diff --git a/.github/workflows/clang-format.yml b/.github/workflows/clang-format.yml
index b6875aae0..dfeaf8ed7 100644
--- a/.github/workflows/clang-format.yml
+++ b/.github/workflows/clang-format.yml
@@ -21,10 +21,12 @@ jobs:
         run: pip install clang-format
       - name: check-diff
         run: |
-          diff=`git-clang-format --diff HEAD^`
-          if ! [[ "$diff" = "no modified files to format" || "$diff" = "clang-format did not modify any files" ]]; then
-              echo "The diff you sent is not formatted correctly."
-              echo "The suggested format is"
-              echo "$diff"
-              exit 1
-          fi
+            diff=$(git-clang-format --diff HEAD^) || true
+            if [ -n "$diff" ] \
+              && [ "$diff" != "no modified files to format" ] \
+              && [ "$diff" != "clang-format did not modify any files" ]; then
+                echo "The diff you sent is not formatted correctly."
+                echo "The suggested format is:"
+                echo "$diff"
+                exit 1
+            fi
diff --git a/include/ylt/easylog.hpp b/include/ylt/easylog.hpp
index f0ccfd3b6..513798b94 100644
--- a/include/ylt/easylog.hpp
+++ b/include/ylt/easylog.hpp
@@ -38,6 +38,8 @@
 
 #include <ylt/util/b_stacktrace.h>
 
+#include <memory>
+
 #include "easylog/appender.hpp"
 
 namespace easylog {
@@ -100,10 +102,10 @@ class logger {
             bool flush_every_time,
             std::chrono::milliseconds log_sample_interval = {},
             std::chrono::milliseconds log_sample_duartion = {}) {
-    static appender appender(filename, async, enable_console, max_file_size,
-                             max_files, flush_every_time);
+    appender_ =
+        std::make_unique<appender>(filename, async, enable_console,
+                                   max_file_size, max_files, flush_every_time);
     async_ = async;
-    appender_ = &appender;
     min_severity_ = min_severity;
     enable_console_ = enable_console;
     log_sample_interval_ = log_sample_interval;
@@ -128,7 +130,11 @@ class logger {
     appenders_.emplace_back(std::move(fn));
   }
 
-  void stop_async_log() { appender_->stop(); }
+  void stop_async_log() {
+    if (appender_) {
+      appender_->stop();
+    }
+  }
 
   // set and get
   void set_min_severity(Severity severity) { min_severity_ = severity; }
@@ -157,14 +163,13 @@ class logger {
 
  private:
   logger() {
-    static appender appender{};
-    appender.start_thread();
-    appender.enable_console(true);
+    appender_ = std::make_unique<appender>();
+    appender_->enable_console(true);
     async_ = true;
-    appender_ = &appender;
   }
 
-  logger(const logger &) = default;
+  logger(const logger&) = delete;
+  logger& operator=(const logger&) = delete;
 
   void append_record(record_t record) { appender_->write(std::move(record)); }
 
@@ -190,7 +195,7 @@ class logger {
   std::atomic<std::chrono::milliseconds> log_sample_interval_;
   std::atomic<std::chrono::milliseconds> log_sample_duration_;
   std::chrono::system_clock::time_point init_time_{};
-  appender *appender_ = nullptr;
+  std::unique_ptr<appender> appender_ = nullptr;
   std::vector<std::function<void(record_t &record)>> appenders_;
   inline static std::atomic<bool> has_destruct_ = false;
 };
diff --git a/include/ylt/easylog/appender.hpp b/include/ylt/easylog/appender.hpp
index 359949366..e0b71d3ba 100644
--- a/include/ylt/easylog/appender.hpp
+++ b/include/ylt/easylog/appender.hpp
@@ -158,8 +158,6 @@ class appender {
 
     buf[0] = '[';
     auto [ptr, ec] = std::to_chars(buf + 1, buf + 21, tid);
-    buf[22] = ']';
-    buf[23] = ' ';
     last_tid = tid;
     last_len = ptr - buf;
     buf[last_len++] = ']';
@@ -295,29 +293,29 @@ class appender {
     std::lock_guard guard(mtx_);
     if (file_.is_open()) {
       file_.flush();
-      file_.sync_with_stdio();
     }
   }
 
   void stop() {
-    std::lock_guard guard(mtx_);
     if (!write_thd_.joinable()) {
       return;
     }
 
-    if (stop_) {
-      return;
+    {
+      std::lock_guard guard(que_mtx_);
+      if (!stop_) {
+        stop_ = true;
+        cnd_.notify_one();
+      }
     }
-    stop_ = true;
-    cnd_.notify_one();
-  }
 
-  ~appender() {
-    stop();
-    if (write_thd_.joinable())
+    if (write_thd_.joinable()) {
       write_thd_.join();
+    }
   }
 
