diff --git a/async_simple/Signal.h b/async_simple/Signal.h
index 8f5dfd30..bb74b9bc 100644
--- a/async_simple/Signal.h
+++ b/async_simple/Signal.h
@@ -205,14 +205,17 @@ class Slot {
                       "we dont allow emplace an empty signal handler");
         logicAssert(std::popcount(static_cast<uint64_t>(type)) == 1,
                     "It's not allow to emplace for multiple signals");
-        // trigger-once signal has already been triggered
+        auto handler = std::make_unique<detail::SignalSlotSharedState::Handler>(
+            std::forward<Args>(args)...);
+        auto oldHandlerPtr = loadHandler<true>(type);
+        // check trigger-once signal has already been triggered
+        // if signal has already been triggered, return false
         if (!detail::SignalSlotSharedState::isMultiTriggerSignal(type) &&
             (signal()->state() & type)) {
             return false;
         }
-        auto handler = std::make_unique<detail::SignalSlotSharedState::Handler>(
-            std::forward<Args>(args)...);
-        auto oldHandlerPtr = loadHandler<true>(type);
+        // if signal triggered later, we will found it by atomic handler CAS
+        // failed.
         auto oldHandler = oldHandlerPtr->load(std::memory_order_acquire);
         if (oldHandler ==
             &detail::SignalSlotSharedState::HandlerManager::emittedTag) {
diff --git a/async_simple/coro/Collect.h b/async_simple/coro/Collect.h
index cb224556..41f5487e 100644
--- a/async_simple/coro/Collect.h
+++ b/async_simple/coro/Collect.h
@@ -166,7 +166,7 @@ struct CollectAnyAwaiter {
                 _slot, [c = continuation, e = event, size = input.size()](
                            SignalType type, Signal*) mutable {
                     auto count = e->downCount();
-                    if (count > size + 1) {
+                    if (count == size + 1) {
                         c.resume();
                     }
                 })) {  // has canceled
@@ -186,7 +186,7 @@ struct CollectAnyAwaiter {
                     assert(e != nullptr);
                     auto count = e->downCount();
                     // n+1: n coro + 1 cancel handler
-                    if (count > size + 1) {
+                    if (count == size + 1) {
                         _result = std::make_unique<ResultType>();
                         _result->_idx = i;
                         _result->_value = std::move(result);
@@ -268,7 +268,7 @@ struct CollectAnyVariadicAwaiter {
                 _slot, [c = continuation, e = event](SignalType type,
                                                      Signal*) mutable {
                     auto count = e->downCount();
-                    if (count > std::tuple_size<InputType>() + 1) {
+                    if (count == std::tuple_size<InputType>() + 1) {
                         c.resume();
                     }
                 })) {  // has canceled
@@ -290,7 +290,7 @@ struct CollectAnyVariadicAwaiter {
                             res) mutable {
                         auto count = e->downCount();
                         // n+1: n coro + 1 cancel handler
-                        if (count > std::tuple_size<InputType>() + 1) {
+                        if (count == std::tuple_size<InputType>() + 1) {
                             _result = std::make_unique<ResultType>(
                                 std::in_place_index_t<index>(), std::move(res));
                             if (auto ptr = local->getSlot(); ptr) {
@@ -388,7 +388,10 @@ struct CollectAllAwaiter {
             _slot->chainedSignal(_signal.get());
 
         auto executor = promise_type._executor;
-        for (size_t i = 0; i < _input.size(); ++i) {
+
+        _event.setAwaitingCoro(continuation);
+        auto size = _input.size();
+        for (size_t i = 0; i < size; ++i) {
             auto& exec = _input[i]._coro.promise()._executor;
             if (exec == nullptr) {
                 exec = executor;
@@ -422,11 +425,6 @@ struct CollectAllAwaiter {
             }
             func();
         }
-        _event.setAwaitingCoro(continuation);
-        auto awaitingCoro = _event.down();
-        if (awaitingCoro) {
-            awaitingCoro.resume();
-        }
     }
     inline auto await_resume() { return std::move(_output); }
 
@@ -602,10 +600,6 @@ struct CollectAllVariadicAwaiter {
                 }
             }(std::get<index>(_inputs), std::get<index>(_results)),
             ...);
-
-        if (auto awaitingCoro = _event.down(); awaitingCoro) {
-            awaitingCoro.resume();
-        }
     }
 
     void await_suspend(std::coroutine_handle<> continuation) {
diff --git a/async_simple/coro/CountEvent.h b/async_simple/coro/CountEvent.h
index ad33b378..2dae20da 100644
--- a/async_simple/coro/CountEvent.h
+++ b/async_simple/coro/CountEvent.h
@@ -34,7 +34,7 @@ namespace detail {
 // The last 'down' will resume the awaiting coroutine on this event.
 class CountEvent {
 public:
-    CountEvent(size_t count) : _count(count + 1) {}
+    CountEvent(size_t count) : _count(count) {}
     CountEvent(const CountEvent&) = delete;
     CountEvent(CountEvent&& other)
         : _count(other._count.exchange(0, std::memory_order_relaxed)),