Add some workariunds for crashes on exit without closing all clients.

GitOrigin-RevId: 5c74e9fe6951b6a8eb65d6c1e5ddf7bf8e0c8163

td/telegram/Client.cpp

@@ -176,9 +176,11 @@ class ClientManager::Impl final {
       }
     }
     while (!tds_.empty() && !ExitGuard::is_exited()) {
-      receive(10);
+      receive(0.1);
+    }
+    if (!ExitGuard::is_exited()) {  // prevent closing of schedulers from already killed by OS threads
+      concurrent_scheduler_->finish();
     }
-    concurrent_scheduler_->finish();
   }
 
  private:
@@ -380,7 +382,9 @@ class MultiImpl {
       Scheduler::instance()->finish();
     }
     scheduler_thread_.join();
-    concurrent_scheduler_->finish();
+    if (!ExitGuard::is_exited()) {  // prevent closing of schedulers from already killed by OS threads
+      concurrent_scheduler_->finish();
+    }
   }
 
  private:
@@ -519,11 +523,14 @@ class ClientManager::Impl final {
   Impl(Impl &&) = delete;
   Impl &operator=(Impl &&) = delete;
   ~Impl() {
+    if (ExitGuard::is_exited()) {
+      return;
+    }
     for (auto &it : impls_) {
       close_impl(it.first);
     }
     while (!impls_.empty() && !ExitGuard::is_exited()) {
-      receive(10);
+      receive(0.1);
     }
   }
 
@@ -571,7 +578,7 @@ class Client::Impl final {
   ~Impl() {
     multi_impl_->close(td_id_);
     while (!ExitGuard::is_exited()) {
-      auto response = receiver_.receive(10.0);
+      auto response = receiver_.receive(0.1);
       if (response.object == nullptr && response.client_id != 0 && response.request_id == 0) {
         break;
       }

tdactor/td/actor/impl/Scheduler.cpp

@@ -111,6 +111,7 @@ void Scheduler::ServiceActor::tear_down() {
 /*** SchedlerGuard ***/
 SchedulerGuard::SchedulerGuard(Scheduler *scheduler, bool lock) : scheduler_(scheduler) {
   if (lock) {
+    // the next check can fail if OS killed the scheduler's thread without releasing the guard
     CHECK(!scheduler_->has_guard_);
     scheduler_->has_guard_ = true;
   }