diff --git a/include/libconcur/concurrent.h b/include/libconcur/concurrent.h
index 2e3d900..f759533 100644
--- a/include/libconcur/concurrent.h
+++ b/include/libconcur/concurrent.h
@@ -95,14 +95,14 @@ struct producer<trans::unicast, relation::single> {
     auto f_ct  = elem.get_flag();
     /// @remark Verify index.
     if ((f_ct != state::invalid_value) && 
-        (f_ct != static_cast<state::flag_t>(w_idx))) {
+        (f_ct != w_idx)) {
       return false; // full
     }
     /// @remark Get a valid index and iterate backwards.
     ctx.w_idx += 1;
     /// @remark Set data & flag.
     elem.set_data(std::forward<U>(src));
-    elem.set_flag(static_cast<state::flag_t>(~w_idx));
+    elem.set_flag(static_cast<index_t>(~w_idx));
     return true;
   }
 };
@@ -131,12 +131,12 @@ struct producer<trans::unicast, relation::multi> {
         return false; // full
       }
       /// @remark Get a valid index and iterate backwards.
-      if (!ctx.w_idx.compare_exchange_week(w_idx, w_idx + 1, std::memory_order_acq_rel)) {
+      if (!ctx.w_idx.compare_exchange_weak(w_idx, w_idx + 1, std::memory_order_acq_rel)) {
         continue;
       }
       /// @remark Set data & flag.
       elem.set_data(std::forward<U>(src));
-      elem.set_flag(~w_idx);
+      elem.set_flag(static_cast<index_t>(~w_idx));
       return true;
     }
   }
@@ -160,7 +160,7 @@ struct consumer<trans::unicast, relation::single> {
     auto &elem = elems[r_cur];
     auto f_ct  = elem.get_flag();
     /// @remark Verify index.
-    if (f_ct != ~r_idx) {
+    if (f_ct != static_cast<index_t>(~r_idx)) {
       return false; // empty
     }
     /// @remark Get a valid index and iterate backwards.
@@ -191,11 +191,11 @@ struct consumer<trans::unicast, relation::multi> {
       auto &elem = elems[r_cur];
       auto f_ct  = elem.get_flag();
       /// @remark Verify index.
-      if (f_ct != ~r_idx) {
+      if (f_ct != static_cast<index_t>(~r_idx)) {
         return false; // empty
       }
       /// @remark Get a valid index and iterate backwards.
-      if (!ctx.r_idx.compare_exchange_week(r_idx, r_idx + 1, std::memory_order_acq_rel)) {
+      if (!ctx.r_idx.compare_exchange_weak(r_idx, r_idx + 1, std::memory_order_acq_rel)) {
         continue;
       }
       /// @remark Get data & set flag.
@@ -240,7 +240,7 @@ struct consumer<trans::broadcast, relation::multi> {
 template <typename TransModT, typename ProdModT, typename ConsModT>
 struct prod_cons : producer<TransModT, ProdModT>
                  , consumer<TransModT, ConsModT> {
-  
+
   /// @brief Mixing producer and consumer context definitions.
   struct context : producer<TransModT, ProdModT>::context_impl
                  , consumer<TransModT, ConsModT>::context_impl {
@@ -249,6 +249,10 @@ struct prod_cons : producer<TransModT, ProdModT>
     constexpr context(index_t cs) noexcept
       : circ_size(cs) {}
 
