diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 938cbc5..5b326f7 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -29,6 +29,9 @@ if(UNIX)
     set(EXAMPLE_LIBS ${EXAMPLE_LIBS} ${CMAKE_DL_LIBS})
 endif()
 
+add_executable(concurrency_test concurrency_test.cc)
+target_link_libraries(concurrency_test ${EXAMPLE_LIBS})
+
 add_executable(client_basics client_basics.cc)
 target_link_libraries(client_basics ${EXAMPLE_LIBS})
 
diff --git a/bak/concurrency_test.cc b/examples/concurrency_test.cc
similarity index 69%
rename from bak/concurrency_test.cc
rename to examples/concurrency_test.cc
index 4cb6a51..06262b6 100644
--- a/bak/concurrency_test.cc
+++ b/examples/concurrency_test.cc
@@ -6,18 +6,17 @@
 #include "webcc/client_session.h"
 #include "webcc/logger.h"
 
-// CS Server:
-//   $ concurrency_test 10 http://localhost:55555/patient/query?global_search=ivory&count=200&offset=0&sort_item=birth_date&sort_order=asc
-// GitHub:
-//   $ concurrency_test 10 https://api.github.com/public/events
-
 int main(int argc, const char* argv[]) {
   if (argc < 3) {
     std::cerr << "Usage: concurrency_test <workers> <url>" << std::endl;
+    std::cerr << "E.g.," << std::endl;
+    std::cerr << "  $ concurrency_test 10 https://api.github.com/public/events"
+              << std::endl;
+    std::cerr << "  $ concurrency_test 10 http://localhost:8080/" << std::endl;
     return 1;
   }
 
-  WEBCC_LOG_INIT("", webcc::LOG_CONSOLE_FILE_OVERWRITE);
+  WEBCC_LOG_INIT("", webcc::LOG_CONSOLE);
 
   int workers = std::atoi(argv[1]);
   std::string url = argv[2];
@@ -29,13 +28,17 @@ int main(int argc, const char* argv[]) {
 
   for (int i = 0; i < workers; ++i) {
     threads.emplace_back([&url]() {
+      // NOTE: Each thread has its own client session.
       webcc::ClientSession session;
       session.set_timeout(180);
 
       try {
         LOG_USER("Start");
-        session.Get(url);
+
+        session.Send(webcc::RequestBuilder{}.Get(url)());
+
         LOG_USER("End");
+
       } catch (const webcc::Error& error) {
         LOG_ERRO("Error: %s", error.message().c_str());
       }
diff --git a/examples/hello_world_server.cc b/examples/hello_world_server.cc
index 16b29af..927998a 100644
--- a/examples/hello_world_server.cc
+++ b/examples/hello_world_server.cc
@@ -4,24 +4,47 @@
 
 class HelloView : public webcc::View {
 public:
+  HelloView(int sleep_seconds) : sleep_seconds_(sleep_seconds) {
+  }
+
   webcc::ResponsePtr Handle(webcc::RequestPtr request) override {
+    if (sleep_seconds_ > 0) {
+      std::this_thread::sleep_for(std::chrono::seconds(sleep_seconds_));
+    }
+
     if (request->method() == "GET") {
       return webcc::ResponseBuilder{}.OK().Body("Hello, World!")();
     }
 
     return {};
   }
+
+private:
+  int sleep_seconds_;
 };
 
-int main() {
+int main(int argc, const char* argv[]) {
   WEBCC_LOG_INIT("", webcc::LOG_CONSOLE);
 
+  int workers = 1;
+  int sleep_seconds = 0;
+
+  if (argc > 1) {
+    workers = std::stoi(argv[1]);
+    if (argc > 2) {
+      sleep_seconds = std::stoi(argv[2]);
+    }
+  }
+
+  LOG_USER("Workers: %d", workers);
+  LOG_USER("Sleep seconds: %d", sleep_seconds);
+
   try {
     webcc::Server server(8080);
 
-    server.Route("/", std::make_shared<HelloView>());
+    server.Route("/", std::make_shared<HelloView>(sleep_seconds));
 
-    server.Run();
+    server.Run(workers);
 
   } catch (const std::exception&) {
     return 1;
diff --git a/webcc/body.h b/webcc/body.h
index 1c0a9c4..b4f443d 100644
--- a/webcc/body.h
+++ b/webcc/body.h
@@ -84,6 +84,10 @@ public:
     return data_;
   }
 
+  bool compressed() const {
+    return compressed_;
+  }
+
 #if WEBCC_ENABLE_GZIP
 
   bool Compress() override;
diff --git a/webcc/parser.cc b/webcc/parser.cc
index a8a5383..6c68cdb 100644
--- a/webcc/parser.cc
+++ b/webcc/parser.cc
@@ -55,7 +55,9 @@ bool StringBodyHandler::Finish() {
     return false;
   }
 #else
-  LOG_WARN("Compressed HTTP content remains untouched.");
+  if (body->compressed()) {
+    LOG_WARN("Compressed HTTP content remains untouched.");
+  }
 #endif  // WEBCC_ENABLE_GZIP
 
   message_->SetBody(body, false);