+  ~appender() { stop(); }
+
  private:
   void open_log_file() {
     file_size_ = 0;
@@ -347,6 +345,9 @@ class appender {
           file_size_ += BOM_STR.size();
         }
       }
+      else {
+        file_size_ = file_size;
+      }
     }
   }
 
diff --git a/include/ylt/standalone/cinatra/coro_http_client.hpp b/include/ylt/standalone/cinatra/coro_http_client.hpp
index e9e50214f..dae0d053e 100644
--- a/include/ylt/standalone/cinatra/coro_http_client.hpp
+++ b/include/ylt/standalone/cinatra/coro_http_client.hpp
@@ -674,9 +674,13 @@ class coro_http_client : public std::enable_shared_from_this<coro_http_client> {
     timer_guard(coro_http_client *self,
                 std::chrono::steady_clock::duration duration, std::string msg)
         : self(self), dur_(duration) {
+      if (duration.count() == 0) {
+        // Zero duration means immediate timeout.
+        self->socket_->is_timeout_ = true;
+        return;
+      }
       self->socket_->is_timeout_ = false;
-
-      if (duration.count() >= 0) {
+      if (duration.count() > 0) {
         self->timeout(self->timer_, duration, std::move(msg))
             .start([](auto &&) {
             });
@@ -1196,6 +1200,9 @@ class coro_http_client : public std::enable_shared_from_this<coro_http_client> {
     }
 
     auto time_guard = timer_guard(this, req_timeout_duration_, "request timer");
+    if (socket_->is_timeout_) {
+      co_return resp_data{make_error_code(http_errc::request_timeout), 404};
+    }
     std::tie(ec, size) = co_await async_write(asio::buffer(header_str));
     if (ec) {
       handle_upload_timeout_error(ec);
@@ -1393,6 +1400,10 @@ class coro_http_client : public std::enable_shared_from_this<coro_http_client> {
       CINATRA_LOG_DEBUG << req_head_str;
 #endif
       auto guard = timer_guard(this, req_timeout_duration_, "request timer");
+      if (socket_->is_timeout_) {
+        ec = make_error_code(http_errc::request_timeout);
+        break;
+      }
       if (has_body) {
         std::tie(ec, size) = co_await async_write(vec);
       }
@@ -2249,7 +2260,9 @@ class coro_http_client : public std::enable_shared_from_this<coro_http_client> {
     if (socket_->has_closed_) {
       auto time_out_guard =
           timer_guard(this, conn_timeout_duration_, "connect timer");
-      socket_->is_timeout_ = false;
+      if (socket_->is_timeout_) {
+        co_return resp_data{make_error_code(http_errc::connect_timeout), 404};
+      }
       host_ = proxy_host_.empty() ? u.get_host() : proxy_host_;
       port_ = proxy_port_.empty() ? u.get_port() : proxy_port_;
       if (eps->empty()) {
@@ -2278,6 +2291,9 @@ class coro_http_client : public std::enable_shared_from_this<coro_http_client> {
           << ":" << std::to_string((*eps)[0].port());
       std::error_code ec;
       if (ec = co_await coro_io::async_connect(socket_->impl_, *eps); ec) {
+        if (socket_->is_timeout_) {
+          ec = make_error_code(http_errc::connect_timeout);
+        }
         co_return resp_data{ec, 404};
       }
 #ifdef INJECT_FOR_HTTP_CLIENT_TEST
diff --git a/include/ylt/standalone/cinatra/session_manager.hpp b/include/ylt/standalone/cinatra/session_manager.hpp
index 6ec39cc2c..3fd00e337 100644
--- a/include/ylt/standalone/cinatra/session_manager.hpp
+++ b/include/ylt/standalone/cinatra/session_manager.hpp
@@ -61,6 +61,9 @@ class session_manager {
 
   void start_check_session_timer() {
     std::lock_guard lock(timer_mtx_);
+    if (stop_timer_ || !check_session_timer_) {
+      return;
+    }
     std::weak_ptr<asio::steady_timer> timer = check_session_timer_;
     check_session_timer_->expires_after(check_session_duration_);
     check_session_timer_->async_wait([this, timer](auto ec) {
@@ -69,12 +72,26 @@ class session_manager {
         return;
       }
 
-      if (ec || stop_timer_) {
+      if (ec) {
         return;
       }
 
+      {
+        std::lock_guard lock(shutdown_mtx_);
+        if (stop_timer_) {
+          return;
+        }
+        ++active_callbacks_;
+      }
+
       remove_expire_session();
       start_check_session_timer();
+
+      {
+        std::lock_guard lock(shutdown_mtx_);
+        --active_callbacks_;
+      }
+      shutdown_cv_.notify_all();
     });
   }
 
@@ -89,9 +106,32 @@ class session_manager {
     start_check_session_timer();
   }
 
