Avoid busy-spin waits in zombie cleanup lock

src/reliability/zombie-cleanup.ts

@@ -12,6 +12,14 @@
 const LOCK_RETRY_MS = 50;
 const LOCK_TIMEOUT_MS = 5000;
 
+export function sleepWithoutBusySpin(ms: number): void {
+  const duration = Math.max(0, Math.floor(ms));
+  if (duration === 0) return;
+  const buffer = new SharedArrayBuffer(4);
+  const view = new Int32Array(buffer);
+  Atomics.wait(view, 0, 0, duration);
+}
+
 function acquireLock(): boolean {
   const deadline = Date.now() + LOCK_TIMEOUT_MS;
   while (Date.now() < deadline) {
@@ -34,8 +42,7 @@
           releaseLock();
           continue;
         }
-        const waitUntil = Date.now() + LOCK_RETRY_MS;
-        while (Date.now() < waitUntil) { /* spin */ }
+        sleepWithoutBusySpin(LOCK_RETRY_MS);
         continue;
       }
       return false;
@@ -331,7 +338,7 @@
     const { orphanedIds, liveIds } = getOrphanedAndLiveDeviceIds();
     const protectedIds = new Set([...knownDeviceIds, ...liveIds]);
 
     for (const runtime of Object.values(data.devices) as any[]) {
       for (const device of runtime) {
         if (device.state === 'Booted'
             && orphanedIds.has(device.udid)
@@ -399,7 +406,7 @@
     }, resolvedInterval);
     cleanupInterval.unref();
   }, resolvedGrace);
   (cleanupGraceTimeout as any).unref?.();
 }
 
 /**

tests/unit/zombie-cleanup-lock.test.ts

@@ -0,0 +1,16 @@
+import { sleepWithoutBusySpin } from '../../src/reliability/zombie-cleanup';
+
+describe('zombie cleanup registry lock wait helper', () => {
+  it('returns immediately for non-positive durations', () => {
+    const start = Date.now();
+    sleepWithoutBusySpin(0);
+    sleepWithoutBusySpin(-10);
+    expect(Date.now() - start).toBeLessThan(25);
+  });
+
+  it('waits for approximately the requested duration without a JavaScript spin loop', () => {
+    const start = Date.now();
+    sleepWithoutBusySpin(15);
+    expect(Date.now() - start).toBeGreaterThanOrEqual(10);
+  });
+});