worse compression
    */
   const compressed = compress(Buffer.from(preLoader), { mode: 1, quality: 11 });
-  expect(compressed.length).toBe(1716);
-  expect(preLoader.length).toBe(5114);
+  expect(compressed.length).toBe(1722);
+  expect(preLoader.length).toBe(5107);
 });

packages/qwik/src/core/preloader/queue.ts

@@ -179,12 +179,16 @@ export const adjustProbabilities = (
       const prevAdjust = dep.$factor$;
       /**
        * The chance that a dep won't be loaded is 1-(the chance that the dep will be loaded)*(the
-       * chance that the current bundle will be loaded)
+       * chance that the current bundle will be loaded).
        *
        * We can multiply this chance together with all other bundle adjustments to get the chance
-       * that a dep will be loaded given all the chances of the other bundles
+       * that a dep will be loaded given all the chances of the other bundles.
+       *
+       * But when we're very likely to load the current bundle, make the dynamic imports more likely
+       * too.
        */
-      const newInverseProbability = 1 - dep.$probability$ * probability;
+      const newInverseProbability =
+        dep.$probability$ !== 1 && adjustFactor < 0.1 ? 0.05 : 1 - dep.$probability$ * probability;
 
       /** We need to undo the previous adjustment */
       const factor = newInverseProbability / prevAdjust;
@@ -216,7 +220,6 @@ export const preload = (name: string | (number | string)[], probability?: number
         inverseProbability = 1 - item / 10;
       } else {
         handleBundle(item, inverseProbability);
-        inverseProbability *= 1.005;
       }
     }
   } else {

packages/qwik/src/server/preload-impl.ts

@@ -1,6 +1,6 @@
 import { Fragment, jsx, type JSXNode } from '@builder.io/qwik';
 import type { ResolvedManifest } from '../optimizer/src/types';
-import { expandBundles } from './prefetch-strategy';
+import { expandBundles } from './preload-strategy';
 import type { PreloaderOptions } from './types';
 
 export function includePreloader(
@@ -126,8 +126,8 @@ function normalizePreLoaderOptions(
 }
 
 const PreLoaderOptionsDefault: Required<PreloaderOptions> = {
-  ssrPreloads: 5,
-  ssrPreloadProbability: 0.7,
+  ssrPreloads: 7,
+  ssrPreloadProbability: 0.5,
   debug: false,
   maxIdlePreloads: 25,
   preloadProbability: 0.35,

packages/qwik/src/server/prefetch-strategy.ts renamed to packages/qwik/src/server/preload-strategy.ts

@@ -1,7 +1,7 @@
 import type { ResolvedManifest } from '@builder.io/qwik/optimizer';
 import { getQueue, preload, resetQueue } from '../core/preloader/queue';
 import type { QRLInternal } from '../core/qrl/qrl-class';
-import { flattenPrefetchResources } from './prefetch-utils';
+import { flattenPrefetchResources } from './preload-utils';
 import type { RenderToStringOptions, SnapshotResult } from './types';
 import { getPlatform } from '@builder.io/qwik';
 import { getSymbolHash } from './platform';
@@ -66,10 +66,12 @@ export const expandBundles = (names: string[], resolvedManifest?: ResolvedManife
   resetQueue();
 
   let probability = 0.99;
-  for (const name of names) {
+  // we assume that after 15 symbols, we're beyond the first screenful of content
+  // the preloader will load the rest
+  for (const name of names.slice(0, 15)) {
     preload(name, probability);
     // later symbols have less probability
-    probability *= 0.95;
+    probability *= 0.85;
   }
 
   return getQueue().filter(

packages/qwik/src/server/prefetch-utils.ts renamed to packages/qwik/src/server/preload-utils.ts

@@ -1,5 +1,5 @@
 import { assert, test } from 'vitest';
-import { flattenPrefetchResources } from './prefetch-utils';
+import { flattenPrefetchResources } from './preload-utils';
 
 test('flattenPrefetchResources, no imports', () => {
   const p = [

packages/qwik/src/server/prefetch-utils.unit.ts renamed to packages/qwik/src/server/preload-utils.unit.ts

@@ -6,7 +6,7 @@ import { QInstance } from '../core/util/markers';
 import type { ResolvedManifest, SymbolMapper } from '../optimizer/src/types';
 import { getSymbolHash, setServerPlatform } from './platform';
 import { includePreloader } from './preload-impl';
-import { getPreloadPaths } from './prefetch-strategy';
+import { getPreloadPaths } from './preload-strategy';
 import { getQwikLoaderScript } from './scripts';
 import type {
   QwikManifest,