diff --git a/src/platform/waiter_linux.h b/src/platform/waiter_linux.h
index 7140006..b97b73a 100644
--- a/src/platform/waiter_linux.h
+++ b/src/platform/waiter_linux.h
@@ -2,18 +2,8 @@
 
 #include <pthread.h>
 
-#include <cstring>
-#include <atomic>
-#include <string>
-#include <utility>
-#include <tuple>
-
 #include "def.h"
 #include "log.h"
-#include "shm.h"
-#include "rw_lock.h"
-#include "id_pool.h"
-#include "pool_alloc.h"
 
 #include "platform/detail.h"
 
@@ -115,9 +105,9 @@ public:
 #pragma pop_macro("IPC_PTHREAD_FUNC_")
 
 class semaphore {
-    mutex     lock_;
-    condition cond_;
-    long      counter_ = 0;
+    mutex         lock_;
+    condition     cond_;
+    long volatile counter_ = 0;
 
 public:
     bool open() {
diff --git a/src/platform/waiter_win.h b/src/platform/waiter_win.h
index 469631a..1e9ed57 100644
--- a/src/platform/waiter_win.h
+++ b/src/platform/waiter_win.h
@@ -18,7 +18,8 @@ namespace ipc {
 namespace detail {
 
 class waiter {
-    std::atomic<long> counter_ { 0 };
+    long volatile counter_ = 0;
+    spin_lock     lock_;
 
 public:
     using handle_t = HANDLE;
@@ -37,51 +38,32 @@ public:
         ::CloseHandle(h);
     }
 
-    template <typename F>
-    static bool multi_wait_if(std::tuple<waiter*, handle_t> const * all, std::size_t size, F&& pred) {
-        if (all == nullptr || size == 0) {
-            return false;
-        }
-        if (!std::forward<F>(pred)()) return true;
-        auto hs = static_cast<handle_t*>(mem::alloc(sizeof(handle_t) * size));
-        IPC_UNUSED_ auto guard = unique_ptr(hs, [size](void* p) { mem::free(p, sizeof(handle_t) * size); });
-        std::size_t i = 0;
-        for (; i < size; ++i) {
-            auto& info = all[i];
-            if ((std::get<0>(all[i]) == nullptr) ||
-                (std::get<1>(all[i]) == invalid())) continue;
-            std::get<0>(info)->counter_.fetch_add(1, std::memory_order_relaxed);
-            hs[i] = std::get<1>(all[i]);
-        }
-        std::atomic_thread_fence(std::memory_order_release);
-        return ::WaitForMultipleObjects(static_cast<DWORD>(i), hs, FALSE, INFINITE) != WAIT_FAILED;
-    }
-
     template <typename F>
     bool wait_if(handle_t h, F&& pred) {
         if (h == invalid()) return false;
-        if (!std::forward<F>(pred)()) return true;
-        counter_.fetch_add(1, std::memory_order_relaxed);
-        std::atomic_thread_fence(std::memory_order_release);
+        {
+            IPC_UNUSED_ auto guard = ipc::detail::unique_lock(lock_);
+            if (!std::forward<F>(pred)()) return true;
+            ++ counter_;
+        }
         return ::WaitForSingleObject(h, INFINITE) == WAIT_OBJECT_0;
     }
 
     void notify(handle_t h) {
         if (h == invalid()) return;
-        for (unsigned k = 0;;) {
-            auto c = counter_.load(std::memory_order_acquire);
-            if (c == 0) return;
-            if (counter_.compare_exchange_weak(c, c - 1, std::memory_order_release)) {
-                break;
-            }
-            ipc::yield(k);
-        }
+        IPC_UNUSED_ auto guard = ipc::detail::unique_lock(lock_);
+        if (counter_ == 0) return;
+        -- counter_;
         ::ReleaseSemaphore(h, 1, NULL);
     }
 