+    template <typename T>
+    constexpr context(::LIBIMP_::span<element<T>> elems) noexcept
+      : circ_size(static_cast<index_t>(elems.size())) {}
+
     constexpr bool valid() const noexcept {
       /// @remark circ_size must be a power of two.
       return (circ_size > 1) && ((circ_size & (circ_size - 1)) == 0);
diff --git a/include/libimp/nameof.h b/include/libimp/nameof.h
new file mode 100644
index 0000000..84a1dbc
--- /dev/null
+++ b/include/libimp/nameof.h
@@ -0,0 +1,40 @@
+/**
+ * @file libimp/nameof.h
+ * @author mutouyun (orz@orzz.org)
+ * @brief Gets the name string of a type.
+ * @date 2022-11-26
+ */
+#pragma once
+
+#include <typeinfo>
+#include <string>
+#include <cstring>
+
+#include "libimp/def.h"
+#include "libimp/span.h"
+
+LIBIMP_NAMESPACE_BEG_
+
+/**
+ * @brief The conventional way to obtain demangled symbol name.
+ * @see https://www.boost.org/doc/libs/1_80_0/libs/core/doc/html/core/demangle.html
+ * 
+ * @param name the mangled name
+ * @return std::string a human-readable demangled type name
+ */
+std::string demangle(span<char const> name) noexcept;
+
+/**
+ * @brief Returns an implementation defined string containing the name of the type.
+ * @see https://en.cppreference.com/w/cpp/types/type_info/name
+ * 
+ * @tparam T a type
+ * @return std::string a human-readable demangled type name
+ */
+template <typename T>
+std::string nameof() noexcept {
+  auto c_str_name = typeid(T).name();
+  return demangle({c_str_name, std::strlen(c_str_name)});
+}
+
+LIBIMP_NAMESPACE_END_
diff --git a/src/libimp/nameof.cpp b/src/libimp/nameof.cpp
new file mode 100644
index 0000000..ef6a452
--- /dev/null
+++ b/src/libimp/nameof.cpp
@@ -0,0 +1,7 @@
+
+#include "libimp/detect_plat.h"
+#if defined(LIBIMP_CC_GNUC)
+# include "libimp/platform/gnuc/demangle.h"
+#else
+# include "libimp/platform/win/demangle.h"
+#endif
diff --git a/src/libimp/platform/gnuc/demangle.h b/src/libimp/platform/gnuc/demangle.h
new file mode 100644
index 0000000..e1ef540
--- /dev/null
+++ b/src/libimp/platform/gnuc/demangle.h
@@ -0,0 +1,41 @@
+/**
+ * @file libimp/platform/gnuc/demangle.h
+ * @author mutouyun (orz@orzz.org)
+ */
+#pragma once
+
+#include <cxxabi.h> // abi::__cxa_demangle
+
+#include <cstdlib>  // std::malloc
+
+#include "libimp/def.h"
+#include "libimp/nameof.h"
+#include "libimp/log.h"
+
+LIBIMP_NAMESPACE_BEG_
+
+/**
+ * @brief The conventional way to obtain demangled symbol name.
+ * @see https://www.boost.org/doc/libs/1_80_0/libs/core/doc/html/core/demangle.html
+ * 
+ * @param name the mangled name
+ * @return std::string a human-readable demangled type name
+ */
+std::string demangle(span<char const> name) noexcept {
+  LIBIMP_LOG_();
+  /// @see https://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-html-USERS-4.3/a01696.html
+  std::size_t sz = name.size() + 1;
+  char *buffer = static_cast<char *>(std::malloc(sz));
+  int status = 0;
+  char *realname = abi::__cxa_demangle(name.data(), buffer, &sz, &status);
+  if (realname == nullptr) {
+    log.error("failed: abi::__cxa_demangle(sz = {}), status = {}", sz, status);
+    std::free(buffer);
+    return {};
+  }
+  std::string demangled(realname, sz);
+  std::free(realname);
+  return demangled;
+}
+
+LIBIMP_NAMESPACE_END_
diff --git a/src/libimp/platform/win/demangle.h b/src/libimp/platform/win/demangle.h
new file mode 100644
index 0000000..a8468a6
--- /dev/null
+++ b/src/libimp/platform/win/demangle.h
@@ -0,0 +1,16 @@
+/**
+ * @file libimp/platform/win/demangle.h
+ * @author mutouyun (orz@orzz.org)
+ */
+#pragma once
+
+#include "libimp/def.h"
+#include "libimp/nameof.h"
+
+LIBIMP_NAMESPACE_BEG_
+
+std::string demangle(span<char const> name) noexcept {
+  return std::string(name.data(), name.size());
+}
+
+LIBIMP_NAMESPACE_END_
diff --git a/src/libimp/system.cpp b/src/libimp/system.cpp
index 2c1296b..b5b73dc 100644
--- a/src/libimp/system.cpp
+++ b/src/libimp/system.cpp
@@ -1,12 +1,13 @@
-#include "libimp/detect_plat.h"
-#if defined(LIBIMP_OS_WIN)
-#include "libimp/platform/win/system.h"
-#else
-#include "libimp/platform/posix/system.h"
-#endif
 
 #include "fmt/format.h"
 
+#include "libimp/detect_plat.h"
+#if defined(LIBIMP_OS_WIN)
+# include "libimp/platform/win/system.h"
+#else
+# include "libimp/platform/posix/system.h"
+#endif
+
 LIBIMP_NAMESPACE_BEG_
 namespace sys {
 
diff --git a/src/libipc/shm.cpp b/src/libipc/shm.cpp
index 5804193..5cc1843 100644
--- a/src/libipc/shm.cpp
+++ b/src/libipc/shm.cpp
@@ -5,9 +5,9 @@
 
