Keep one long-lived yt-dlp worker process instead of spawning per call

server/server.js

@@ -50,6 +50,7 @@ import { createPartyHub } from './party.js';
 import { registerUploadRoutes } from './uploads.js';
 import * as innertube from './innertube.js';
 import QRCode from 'qrcode';
+import { createYtdlpPool } from './ytdlp-pool.js';
 import { dirname, join as pathJoin } from 'node:path';
 
 // A media proxy must not die because one client's stream hit an edge case
@@ -142,7 +143,7 @@ const CHANNEL_LIMIT = 60;
 // concurrent request — including in-flight /api/download proxy streams, which
 // Bun then kills at its idle timeout ("fetch failed" mid-download on clients).
 // Rejects on non-zero exit.
-function runYtdlp(args, { signal } = {}) {
+function runYtdlpSpawn(args, { signal } = {}) {
   return new Promise((resolve, reject) => {
     const child = spawn(YTDLP, args, { stdio: ['ignore', 'pipe', 'pipe'] });
     const t0 = Date.now();
@@ -170,6 +171,29 @@ function runYtdlp(args, { signal } = {}) {
   });
 }
 
+// Read-only calls (-J, --dump-json) go to long-lived workers that import
+// yt_dlp once (~1 s saved per call). Downloads keep spawning. Pool trouble
+// (not a yt-dlp error) falls back to a spawn. YTDLP_WORKER=0 disables it.
+const ytdlpPool = process.env.YTDLP_WORKER === '0' ? null : createYtdlpPool({
+  ytdlpPath: Bun.which(YTDLP) || YTDLP,
+  size: Math.max(1, Number(process.env.YTDLP_WORKERS) || 2),
+});
+function runYtdlp(args, opts = {}) {
+  if (!opts.pooled || !ytdlpPool || opts.signal) return runYtdlpSpawn(args, opts);
+  const t0 = Date.now();
+  return ytdlpPool.run(args).then(
+    (out) => { console.log(`[ytdlp] pooled ${Date.now() - t0}ms ok`); return out; },
+    (err) => {
+      if (err.poolInfra) return runYtdlpSpawn(args, opts);
+      // A bot check can stick to a long-lived process: replace the workers and
+      // answer this call the old way, from a fresh process.
+      if (BOT_CHECK_RE.test(err.message)) { ytdlpPool.recycle(); return runYtdlpSpawn(args, opts); }
+      console.log(`[ytdlp] pooled ${Date.now() - t0}ms fail`);
+      throw err;
+    },
+  );
+}
+
 // YouTube intermittently answers the default (web) innertube client with
 // "Sign in to confirm you're not a bot" — a per-IP rate signal, not a
 // per-video one, so the SAME video that just saved fine fails minutes later
@@ -396,7 +420,7 @@ app.get('/api/search', async (c) => {
         `ytsearch${SEARCH_LIMIT}:${q}`,
         '--dump-json', '--flat-playlist',
         '--no-warnings', '--ignore-errors',
-      ]);
+      ], { pooled: true });
       yt = parseCards(out);
     }
     const results = [...mine, ...yt];
@@ -421,7 +445,7 @@ app.get('/api/channel', async (c) => {
       '--dump-json', '--flat-playlist',
       '--no-warnings', '--ignore-errors',
       '--playlist-end', String(CHANNEL_LIMIT),
-    ]);
+    ], { pooled: true });
     const results = parseCards(out);
     // Extract channel name + URL from the first record
     const first = results[0];
@@ -476,7 +500,7 @@ async function resolveStreamsUncached(videoId) {
   const cached = streamCache.get(videoId);
   if (cached && now < cached.expiresAt) return cached;
 
-  const out = await runYtdlpResilient(['-J', '--no-warnings', `https://www.youtube.com/watch?v=${videoId}`]);
+  const out = await runYtdlpResilient(['-J', '--no-warnings', `https://www.youtube.com/watch?v=${videoId}`], { pooled: true });
   const info = JSON.parse(out);
   const raw = Array.isArray(info.formats) ? info.formats : [];
   const formats = [];
@@ -1760,7 +1784,7 @@ app.get('/api/playlist/expand', async (c) => {
       '--dump-json', '--flat-playlist',
       '--no-warnings', '--ignore-errors',
       '--playlist-end', '201',
-    ]);
+    ], { pooled: true });
     const parsed = parseCards(out);
     let title = '';
     for (const line of out.split('\n')) {