     void broadcast(handle_t h) {
         if (h == invalid()) return;
-        ::ReleaseSemaphore(h, counter_.exchange(0, std::memory_order_acquire), NULL);
+        IPC_UNUSED_ auto guard = ipc::detail::unique_lock(lock_);
+        if (counter_ == 0) return;
+        long all_count = counter_;
+        counter_ = 0;
+        ::ReleaseSemaphore(h, all_count, NULL);
     }
 };
 
diff --git a/src/platform/waiter_wrapper.h b/src/platform/waiter_wrapper.h
index 9af1cde..80b7288 100644
--- a/src/platform/waiter_wrapper.h
+++ b/src/platform/waiter_wrapper.h
@@ -1,10 +1,7 @@
 #pragma once
 
-#include <string>
-#include <tuple>
 #include <type_traits>
-
-#include "pool_alloc.h"
+#include <atomic>
 
 #if defined(WIN64) || defined(_WIN64) || defined(__WIN64__) || \
     defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__) || \
@@ -26,10 +23,6 @@ private:
     waiter_t* w_ = nullptr;
     waiter_t::handle_t h_ = waiter_t::invalid();
 
-    auto to_w_info() {
-        return std::make_tuple(w_, h_);
-    }
-
 public:
     waiter_wrapper() = default;
     explicit waiter_wrapper(waiter_t* w) {
diff --git a/src/prod_cons.h b/src/prod_cons.h
index ac1d17c..e5a2edb 100644
--- a/src/prod_cons.h
+++ b/src/prod_cons.h
@@ -94,7 +94,7 @@ struct prod_cons_impl<wr<relat::multi , relat::multi, trans::unicast>>
     template <typename E, typename F, typename EB>
     bool push(E* /*elems*/, F&& f, EB* elem_start) {
         circ::u2_t cur_ct, nxt_ct;
-        while(1) {
+        while (1) {
             cur_ct = ct_.load(std::memory_order_relaxed);
             if (circ::index_of(nxt_ct = cur_ct + 1) ==
                 circ::index_of(rd_.load(std::memory_order_acquire))) {
@@ -106,7 +106,7 @@ struct prod_cons_impl<wr<relat::multi , relat::multi, trans::unicast>>
             std::this_thread::yield();
         }
         std::forward<F>(f)(elem_start + circ::index_of(cur_ct));
-        while(1) {
+        while (1) {
             auto exp_wt = cur_ct;
             if (wt_.compare_exchange_weak(exp_wt, nxt_ct, std::memory_order_release)) {
                 break;
@@ -145,7 +145,7 @@ struct prod_cons_impl<wr<relat::single, relat::multi, trans::broadcast>> {
         if (conn_cnt == 0) return false;
         auto el = elem_start + circ::index_of(wt_.load(std::memory_order_acquire));
         // check all consumers have finished reading this element
-        while(1) {
+        while (1) {
             rc_t expected = 0;
             if (el->head_.rc_.compare_exchange_weak(
                         expected, static_cast<rc_t>(conn_cnt), std::memory_order_release)) {
@@ -193,7 +193,7 @@ struct prod_cons_impl<wr<relat::multi , relat::multi, trans::broadcast>>
                    nxt_ct = cur_ct + 1;
         auto el = elem_start + circ::index_of(cur_ct);
         // check all consumers have finished reading this element
-        while(1) {
+        while (1) {
             rc_t expected = 0;
             if (el->head_.rc_.compare_exchange_weak(
                         expected, static_cast<rc_t>(conn_cnt), std::memory_order_release)) {
@@ -204,7 +204,7 @@ struct prod_cons_impl<wr<relat::multi , relat::multi, trans::broadcast>>
             if (conn_cnt == 0) return false;
         }
         std::forward<F>(f)(el->data_);
-        while(1) {
+        while (1) {
             auto exp_wt = cur_ct;
             if (wt_.compare_exchange_weak(exp_wt, nxt_ct, std::memory_order_release)) {
                 break;