 #include "libimp/detect_plat.h"
 #if defined(LIBIMP_OS_WIN)
-#include "libipc/platform/win/shm_impl.h"
+# include "libipc/platform/win/shm_impl.h"
 #else
-#include "libipc/platform/posix/shm_impl.h"
+# include "libipc/platform/posix/shm_impl.h"
 #endif
 
 LIBIPC_NAMESPACE_BEG_
diff --git a/test/concur/test_concur_concurrent.cpp b/test/concur/test_concur_concurrent.cpp
index e07a3f1..f243f1e 100644
--- a/test/concur/test_concur_concurrent.cpp
+++ b/test/concur/test_concur_concurrent.cpp
@@ -1,10 +1,17 @@
 
 #include <iostream>
+#include <thread>
+#include <vector>
+#include <atomic>
+#include <typeinfo>
 #include <cstddef>
 
 #include "gtest/gtest.h"
 
 #include "libconcur/concurrent.h"
+#include "libimp/countof.h"
+#include "libimp/log.h"
+#include "libimp/nameof.h"
 
 TEST(concurrent, cache_line_size) {
   std::cout << concur::cache_line_size << "\n";
@@ -79,4 +86,75 @@ TEST(concurrent, trunc_index) {
   EXPECT_EQ(concur::trunc_index(context{2147483648u}, 16), 16);
   EXPECT_EQ(concur::trunc_index(context{2147483648u}, 111), 111);
   EXPECT_EQ(concur::trunc_index(context{2147483648u}, -1), 2147483647);
+}
+
+namespace {
+
+template <typename PC>
+void test_concur(std::size_t np, std::size_t nc, std::size_t k) {
+  LIBIMP_LOG_();
+  log.info("\n\tStart with: {}, {} producers, {} consumers...", imp::nameof<PC>(), np, nc);
+
+  constexpr static std::uint32_t loop_size = 100'0000;
+
+  concur::element<std::uint64_t> circ[32] {};
+  PC pc;
+  PC::context ctx {imp::make_span(circ)};
+  ASSERT_TRUE(ctx.valid());
+
+  std::atomic<std::uint64_t> sum {0};
+  std::atomic<std::size_t> running {np};
+
+  auto prod_call = [&](std::size_t n) {
+    for (std::uint32_t i = 1; i <= loop_size; ++i) {
+      std::this_thread::yield();
+      while (!pc.enqueue(imp::make_span(circ), ctx, i)) {
+        std::this_thread::yield();
+      }
+      if (i % (loop_size / 10) == 0) {
+        log.info("[{}] put count: {}", n, i);
+      }
+    }
+    --running;
+  };
+  auto cons_call = [&] {
+    for (;;) {
+      std::this_thread::yield();
+      std::uint64_t i;
+      while (!pc.dequeue(imp::make_span(circ), ctx, i)) {
+        if (running == 0) return;
+        std::this_thread::yield();
+      }
+      sum += i;
+    }
+  };
+
+  std::vector<std::thread> prods(np);
+  for (std::size_t n = 0; n < np; ++n) prods[n] = std::thread(prod_call, n);
+  std::vector<std::thread> conss(nc);
+  for (auto &c : conss) c = std::thread(cons_call);
+
+  for (auto &p : prods) p.join();
+  for (auto &c : conss) c.join();
+
+  EXPECT_EQ(sum, k * np * (loop_size * std::uint64_t(loop_size + 1)) / 2);
+}
+
+} // namespace
+
+TEST(concurrent, prod_cons) {
+  using namespace concur;
+
+  test_concur<prod_cons<trans::unicast, relation::single, relation::single>>(1, 1, 1);
+  test_concur<prod_cons<trans::unicast, relation::single, relation::multi >>(1, 1, 1);
+  test_concur<prod_cons<trans::unicast, relation::multi , relation::single>>(1, 1, 1);
+  test_concur<prod_cons<trans::unicast, relation::multi , relation::multi >>(1, 1, 1);
+
+  test_concur<prod_cons<trans::unicast, relation::multi , relation::single>>(8, 1, 1);
+  test_concur<prod_cons<trans::unicast, relation::multi , relation::multi >>(8, 1, 1);
+
+  test_concur<prod_cons<trans::unicast, relation::single, relation::multi >>(1, 8, 1);
+  test_concur<prod_cons<trans::unicast, relation::multi , relation::multi >>(1, 8, 1);
+
+  test_concur<prod_cons<trans::unicast, relation::multi , relation::multi >>(8, 8, 1);
 }
\ No newline at end of file