Use thread pool thumbnailer

lazy_player/__init__.py

@@ -29,7 +29,6 @@ def main():
     app = Application(thumbnailer=thumbnailer)
 
     try:
-        thumbnailer.start()
         app.run(None)
     finally:
-        thumbnailer.stop()
+        thumbnailer.shutdown()

lazy_player/thumbnailer.py

@@ -1,8 +1,8 @@
 from __future__ import annotations
 
+import multiprocessing
 import sys
-import threading
-from queue import Empty, Full, LifoQueue
+from concurrent.futures import ThreadPoolExecutor
 from typing import TYPE_CHECKING
 
 from gi.repository import GLib, Gst
@@ -22,15 +22,18 @@ DEFAULT_SEEK_FLAGS = (
 __all__ = ["Thumbnailer", "generate_thumbnail_sync"]
 
 
-class Thumbnailer(threading.Thread):
-    queue: LifoQueue[FileItem | None]
+MAX_WORKERS = max(1, multiprocessing.cpu_count() // 2)
 
+
+class Thumbnailer(ThreadPoolExecutor):
     def __init__(self):
-        super().__init__(daemon=True)
-        self.queue = LifoQueue(maxsize=20)
+        super().__init__(
+            thread_name_prefix="Thumbnailer",
+            max_workers=MAX_WORKERS,
+        )
 
     def generate_thumbnail(self, file_item: FileItem):
-        """Add a file item to the thumbnail queue"""
+        """Schedule thumbnail generation"""
 
         if not file_item.full_path.is_file():
             return
@@ -38,41 +41,19 @@ class Thumbnailer(threading.Thread):
         if file_item.attempted_thumbnail:
             return
 
-        try:
-            self.queue.put_nowait(file_item)
-        except Full:
-            pass
+        if self._work_queue.qsize() >= MAX_WORKERS:
+            # print("[thumbnail] Ignoring:", file_item.full_path.name)
+            return
 
+        self.submit(generate_thumbnail_sync, file_item)
         file_item.attempted_thumbnail = True
 
-    def stop(self):
-        """Stop the thumbnailer thread"""
-
-        try:
-            # Drop all pending items
-            while True:
-                self.queue.get_nowait()
-        except Empty:
-            pass
-
-        self.queue.put_nowait(None)
-        self.join()
-
-    def run(self) -> None:
-        """Process items from the queue continuously"""
-
-        while True:
-            file_item = self.queue.get(block=True)
-
-            if file_item is None:
-                break
-
-            generate_thumbnail_sync(file_item)
-
 
 def generate_thumbnail_sync(file_item: FileItem):
     """Generate thumbnail for a single file"""
 
+    # print("[thumbnailer] Generate:", file_item.full_path.name)
+
     pipeline_str = (
         "uridecodebin name=uridecodebin ! "
         "videoconvert ! "
@@ -95,13 +76,14 @@ def generate_thumbnail_sync(file_item: FileItem):
     try:
         # Set pipeline to PAUSED to get duration
         pipeline.set_state(Gst.State.PAUSED)
-        pipeline.get_state(Gst.SECOND)
+        pipeline.get_state(Gst.CLOCK_TIME_NONE)
 
-        # Seek to 1/3 of duration
+        # Obtain total duration
         success, duration = pipeline.query_duration(Gst.Format.TIME)
         if not success:
-            return
+            raise RuntimeError("Failed to query duration")
 
+        # Seek to 1/3 of duration
         seek_pos = duration // 3
         pipeline.seek_simple(Gst.Format.TIME, DEFAULT_SEEK_FLAGS, seek_pos)
 
@@ -110,16 +92,16 @@ def generate_thumbnail_sync(file_item: FileItem):
 
         sample = sink.emit("pull-sample")
         if not sample:
-            return
+            raise RuntimeError("Failed to pull sample")
 
         # Extract image data
         buffer = sample.get_buffer()
         if not buffer:
-            return
+            raise RuntimeError("Failed to get buffer")
 
         success, map_info = buffer.map(Gst.MapFlags.READ)
         if not success:
-            return
+            raise RuntimeError("Failed to map buffer")
 
         try:
             thumbnail = bytes(map_info.data)
@@ -133,7 +115,8 @@ def generate_thumbnail_sync(file_item: FileItem):
         GLib.idle_add(set_thumbnail)
 
     except Exception as err:
-        print("[thumbnailer] Error:", file_item.full_path, err, file=sys.stderr)
+        print("[thumbnailer] Error:", file_item.full_path.name, file=sys.stderr)
+        print("[thumbnailer]", err, file=sys.stderr)
 
     finally:
         pipeline.set_state(Gst.State.NULL)