[logger] Resolve thread name once and pass through logging chain

Eliminate redundant xTaskGetCurrentTaskHandle() and pcTaskGetName()
calls on the hot path by resolving the thread name once in log_vprintf_
and passing it through as const char* to all downstream functions.

- Main task fast path passes nullptr (no task handle lookup needed)
- Non-main thread path resolves name once, passes to both ring buffer
  and emergency console fallback
- Unify log_vprintf_non_main_thread_ to single signature across platforms
- Change send_message_thread_safe() on all platforms from TaskHandle_t
  to const char* thread_name
- Add TaskHandle_t overload for get_thread_name_ as primary on
  ESP32/LibreTiny, with no-arg convenience wrapper
- Use std::span<char> for Host/Zephyr get_thread_name_ buffer parameter
- Document Zephyr single-task path thread safety limitation

esphome/components/logger/logger.cpp

@@ -36,8 +36,9 @@ void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const ch
 #endif
 
   // Fast path: main thread, no recursion (99.9% of all logs)
+  // Pass nullptr for thread_name since we already know this is the main task
   if (is_main_task && !this->main_task_recursion_guard_) [[likely]] {
-    this->log_message_to_buffer_and_send_(this->main_task_recursion_guard_, level, tag, line, format, args);
+    this->log_message_to_buffer_and_send_(this->main_task_recursion_guard_, level, tag, line, format, args, nullptr);
     return;
   }
 
@@ -47,21 +48,23 @@ void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const ch
   }
 
   // Non-main thread handling (~0.1% of logs)
+  // Resolve thread name once and pass it through the logging chain.
+  // ESP32/LibreTiny: use TaskHandle_t overload to avoid redundant xTaskGetCurrentTaskHandle()
+  // (we already have the handle from the main task check above).
+  // Host: pass a stack buffer for pthread_getname_np to write into.
 #if defined(USE_ESP32) || defined(USE_LIBRETINY)
-  this->log_vprintf_non_main_thread_(level, tag, line, format, args, current_task);
+  const char *thread_name = get_thread_name_(current_task);
 #else  // USE_HOST
-  this->log_vprintf_non_main_thread_(level, tag, line, format, args);
+  char thread_name_buf[THREAD_NAME_BUF_SIZE];
+  const char *thread_name = this->get_thread_name_(thread_name_buf);
 #endif
+  this->log_vprintf_non_main_thread_(level, tag, line, format, args, thread_name);
 }
 
 // Handles non-main thread logging only
 // Kept separate from hot path to improve instruction cache performance
-#if defined(USE_ESP32) || defined(USE_LIBRETINY)
 void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int line, const char *format, va_list args,
-                                          TaskHandle_t current_task) {
+                                          const char *thread_name) {
-#else  // USE_HOST
-void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int line, const char *format, va_list args) {
-#endif
   // Check if already in recursion for this non-main thread/task
   if (this->is_non_main_task_recursive_()) {
     return;
@@ -73,12 +76,8 @@ void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int li
   bool message_sent = false;
 #ifdef USE_ESPHOME_TASK_LOG_BUFFER
   // For non-main threads/tasks, queue the message for callbacks
-#if defined(USE_ESP32) || defined(USE_LIBRETINY)
   message_sent =
-      this->log_buffer_->send_message_thread_safe(level, tag, static_cast<uint16_t>(line), current_task, format, args);
+      this->log_buffer_->send_message_thread_safe(level, tag, static_cast<uint16_t>(line), thread_name, format, args);
-#else  // USE_HOST
-  message_sent = this->log_buffer_->send_message_thread_safe(level, tag, static_cast<uint16_t>(line), format, args);
-#endif
   if (message_sent) {
     // Enable logger loop to process the buffered message
     // This is safe to call from any context including ISRs
@@ -101,19 +100,27 @@ void Logger::log_vprintf_non_main_thread_(uint8_t level, const char *tag, int li
 #endif
     char console_buffer[MAX_CONSOLE_LOG_MSG_SIZE];  // MUST be stack allocated for thread safety
     LogBuffer buf{console_buffer, MAX_CONSOLE_LOG_MSG_SIZE};
-    this->format_log_to_buffer_with_terminator_(level, tag, line, format, args, buf);
+    this->format_log_to_buffer_with_terminator_(level, tag, line, format, args, buf, thread_name);
     this->write_to_console_(buf);
   }
 
