Fix websocket CPU usage issue

packages/bun-usockets/src/crypto/openssl.c

@@ -703,7 +703,7 @@ int ssl_is_low_prio(struct us_internal_ssl_socket_t *s) {
    * step is CPU intensive, and we want to speed up the rest of connection
    * establishing if the CPU intensive work is already done, so fully
    * established connections increase lineary over time under high load */
-  return SSL_in_init(s->ssl);
+  return SSL_get_state(s->ssl) & SSL_ST_BEFORE;
 }
 
 /* Per-context functions */

test/js/bun/http/bun-websocket-cpu-fixture.js

@@ -0,0 +1,65 @@
+import path from "path";
+
+const server = Bun.serve({
+  port: 0,
+  idleTimeout: 100,
+  tls: {
+    cert: Bun.file(path.join(import.meta.dir, "fixtures", "cert.pem")),
+    key: Bun.file(path.join(import.meta.dir, "fixtures", "cert.key")),
+  },
+  fetch(req, server) {
+    if (server.upgrade(req)) {
+      return;
+    }
+    return new Response("Upgrade failed", { status: 500 });
+  },
+  websocket: {
+    idleTimeout: 120,
+    open(ws) {},
+    message(ws, message) {
+      ws.send(message);
+    },
+  },
+});
+
+const ws = new WebSocket(`wss://${server.hostname}:${server.port}`, { tls: { rejectUnauthorized: false } });
+await Bun.sleep(1000);
+for (let i = 0; i < 1000; i++) {
+  ws.send("hello");
+}
+let bytesReceived = 0;
+ws.onmessage = event => {
+  bytesReceived += event.data.length;
+};
+
+let previousUsage = process.cpuUsage();
+let previousTime = Date.now();
+
+let count = 0;
+setInterval(() => {
+  count++;
+
+  const currentUsage = process.cpuUsage(previousUsage);
+  const currentTime = Date.now();
+
+  const userCpuTime = currentUsage.user; // microseconds
+  const systemCpuTime = currentUsage.system; // microseconds
+  const totalCpuTime = userCpuTime + systemCpuTime;
+
+  const timeDeltaMs = currentTime - previousTime; // milliseconds
+  const timeDeltaMicroseconds = timeDeltaMs * 1000; // convert to microseconds
+
+  // Calculate percentage for the current process
+  const cpuUsagePercentage = (totalCpuTime / timeDeltaMicroseconds) * 100;
+
+  console.log(`CPU Usage: ${cpuUsagePercentage.toFixed(2)}%`);
+
+  previousUsage = process.cpuUsage(); // Update for the next interval
+  previousTime = currentTime;
+
+  if (count == 2) {
+    server.stop(true);
+    // The expected value is around 0.XX%, but we allow a 10% margin of error to account for potential flakiness.
+    process.exit(cpuUsagePercentage < 10 ? 0 : 1);
+  }
+}, 1000);

test/js/bun/http/serve.test.ts

@@ -2189,3 +2189,15 @@ it.concurrent("#20283", async () => {
   // there should be no cookies and the clone should have succeeded
   expect(json).toEqual({ cookies: {}, clonedCookies: {} });
 });
+
+it.concurrent("should not use 100% CPU when idle", async () => {
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), join(import.meta.dir, "bun-websocket-cpu-fixture.js")],
+    env: bunEnv,
+    stdout: "inherit",
+    stderr: "inherit",
+    stdin: "inherit",
+  });
+  const code = await proc.exited;
+  expect(code).toBe(0);
+});