Hacktoberfest 2026: los issues que los mantenedores marcaron para octubre, abiertos y aptos para principiantes. Explorar issues de Hacktoberfest

[BUG] pyservicemaker: Pipeline.stop() keeps the GIL and deadlocks against a Python probe

Abierto Apto para principiantes
  • ¿Algo no está bien?
#99 3 comentarios 0 reacciones 1 asignado Ver en GitHub

Los mantenedores suelen responder en 1 día

@nvqiezi ya está trabajando en esto.

Desde el 27/10/2026.

Evaluación

Dificultad
2/5
Tiempo estimado
1-3 horas
Aptitud para principiantes
78/100
Tipo de issue
Error
Claridad
Bien especificado
Estado de actividad
Activo
Stack tecnológico
cpp, docker, linux, python
Área
api, backend

Línea de trabajo

Lee src/service-maker/sources/python/src/bindings/pipeline.h alrededor del enlace de Pipeline.stop() y compáralo con los enlaces adyacentes que liberan el GIL. El issue incluye un script de reproducción en Python y un comando de Docker para reproducir el deadlock con una sonda. Actualiza el enlace para que stop() libere el GIL mientras se ejecuta y luego confirma que el caso de la sonda se completa sin quedarse bloqueado.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

bug

Describe the bug

Pipeline.stop() in pyservicemaker keeps the GIL while it sends EOS into the pipeline. If a streaming thread is inside a Python probe (BufferOperator, BatchMetadataOperator) at that moment, the two threads deadlock: stop() waits for a lock that the streaming thread holds, and the streaming thread waits for the GIL. Every Python thread then freezes, so a Python timeout or watchdog thread cannot help either.

The binding is in src/service-maker/sources/python/src/bindings/pipeline.h: .def("stop", &Pipeline::stop, ...) has no py::gil_scoped_release, while wait, seek, start_recording and stop_recording next to it do. Pipeline::stop() calls gst_element_send_event(pipeline, gst_event_new_eos()), which blocks while the source's streaming thread is in gst_pad_push.

Steps/Code to reproduce bug

Save as repro.py:

import faulthandler
import sys
import threading
import time

from pyservicemaker import BufferOperator, Pipeline, Probe


class Count(BufferOperator):
    def __init__(self):
        super().__init__()
        self.buffers = 0

    def handle_buffer(self, buffer):
        self.buffers += 1
        return True


runs = int(sys.argv[1])
with_probe = sys.argv[2] == "probe"
for run in range(1, runs + 1):
    count = Count()
    pipeline = Pipeline(f"stop-{run}")
    # An unpaced source, so the streaming thread calls the probe all the time.
    pipeline.add("videotestsrc", "src", {"pattern": 2})
    pipeline.add("fakesink", "sink", {"sync": False})
    pipeline.link("src", "sink")
    if with_probe:
        pipeline.attach("src", Probe("count", count))
    waiter = threading.Thread(target=pipeline.wait)
    pipeline.start()
    time.sleep(0.5)
    # Prints every thread's stack and exits if stop() and wait() do not finish in 10 s.
    faulthandler.dump_traceback_later(10, exit=True)
    started = time.monotonic()
    waiter.start()
    pipeline.stop()
    waiter.join()
    faulthandler.cancel_dump_traceback_later()
    print(f"run {run}: stopped in {time.monotonic() - started:.2f} s after {count.buffers} buffers", flush=True)
print("all runs stopped")

Run it in the stock container (pyyaml is installed first because import pyservicemaker needs it, see #98):

docker run --rm --gpus all -v "$PWD":/repro --entrypoint bash nvcr.io/nvidia/deepstream:9.1-triton-multiarch \
  -c "pip install -q --break-system-packages pyyaml && python3 /repro/repro.py 10 probe"

With no-probe in place of probe, all 10 runs stop at once. With the probe, stop() deadlocks within the first two runs (on run 1 or run 2 in three attempts):

Posted EOS to stop pipeline
run 1: stopped in 0.00 s after 5407 buffers
Timeout (0:00:10)!
  File "/usr/local/lib/python3.12/dist-packages/pyservicemaker/pipeline.py", line 201 in wait
  File "/usr/local/lib/python3.12/dist-packages/pyservicemaker/pipeline.py", line 214 in stop
  File "/repro/repro.py", line 38 in <module>

Native stacks of the deadlocked process (gdb -p <pid> -batch -ex "thread apply all bt", run with --cap-add SYS_PTRACE), trimmed to the frames that matter. The main thread holds the GIL and waits for the stream lock:

