klippy: set posix thread names (pthread_setname_np)

klippy/chelper/serialqueue.c

@@ -12,6 +12,7 @@
 // clock times, prioritizes commands, and handles retransmissions.  A
 // background thread is launched to do this work and minimize latency.
 
+#define _GNU_SOURCE
 #include <linux/can.h> // // struct can_frame
 #include <math.h> // fabs
 #include <pthread.h> // pthread_mutex_lock
@@ -674,6 +675,9 @@ serialqueue_alloc(int serial_fd, char serial_fd_type, int client_id)
     if (ret)
         goto fail;
     ret = pthread_create(&sq->tid, NULL, background_thread, sq);
+    if (ret)
+        goto fail;
+    ret = pthread_setname_np(sq->tid, "klippy_cserial");
     if (ret)
         goto fail;
 

klippy/klippy.py

@@ -404,4 +404,7 @@ def main():
         sys.exit(-1)
 
 if __name__ == '__main__':
+    import namedthreads
+    namedthreads.patch()
+    namedthreads.set_thread_name("klippy_main")
     main()

klippy/namedthreads.py

@@ -0,0 +1,73 @@
+import ctypes
+import ctypes.util
+import threading
+import logging
+
+# this is mostly copied from https://github.com/beniwohli/namedthreads/blob/master/namedthreads.py
+# itself copied from https://bugs.python.org/issue15500#msg230736
+
+
+def make_pthread_setname_np():
+    libpthread_path = ctypes.util.find_library("pthread")
+
+    if not libpthread_path:
+        # pthread library not found, not patching"
+        return
+
+    libpthread = ctypes.CDLL(libpthread_path)
+
+    if not hasattr(libpthread, "pthread_setname_np"):
+        # pthread library does not have pthread_setname_np function, not patching
+        return
+
+    pthread_setname_np = libpthread.pthread_setname_np
+    pthread_setname_np.argtypes = [ctypes.c_void_p, ctypes.c_char_p]
+    pthread_setname_np.restype = ctypes.c_int
+    return pthread_setname_np
+
+pthread_setname_np = make_pthread_setname_np()
+
+def set_thread_name(name, thread=None):
+    if hasattr(name, "encode"):
+        name = name.encode('ascii', 'replace')
+    if thread is None:
+        thread = threading.current_thread()
+    ident = getattr(thread, "ident", None)
+    ret = -1
+    if ident is not None:
+        ret = pthread_setname_np(ident, name[:15])
+    if ret != 0:
+        raise RuntimeError(f'Failed to set thread name {thread=} {ident=} {name=}')
+
+def patch():
+    if getattr(threading.Thread.start, "_namedthreads_patched", None):
+        # threading module is already patched
+        return
+
+    if pthread_setname_np is None:
+        logging.warn("Failed to get pthread_setname_np() wrapper")
+        return
+
+    orig_start = threading.Thread.start
+
+    def start(self):
+        orig_start(self)
+        try:
+            name = self.name
+            if name:
+                set_thread_name(name, self)
+        except Exception as e:
+            logging.warn("Failed to set thread name for %r: %s", self, e)
+
+    start._namedthreads_patched = True
+    start._namedthreads_orig = threading.Thread.start
+    threading.Thread.start = start
+    return True
+
+
+def unpatch():
+    if not getattr(threading.Thread.start, "_namedthreads_patched", None):
+        # threading module is not patched
+        return
+    patched_start = threading.Threading.start
+    threading.Thread.start = patched_start._namedthreads_orig

klippy/queuelogger.py

@@ -26,7 +26,7 @@ def __init__(self, filename):
         logging.handlers.TimedRotatingFileHandler.__init__(
             self, filename, when='midnight', backupCount=5)
         self.bg_queue = queue.Queue()
-        self.bg_thread = threading.Thread(target=self._bg_thread)
+        self.bg_thread = threading.Thread(target=self._bg_thread, name='klippy_logger')
         self.bg_thread.start()
         self.rollover_info = {}
     def _bg_thread(self):

klippy/serialhdl.py

@@ -82,7 +82,7 @@ def _start_session(self, serial_dev, serial_fd_type=b'u', client_id=0):
             self.ffi_lib.serialqueue_alloc(serial_dev.fileno(),
                                            serial_fd_type, client_id),
             self.ffi_lib.serialqueue_free)
-        self.background_thread = threading.Thread(target=self._bg_thread)
+        self.background_thread = threading.Thread(target=self._bg_thread, name='klippy_serial')
         self.background_thread.start()
         # Obtain and load the data dictionary from the firmware
         completion = self.reactor.register_callback(self._get_identify_data)