-  void stop_timer() { stop_timer_ = true; }
+  void stop_timer() {
+    std::lock_guard lock(shutdown_mtx_);
+    stop_timer_ = true;
+  }
 
  private:
+  ~session_manager() {
+    {
+      std::lock_guard lock(timer_mtx_);
+      check_session_timer_->cancel();
+      check_session_timer_.reset();
+    }
+    {
+      std::lock_guard lock(shutdown_mtx_);
+      stop_timer_ = true;
+    }
+    {
+      std::unique_lock lock(shutdown_mtx_);
+      shutdown_cv_.wait(lock, [this] {
+        return active_callbacks_ == 0;
+      });
+    }
+    std::lock_guard lock(mtx_);
+    map_.clear();
+  }
+
   session_manager()
       : check_session_timer_(std::make_shared<asio::steady_timer>(
             coro_io::get_global_executor()->get_asio_executor())) {
@@ -111,6 +151,10 @@ class session_manager {
   std::shared_ptr<asio::steady_timer> check_session_timer_;
   std::atomic<std::chrono::steady_clock::duration> check_session_duration_ = {
       std::chrono::seconds(15)};
+
+  std::mutex shutdown_mtx_;
+  std::condition_variable shutdown_cv_;
+  int active_callbacks_ = 0;
 };
 
 }  // namespace cinatra
\ No newline at end of file
diff --git a/src/coro_http/tests/test_cinatra.cpp b/src/coro_http/tests/test_cinatra.cpp
index f64ea4059..3ae22faa8 100644
--- a/src/coro_http/tests/test_cinatra.cpp
+++ b/src/coro_http/tests/test_cinatra.cpp
@@ -2754,6 +2754,89 @@ TEST_CASE("test coro_http_client chunked upload and download") {
   }
 }
 
+TEST_CASE("test zero duration timeout returns correct error codes") {
+  // 验证 set_conn_timeout(0ms) 和 set_req_timeout(0ms)
+  // 能确定性地返回正确错误码， 不依赖与异步操作的竞争结果。
+  coro_http_server server(1, 8091);
+  server.set_http_handler<cinatra::GET, cinatra::PUT, cinatra::POST>(
+      "/timeout_test", [](coro_http_request&, coro_http_response& resp) {
+        resp.set_status_and_content(status_type::ok, "ok");
+      });
+  server.async_start();
+
+  std::string uri = "http://127.0.0.1:8091/timeout_test";
+  create_file("timeout_test.txt", 1024);
+
+  // --- conn_timeout(0ms) 场景 ---
+
+  {
+    // async_upload_chunked：0ms 连接超时应返回 connect_timeout
+    coro_http_client client{};
+    client.set_conn_timeout(0ms);
+    auto result = async_simple::coro::syncAwait(client.async_upload_chunked(
+        uri, http_method::PUT, "timeout_test.txt"sv));
+    CHECK(result.status != 200);
+    CHECK(result.net_err == http_errc::connect_timeout);
+  }
+
+  {
+    // async_upload：0ms 连接超时应返回 connect_timeout
+    coro_http_client client{};
+    client.set_conn_timeout(0ms);
+    auto result = async_simple::coro::syncAwait(
+        client.async_upload(uri, http_method::PUT, "timeout_test.txt"sv));
+    CHECK(result.status != 200);
+    CHECK(result.net_err == http_errc::connect_timeout);
+  }
+
+  {
+    // async_request（GET）：0ms 连接超时应返回 connect_timeout
+    coro_http_client client{};
+    client.set_conn_timeout(0ms);
+    auto result = async_simple::coro::syncAwait(client.async_get(uri));
+    CHECK(result.status != 200);
+    CHECK(result.net_err == http_errc::connect_timeout);
+  }
+
+  // --- req_timeout(0ms) 场景（连接正常，请求立即超时） ---
+
+  {
+    // async_upload_chunked：0ms 请求超时应返回 request_timeout
+    coro_http_client client{};
+    client.set_conn_timeout(500ms);
+    client.set_req_timeout(0ms);
+    client.add_header("filename", "timeout_test.txt");
+    auto result = async_simple::coro::syncAwait(client.async_upload_chunked(
+        uri, http_method::PUT, "timeout_test.txt"sv));
+    CHECK(result.status != 200);
+    CHECK(result.net_err == http_errc::request_timeout);
+  }
+
+  {
+    // async_upload：0ms 请求超时应返回 request_timeout
+    coro_http_client client{};
+    client.set_conn_timeout(500ms);
+    client.set_req_timeout(0ms);
+    auto result = async_simple::coro::syncAwait(
+        client.async_upload(uri, http_method::PUT, "timeout_test.txt"sv));
+    CHECK(result.status != 200);
+    CHECK(result.net_err == http_errc::request_timeout);
+  }
+
+  {
+    // async_request（GET）：0ms 请求超时应返回 request_timeout
+    coro_http_client client{};
+    client.set_conn_timeout(500ms);
+    client.set_req_timeout(0ms);
+    auto result = async_simple::coro::syncAwait(client.async_get(uri));
+    CHECK(result.status != 200);
+    CHECK(result.net_err == http_errc::request_timeout);
+  }
+
+  std::error_code ignore_ec;
+  std::filesystem::remove("timeout_test.txt", ignore_ec);
+}
+
 TEST_CASE("test coro_http_client get") {
   coro_http_client client{};
   client.set_conn_timeout(1s);