#1  pthread_mutex_lock () at libc.so.6
#3  gst_element_send_event () at libgstreamer-1.0.so.0
#6  deepstream::Pipeline::stop() () at libnvds_service_maker.so
#7  pybind11::cpp_function::cpp_function<deepstream::Pipeline&, PipelineWrapper, ...>::{lambda(PipelineWrapper*)#1}::operator() at _pydeepstream.so

The source's streaming thread holds the stream lock and waits for the GIL:

Thread 4 (LWP 101) "src:src"
#1  pthread_cond_timedwait () at libc.so.6
#3  PyEval_AcquireThread ()
#4  pybind11::gil_scoped_acquire::gil_scoped_acquire() () at _pydeepstream.so
#5  PyBufferOperator::handle_buffer(deepstream::Buffer) () at _pydeepstream.so
#6  BufferOperator_::handleBuffer(deepstream::BufferProbe&, deepstream::Buffer&) () at _pydeepstream.so
#7  deepstream::genric_probe_callback(_GstPad*, _GstPadProbeInfo*, void*) () at libnvds_service_maker.so
#12 gst_pad_push () at libgstreamer-1.0.so.0

Expected behavior

stop() releases the GIL while it runs, as wait() does, so a probe can finish and stop() returns:

.def("stop", [](PipelineWrapper& self) {
    py::gil_scoped_release release;
    self.stop();
}, pydeepstreamdoc::pipeline::PipelineDoc::stop)

(Pipeline.stop in pipeline.py already returns self, so the binding does not need to return the pipeline.)

Environment details

  • Environment location: Docker on bare-metal (Ubuntu 26.04.1 LTS host, RTX A4000 Laptop GPU, driver 595.99.02)
  • Method of DeepStream install: Docker, nvcr.io/nvidia/deepstream:9.1-triton-multiarch (digest sha256:fd31f5b44ababdbdee8cd397a375e888191b49e402ac237254a4cdc239130f5b), DeepStream 9.1.0, pyservicemaker 0.0.1, TensorRT 10.16.0.72, CUDA 13.2
  • Docker command: see the steps above
  • scripts/print_env.sh output, run inside the same container:
Click here to see environment details
 **git***
 Not inside a git repository
 
 ***OS Information***
 DISTRIB_ID=Ubuntu
 DISTRIB_RELEASE=24.04
 DISTRIB_CODENAME=noble
 DISTRIB_DESCRIPTION="Ubuntu 24.04.4 LTS"
 PRETTY_NAME="Ubuntu 24.04.4 LTS"
 NAME="Ubuntu"
 VERSION_ID="24.04"
 VERSION="24.04.4 LTS (Noble Numbat)"
 VERSION_CODENAME=noble
 ID=ubuntu
 ID_LIKE=debian
 HOME_URL="https://www.ubuntu.com/"
 SUPPORT_URL="https://help.ubuntu.com/"
 BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
 PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
 UBUNTU_CODENAME=noble
 LOGO=ubuntu-logo
 Linux b5ade298bb5a 7.0.0-38-generic #38-Ubuntu SMP PREEMPT_DYNAMIC Fri Sep  4 09:10:14 UTC 2026 x86_64 x86_64 x86_64 GNU/Linux
 
 ***GPU Information***
 Thu Oct 22 14:52:51 2026
 +-----------------------------------------------------------------------------------------+
 | NVIDIA-SMI 595.99.02              Driver Version: 595.99.02      CUDA Version: 13.2     |
 +-----------------------------------------+------------------------+----------------------+
 | GPU  Name                 Persistence-M | Bus-Id          Disp.A | Volatile Uncorr. ECC |
 | Fan  Temp   Perf          Pwr:Usage/Cap |           Memory-Usage | GPU-Util  Compute M. |
 |                                         |                        |               MIG M. |
 |=========================================+========================+======================|
 |   0  NVIDIA RTX A4000 Laptop GPU    Off |   00000000:01:00.0 Off |                  N/A |
 | N/A   63C    P0             25W /   80W |     161MiB /   8192MiB |      0%      Default |
 |                                         |                        |                  N/A |
 +-----------------------------------------+------------------------+----------------------+
 
 +-----------------------------------------------------------------------------------------+
 | Processes:                                                                              |
 |  GPU   GI   CI              PID   Type   Process name                        GPU Memory |
 |        ID   ID                                                               Usage      |
 |=========================================================================================|
 |  No running processes found                                                             |
 +-----------------------------------------------------------------------------------------+
 
