Merge pull request #3142 from kevinzakka:simulate-fix

PiperOrigin-RevId: 878575288
Change-Id: Ib3f820d84b0b9bfa25141e4360ddc339abbf0d50

python/mujoco/mjpython/mjpython.mm

@@ -36,6 +36,13 @@ extern char **environ;  // for execve
 // so that we can dlsym and call them from Python via ctypes.
 __attribute__((used)) void mjpython_hide_dock_icon() {
   [NSApp setActivationPolicy:NSApplicationActivationPolicyAccessory];
+
+  // Drain pending Cocoa events on the main thread. The activation policy
+  // change triggers an asynchronous dock/screen reconfiguration via
+  // SkyLight. If we return before it's processed, the notification lands
+  // on a GCD worker thread and hits NSScreen's main-thread assertion.
+  NSDate* soon = [NSDate dateWithTimeIntervalSinceNow:0.01];
+  [[NSRunLoop mainRunLoop] runUntilDate:soon];
 }
 __attribute__((used)) void mjpython_show_dock_icon() {
   [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular];

python/mujoco/simulate.cc

@@ -247,6 +247,11 @@ class SimulateWrapper {
     if (simulate_) {
       py::gil_scoped_release no_gil;
       while (atomic.load() != expected) {
+        // If the viewer is exiting, stop waiting. The render loop will
+        // never consume the pending request once it has set exitrequest.
+        if (simulate_->exitrequest.load()) {
+          return true;
+        }
         // TODO(robotics-simulation): replace with `atomic.wait(expected)` when
         // we migrate python bindings to C++20 (we may need to drop GCC 10).
         std::this_thread::yield();