添加内存占用的测试代码

README.md

 librf有以下特点：
 
  *   1.基于C++17提案'Stackless Resumable Functions'编写的非对称stackless协程库，可以以同步的方式编写简单的代码，同时获得异步的性能
- *   2.理论上支持海量协程, 创建100万个协程只需使用<待测试>物理内存
+ *   2.理论上支持海量协程, 创建100万个协程只需使用<820M>物理内存
  *   3.提供协程锁(mutex), 定时器, channel等特性, 帮助用户更加容易地编写程序 
- *   4.可以很好的跟asio,libuv等库结合，能更现有的callback范式的异步/延迟代码结合
+ *   4.可以很好的跟asio,libuv等库结合，能跟现有的callback范式的异步/延迟代码很好的结合
  *   5.目前还处于实验状态，不对今后正式的C++ Coroutines支持有任何正式的承诺
  
  *   如果你发现了任何bug、有好的建议、或使用上有不明之处，可以提交到issue，也可以直接联系作者:

benchmark/benchmark_async_mem.cpp

+
+#include <chrono>
+#include <iostream>
+#include <string>
+#include <conio.h>
+#include <thread>
+
+#include "librf.h"
+
+const size_t N = 1000000;
+
+void resumable_main_benchmark_mem()
+{
+	using namespace std::chrono;
+
+	for (size_t i = 0; i < N; ++i)
+	{
+		GO
+		{
+			for(size_t k = 0; k<100; ++k)
+				co_await resumef::sleep_for(10s);
+		};
+	}
+
+	resumef::g_scheduler.run_until_notask();
+}

tutorial/test_async_cb.cpp

 
 	resumef::promise_t<int64_t> awaitable;
 
-	std::thread([val, st = awaitable._state->lock()]
+	std::thread([val, st = awaitable._state]
 	{
 		std::this_thread::sleep_for(500ms);
 		st->set_value(val * val);
-		st->unlock();
 	}).detach();
 
 	return awaitable.get_future();

vs_proj/librf.cpp

 extern void resumable_main_channel();
 extern void resumable_main_cb();
 
+extern void resumable_main_benchmark_mem();
+
 int main(int argc, const char * argv[])
 {
+	resumable_main_benchmark_mem();
+	return 0;
+
 	resumable_main_yield_return();
 	resumable_main_timer();
 	resumable_main_suspend_always();

vs_proj/librf.vcxproj

       <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>..\librf;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <AdditionalOptions>/await /stdlast++ %(AdditionalOptions)</AdditionalOptions>
+      <AdditionalOptions>/await /std:c++latest </AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Console</SubSystem>
       <PreprocessorDefinitions>_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>..\librf;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <AdditionalOptions>/await /std:c++latest %(AdditionalOptions)</AdditionalOptions>
+      <AdditionalOptions>/await /std:c++latest </AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Console</SubSystem>
       <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>..\librf;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <AdditionalOptions>/await /stdlast++ %(AdditionalOptions)</AdditionalOptions>
+      <AdditionalOptions>/await /std:c++latest </AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Console</SubSystem>
       <PreprocessorDefinitions>NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>..\librf;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <AdditionalOptions>/await /stdlast++ %(AdditionalOptions)</AdditionalOptions>
+      <AdditionalOptions>/await /std:c++latest </AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Console</SubSystem>
     </Link>
   </ItemDefinitionGroup>
   <ItemGroup>
+    <ClCompile Include="..\benchmark\benchmark_async_mem.cpp" />
     <ClCompile Include="..\librf\src\event.cpp" />
     <ClCompile Include="..\librf\src\mutex.cpp" />
     <ClCompile Include="..\librf\src\rf_task.cpp" />

vs_proj/librf.vcxproj.filters

     <Filter Include="tutorial">
       <UniqueIdentifier>{d82e4930-c171-4b70-9ebb-cdec7218ff9c}</UniqueIdentifier>
     </Filter>
+    <Filter Include="benchmark">
+      <UniqueIdentifier>{0fd1274a-193b-4d6a-b19e-58db935ed5c6}</UniqueIdentifier>
+    </Filter>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="librf.cpp">
     <ClCompile Include="..\tutorial\test_async_yield_return.cpp">
       <Filter>tutorial</Filter>
     </ClCompile>
+    <ClCompile Include="..\benchmark\benchmark_async_mem.cpp">
+      <Filter>benchmark</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="..\librf\librf.h">