   // RAII guard automatically resets on return
 }
 #else
-// Implementation for all other platforms (single-task, no threading)
+// Implementation for single-task platforms (ESP8266, RP2040, Zephyr)
+// TODO: Zephyr may have multiple threads (work queues, etc.) but uses this single-task path.
+// Logging calls are NOT thread-safe: global_recursion_guard_ is a plain bool and tx_buffer_ has no locking.
+// Not a problem in practice yet since Zephyr has no API support (logs are console-only).
 void HOT Logger::log_vprintf_(uint8_t level, const char *tag, int line, const char *format, va_list args) {  // NOLINT
   if (level > this->level_for(tag) || global_recursion_guard_)
     return;
-
+#ifdef USE_ZEPHYR
-  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args);
+  char tmp[MAX_POINTER_REPRESENTATION];
+  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args,
+                                        this->get_thread_name_(tmp));
+#else  // Other single-task platforms don't have thread names, so pass nullptr
+  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args, nullptr);
+#endif
 }
 #endif  // USE_ESP32 / USE_HOST / USE_LIBRETINY
 
@@ -129,7 +136,7 @@ void Logger::log_vprintf_(uint8_t level, const char *tag, int line, const __Flas
   if (level > this->level_for(tag) || global_recursion_guard_)
     return;
 
-  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args);
+  this->log_message_to_buffer_and_send_(global_recursion_guard_, level, tag, line, format, args, nullptr);
 }
 #endif  // USE_STORE_LOG_STR_IN_FLASH
 

esphome/components/logger/logger.h

@@ -2,6 +2,7 @@
 
 #include <cstdarg>
 #include <map>
+#include <span>
 #include <type_traits>
 #if defined(USE_ESP32) || defined(USE_HOST)
 #include <pthread.h>
@@ -124,6 +125,10 @@ static constexpr uint16_t MAX_HEADER_SIZE = 128;
 // "0x" + 2 hex digits per byte + '\0'
 static constexpr size_t MAX_POINTER_REPRESENTATION = 2 + sizeof(void *) * 2 + 1;
 
+// Stack buffer size for retrieving thread/task names from the OS
+// macOS allows up to 64 bytes, Linux up to 16
+static constexpr size_t THREAD_NAME_BUF_SIZE = 64;
+
 // Buffer wrapper for log formatting functions
 struct LogBuffer {
   char *data;
@@ -408,34 +413,24 @@ class Logger : public Component {
 
 #if defined(USE_ESP32) || defined(USE_HOST) || defined(USE_LIBRETINY)
   // Handles non-main thread logging only (~0.1% of calls)
-#if defined(USE_ESP32) || defined(USE_LIBRETINY)
+  // thread_name is resolved by the caller from the task handle, avoiding redundant lookups
-  // ESP32/LibreTiny: Pass task handle to avoid calling xTaskGetCurrentTaskHandle() twice
   void log_vprintf_non_main_thread_(uint8_t level, const char *tag, int line, const char *format, va_list args,
-                                    TaskHandle_t current_task);
+                                    const char *thread_name);
-#else  // USE_HOST
-  // Host: No task handle parameter needed (not used in send_message_thread_safe)
-  void log_vprintf_non_main_thread_(uint8_t level, const char *tag, int line, const char *format, va_list args);
-#endif
 #endif
   void process_messages_();
   void write_msg_(const char *msg, uint16_t len);
 
   // Format a log message with printf-style arguments and write it to a buffer with header, footer, and null terminator
+  // thread_name: name of the calling thread/task, or nullptr for main task (callers already know which task they're on)
   inline void HOT format_log_to_buffer_with_terminator_(uint8_t level, const char *tag, int line, const char *format,
-                                                        va_list args, LogBuffer &buf) {
+                                                        va_list args, LogBuffer &buf, const char *thread_name) {
-#if defined(USE_ESP32) || defined(USE_LIBRETINY) || defined(USE_HOST)
+    buf.write_header(level, tag, line, thread_name);
-    buf.write_header(level, tag, line, this->get_thread_name_());
-#elif defined(USE_ZEPHYR)
-    char tmp[MAX_POINTER_REPRESENTATION];
-    buf.write_header(level, tag, line, this->get_thread_name_(tmp));
-#else
-    buf.write_header(level, tag, line, nullptr);
-#endif
     buf.format_body(format, args);
   }
 
 #ifdef USE_STORE_LOG_STR_IN_FLASH
   // Format a log message with flash string format and write it to a buffer with header, footer, and null terminator
+  // ESP8266-only (single-task), thread_name is always nullptr
   inline void HOT format_log_to_buffer_with_terminator_P_(uint8_t level, const char *tag, int line,
                                                           const __FlashStringHelper *format, va_list args,
                                                           LogBuffer &buf) {
@@ -466,9 +461,10 @@ class Logger : public Component {
 
