blakeblackshear.frigate/frigate/camera/__init__.py
Nicolas Mowen 8485023442
Use Fork-Server As Spawn Method (#18682)
* Set runtime

* Use count correctly

* Don't assume camera sizes

* Use separate zmq proxy for object detection

* Correct order

* Use forkserver

* Only store PID instead of entire process reference

* Cleanup

* Catch correct errors

* Fix typing

* Remove before_run from process util

The before_run never actually ran because:

You're right to suspect an issue with before_run not being called and a potential deadlock. The way you've implemented the run_wrapper using __getattribute__ for the run method of BaseProcess is a common pitfall in Python's multiprocessing, especially when combined with how multiprocessing.Process works internally.

Here's a breakdown of why before_run isn't being called and why you might be experiencing a deadlock:

The Problem: __getattribute__ and Process Serialization
When you create a multiprocessing.Process object and call start(), the multiprocessing module needs to serialize the process object (or at least enough of it to re-create the process in the new interpreter). It then pickles this serialized object and sends it to the newly spawned process.

The issue with your __getattribute__ implementation for run is that:

run is retrieved during serialization: When multiprocessing tries to pickle your Process object to send to the new process, it will likely access the run attribute. This triggers your __getattribute__ wrapper, which then tries to bind run_wrapper to self.
run_wrapper is bound to the parent process's self: The run_wrapper closure, when created in the parent process, captures the self (the Process instance) from the parent's memory space.
Deserialization creates a new object: In the child process, a new Process object is created by deserializing the pickled data. However, the run_wrapper method that was pickled still holds a reference to the self from the parent process. This is a subtle but critical distinction.
The child's run is not your wrapped run: When the child process starts, it internally calls its own run method. Because of the serialization and deserialization process, the run method that's ultimately executed in the child process is the original multiprocessing.Process.run or the Process.run if you had directly overridden it. Your __getattribute__ magic, which wraps run, isn't correctly applied to the Process object within the child's context.

* Cleanup

* Logging bugfix (#18465)

* use mp Manager to handle logging queues

A Python bug (https://github.com/python/cpython/issues/91555) was preventing logs from the embeddings maintainer process from printing. The bug is fixed in Python 3.14, but a viable workaround is to use the multiprocessing Manager, which better manages mp queues and causes the logging to work correctly.

* consolidate

* fix typing

* Fix typing

* Use global log queue

* Move to using process for logging

* Convert camera tracking to process

* Add more processes

* Finalize process

* Cleanup

* Cleanup typing

* Formatting

* Remove daemon

---------

Co-authored-by: Josh Hawkins <32435876+hawkeye217@users.noreply.github.com>
2025-06-12 12:12:34 -06:00

69 lines
2.0 KiB
Python

import multiprocessing as mp
from multiprocessing.managers import SyncManager
from multiprocessing.sharedctypes import Synchronized
from multiprocessing.synchronize import Event
class CameraMetrics:
camera_fps: Synchronized
detection_fps: Synchronized
detection_frame: Synchronized
process_fps: Synchronized
skipped_fps: Synchronized
read_start: Synchronized
audio_rms: Synchronized
audio_dBFS: Synchronized
frame_queue: mp.Queue
process_pid: Synchronized
capture_process_pid: Synchronized
ffmpeg_pid: Synchronized
def __init__(self, manager: SyncManager):
self.camera_fps = manager.Value("d", 0)
self.detection_fps = manager.Value("d", 0)
self.detection_frame = manager.Value("d", 0)
self.process_fps = manager.Value("d", 0)
self.skipped_fps = manager.Value("d", 0)
self.read_start = manager.Value("d", 0)
self.audio_rms = manager.Value("d", 0)
self.audio_dBFS = manager.Value("d", 0)
self.frame_queue = manager.Queue(maxsize=2)
self.process_pid = manager.Value("i", 0)
self.capture_process_pid = manager.Value("i", 0)
self.ffmpeg_pid = manager.Value("i", 0)
class PTZMetrics:
autotracker_enabled: Synchronized
start_time: Synchronized
stop_time: Synchronized
frame_time: Synchronized
zoom_level: Synchronized
max_zoom: Synchronized
min_zoom: Synchronized
tracking_active: Event
motor_stopped: Event
reset: Event
def __init__(self, *, autotracker_enabled: bool):
self.autotracker_enabled = mp.Value("i", autotracker_enabled)
self.start_time = mp.Value("d", 0)
self.stop_time = mp.Value("d", 0)
self.frame_time = mp.Value("d", 0)
self.zoom_level = mp.Value("d", 0)
self.max_zoom = mp.Value("d", 0)
self.min_zoom = mp.Value("d", 0)
self.tracking_active = mp.Event()
self.motor_stopped = mp.Event()
self.reset = mp.Event()
self.motor_stopped.set()