   // Helper to format and send a log message to both console and listeners
   // Template handles both const char* (RAM) and __FlashStringHelper* (flash) format strings
+  // thread_name: name of the calling thread/task, or nullptr for main task
   template<typename FormatType>
   inline void HOT log_message_to_buffer_and_send_(bool &recursion_guard, uint8_t level, const char *tag, int line,
-                                                  FormatType format, va_list args) {
+                                                  FormatType format, va_list args, const char *thread_name) {
     RecursionGuard guard(recursion_guard);
     LogBuffer buf{this->tx_buffer_, this->tx_buffer_size_};
 #ifdef USE_STORE_LOG_STR_IN_FLASH
@@ -477,7 +473,7 @@ class Logger : public Component {
     } else
 #endif
     {
-      this->format_log_to_buffer_with_terminator_(level, tag, line, format, args, buf);
+      this->format_log_to_buffer_with_terminator_(level, tag, line, format, args, buf, thread_name);
     }
     this->notify_listeners_(level, tag, buf);
     this->write_log_buffer_to_console_(buf);
@@ -565,37 +561,57 @@ class Logger : public Component {
   bool global_recursion_guard_{false};  // Simple global recursion guard for single-task platforms
 #endif
 
-#if defined(USE_ESP32) || defined(USE_LIBRETINY) || defined(USE_ZEPHYR)
+  // --- get_thread_name_ overloads (per-platform) ---
-  const char *HOT get_thread_name_(
+
-#ifdef USE_ZEPHYR
+#if defined(USE_ESP32) || defined(USE_LIBRETINY)
-      char *buff
+  // Primary overload - takes a task handle directly to avoid redundant xTaskGetCurrentTaskHandle() calls
+  // when the caller already has the handle (e.g. from the main task check in log_vprintf_)
+  const char *get_thread_name_(TaskHandle_t task) {
+    if (task == this->main_task_) {
+      return nullptr;  // Main task
+    }
+#if defined(USE_ESP32)
+    return pcTaskGetName(task);
+#elif defined(USE_LIBRETINY)
+    return pcTaskGetTaskName(task);
 #endif
-  ) {
+  }
-#ifdef USE_ZEPHYR
+
+  // Convenience overload - gets the current task handle and delegates
+  const char *HOT get_thread_name_() { return this->get_thread_name_(xTaskGetCurrentTaskHandle()); }
+
+#elif defined(USE_HOST)
+  // Takes a caller-provided buffer for the thread name (stack-allocated for thread safety)
+  const char *HOT get_thread_name_(std::span<char> buff) {
+    pthread_t current_thread = pthread_self();
+    if (pthread_equal(current_thread, main_thread_)) {
+      return nullptr;  // Main thread
+    }
+    // For non-main threads, get the thread name into the caller-provided buffer
+    if (pthread_getname_np(current_thread, buff.data(), buff.size()) == 0) {
+      return buff.data();
+    }
+    return nullptr;
+  }
+
+#elif defined(USE_ZEPHYR)
+  const char *HOT get_thread_name_(std::span<char> buff) {
     k_tid_t current_task = k_current_get();
-#else
-    TaskHandle_t current_task = xTaskGetCurrentTaskHandle();
-#endif
     if (current_task == main_task_) {
       return nullptr;  // Main task
-    } else {
-#if defined(USE_ESP32)
-      return pcTaskGetName(current_task);
-#elif defined(USE_LIBRETINY)
-      return pcTaskGetTaskName(current_task);
-#elif defined(USE_ZEPHYR)
-      const char *name = k_thread_name_get(current_task);
-      if (name) {
-        // zephyr print task names only if debug component is present
-        return name;
-      }
-      std::snprintf(buff, MAX_POINTER_REPRESENTATION, "%p", current_task);
-      return buff;
-#endif
     }
+    const char *name = k_thread_name_get(current_task);
+    if (name) {
+      // zephyr print task names only if debug component is present
+      return name;
+    }
+    std::snprintf(buff.data(), buff.size(), "%p", current_task);
+    return buff.data();
   }
 #endif
 
+  // --- Non-main task recursion guards (per-platform) ---
+
 #if defined(USE_ESP32) || defined(USE_HOST)
   // RAII guard for non-main task recursion using pthread TLS
   class NonMainTaskRecursionGuard {
@@ -635,22 +651,6 @@ class Logger : public Component {
   inline RecursionGuard make_non_main_task_guard_() { return RecursionGuard(non_main_task_recursion_guard_); }
 #endif
 
-#ifdef USE_HOST
-  const char *HOT get_thread_name_() {
-    pthread_t current_thread = pthread_self();
-    if (pthread_equal(current_thread, main_thread_)) {
-      return nullptr;  // Main thread
-    }
-    // For non-main threads, return the thread name
-    // We store it in thread-local storage to avoid allocation
-    static thread_local char thread_name_buf[32];
-    if (pthread_getname_np(current_thread, thread_name_buf, sizeof(thread_name_buf)) == 0) {
-      return thread_name_buf;
-    }
-    return nullptr;
-  }
-#endif
-
 #if defined(USE_ESP32) || defined(USE_LIBRETINY)
   // Disable loop when task buffer is empty (with USB CDC check on ESP32)
   inline void disable_loop_when_buffer_empty_() {

esphome/components/logger/task_log_buffer_esp32.cpp

@@ -59,7 +59,7 @@ void TaskLogBuffer::release_message_main_loop(void *token) {
   last_processed_counter_ = message_counter_.load(std::memory_order_relaxed);
 }
 
-bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, TaskHandle_t task_handle,
+bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
                                              const char *format, va_list args) {
   // First, calculate the exact length needed using a null buffer (no actual writing)
   va_list args_copy;
@@ -95,7 +95,6 @@ bool TaskLogBuffer::send_message_thread_safe(uint8_t level, const char *tag, uin
   // Store the thread name now instead of waiting until main loop processing
   // This avoids crashes if the task completes or is deleted between when this message
   // is enqueued and when it's processed by the main loop
-  const char *thread_name = pcTaskGetName(task_handle);
   if (thread_name != nullptr) {
     strncpy(msg->thread_name, thread_name, sizeof(msg->thread_name) - 1);
     msg->thread_name[sizeof(msg->thread_name) - 1] = '\0';  // Ensure null termination

esphome/components/logger/task_log_buffer_esp32.h

@@ -58,7 +58,7 @@ class TaskLogBuffer {
   void release_message_main_loop(void *token);
 
   // Thread-safe - send a message to the ring buffer from any thread
-  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, TaskHandle_t task_handle,
+  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
                                 const char *format, va_list args);
 
   // Check if there are messages ready to be processed using an atomic counter for performance

esphome/components/logger/task_log_buffer_host.cpp

@@ -70,8 +70,8 @@ void TaskLogBufferHost::commit_write_slot_(int slot_index) {
   }
 }
 
-bool TaskLogBufferHost::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *format,
+bool TaskLogBufferHost::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
-                                                 va_list args) {
+                                                 const char *format, va_list args) {
   // Acquire a slot
   int slot_index = this->acquire_write_slot_();
   if (slot_index < 0) {
@@ -85,11 +85,9 @@ bool TaskLogBufferHost::send_message_thread_safe(uint8_t level, const char *tag,
   msg.tag = tag;
   msg.line = line;
 
-  // Get thread name using pthread
+  // Store the thread name now to avoid crashes if thread exits before processing
-  char thread_name_buf[LogMessage::MAX_THREAD_NAME_SIZE];
+  if (thread_name != nullptr) {
-  // pthread_getname_np works the same on Linux and macOS
+    strncpy(msg.thread_name, thread_name, sizeof(msg.thread_name) - 1);
-  if (pthread_getname_np(pthread_self(), thread_name_buf, sizeof(thread_name_buf)) == 0) {
-    strncpy(msg.thread_name, thread_name_buf, sizeof(msg.thread_name) - 1);
     msg.thread_name[sizeof(msg.thread_name) - 1] = '\0';
   } else {
     msg.thread_name[0] = '\0';

esphome/components/logger/task_log_buffer_host.h

@@ -86,7 +86,8 @@ class TaskLogBufferHost {
 
   // Thread-safe - send a message to the buffer from any thread
   // Returns true if message was queued, false if buffer is full
-  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *format, va_list args);
+  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
+                                const char *format, va_list args);
 
   // Check if there are messages ready to be processed
   inline bool HOT has_messages() const {

esphome/components/logger/task_log_buffer_libretiny.cpp

@@ -101,7 +101,7 @@ void TaskLogBufferLibreTiny::release_message_main_loop() {
 }
 
 bool TaskLogBufferLibreTiny::send_message_thread_safe(uint8_t level, const char *tag, uint16_t line,
-                                                      TaskHandle_t task_handle, const char *format, va_list args) {
+                                                      const char *thread_name, const char *format, va_list args) {
   // First, calculate the exact length needed using a null buffer (no actual writing)
   va_list args_copy;
   va_copy(args_copy, args);
@@ -162,7 +162,6 @@ bool TaskLogBufferLibreTiny::send_message_thread_safe(uint8_t level, const char
   msg->line = line;
 
   // Store the thread name now to avoid crashes if task is deleted before processing
-  const char *thread_name = pcTaskGetTaskName(task_handle);
   if (thread_name != nullptr) {
     strncpy(msg->thread_name, thread_name, sizeof(msg->thread_name) - 1);
     msg->thread_name[sizeof(msg->thread_name) - 1] = '\0';

esphome/components/logger/task_log_buffer_libretiny.h

@@ -70,7 +70,7 @@ class TaskLogBufferLibreTiny {
   void release_message_main_loop();
 
   // Thread-safe - send a message to the buffer from any thread
-  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, TaskHandle_t task_handle,
+  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
                                 const char *format, va_list args);
 
   // Fast check using volatile counter - no lock needed