 ***CPU***
 Architecture:                            x86_64
 CPU op-mode(s):                          32-bit, 64-bit
 Address sizes:                           39 bits physical, 48 bits virtual
 Byte Order:                              Little Endian
 CPU(s):                                  16
 On-line CPU(s) list:                     0-15
 Vendor ID:                               GenuineIntel
 Model name:                              11th Gen Intel(R) Core(TM) i9-11950H @ 2.60GHz
 CPU family:                              6
 Model:                                   141
 Thread(s) per core:                      2
 Core(s) per socket:                      8
 Socket(s):                               1
 Stepping:                                1
 CPU(s) scaling MHz:                      42%
 CPU max MHz:                             5000.0000
 CPU min MHz:                             800.0000
 BogoMIPS:                                5222.40
 Flags:                                   fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l2 cdp_l2 ssbd ibrs ibpb stibp ibrs_enhanced tpr_shadow flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid rdt_a avx512f avx512dq rdseed adx smap avx512ifma clflushopt clwb intel_pt avx512cd sha_ni avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves split_lock_detect user_shstk dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_epp hwp_pkg_req vnmi avx512vbmi umip pku ospke avx512_vbmi2 gfni vaes vpclmulqdq avx512_vnni avx512_bitalg avx512_vpopcntdq rdpid movdiri movdir64b fsrm avx512_vp2intersect md_clear ibt flush_l1d arch_capabilities
 Virtualization:                          VT-x
 L1d cache:                               384 KiB (8 instances)
 L1i cache:                               256 KiB (8 instances)
 L2 cache:                                10 MiB (8 instances)
 L3 cache:                                24 MiB (1 instance)
 NUMA node(s):                            1
 NUMA node0 CPU(s):                       0-15
 Vulnerability Gather data sampling:      Vulnerable
 Vulnerability Ghostwrite:                Not affected
 Vulnerability Indirect target selection: Mitigation; Aligned branch/return thunks
 Vulnerability Itlb multihit:             Not affected
 Vulnerability L1tf:                      Not affected
 Vulnerability Mds:                       Not affected
 Vulnerability Meltdown:                  Not affected
 Vulnerability Mmio stale data:           Not affected
 Vulnerability Old microcode:             Not affected
 Vulnerability Reg file data sampling:    Not affected
 Vulnerability Retbleed:                  Not affected
 Vulnerability Spec rstack overflow:      Not affected
 Vulnerability Spec store bypass:         Mitigation; Speculative Store Bypass disabled via prctl
 Vulnerability Spectre v1:                Mitigation; usercopy/swapgs barriers and __user pointer sanitization
 Vulnerability Spectre v2:                Mitigation; Enhanced / Automatic IBRS; IBPB conditional; PBRSB-eIBRS SW sequence; BHI SW loop, KVM SW loop
 Vulnerability Srbds:                     Not affected
 Vulnerability Tsa:                       Not affected
 Vulnerability Tsx async abort:           Not affected
 Vulnerability Vmscape:                   Not affected
 
 ***CMake***
 /usr/bin/cmake
 cmake version 3.28.3
 
 CMake suite maintained and supported by Kitware (kitware.com/cmake).
 
 ***g++***
 /usr/bin/g++
 g++ (Ubuntu 13.3.0-6ubuntu2~24.04.1) 13.3.0
 Copyright (C) 2023 Free Software Foundation, Inc.
 This is free software; see the source for copying conditions.  There is NO
 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 
 
 ***nvcc***
 /usr/local/cuda/bin/nvcc
 nvcc: NVIDIA (R) Cuda compiler driver
 Copyright (c) 2005-2026 NVIDIA Corporation
 Built on Mon_Mar_02_09:52:23_PM_PST_2026
 Cuda compilation tools, release 13.2, V13.2.51
 Build cuda_13.2.r13.2/compiler.37434383_0
 
 ***Python***
 
 ***Environment Variables***
 PATH                            : /opt/proto/bin:/opt/tritonserver/bin:/usr/local/nvidia/bin:/usr/local/cuda/bin:/usr/local/mpi/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/ucx/bin:/opt/amazon/efa/bin:/.local/bin
 LD_LIBRARY_PATH                 : /opt/tritonserver/lib:/opt/tritonclient/lib:/usr/src/tensorrt/lib:/opt/riva/lib:/usr/local/cuda-13/lib64:/usr/lib/x86_64-linux-gnu:/opt/hpcx/ucc/lib/:/opt/hpcx/ucx/lib/:/usr/local/cuda/compat/lib:/usr/local/nvidia/lib:/usr/local/nvidia/lib64:/.local/lib
 NUMBAPRO_NVVM                   :
 NUMBAPRO_LIBDEVICE              :
 CONDA_PREFIX                    :
 PYTHON_PATH                     :
 
 conda not found
 ***pip packages***
 /usr/bin/pip
 Package             Version
 ------------------- ---------------
 annotated-doc       0.0.4
 annotated-types     0.7.0
 anyio               4.12.1
 apparmor            4.0.1
 certifi             2026.2.25
 cupy-cuda13x        13.6.0
 distlib             0.4.0
 distro              1.9.0
 fastapi             0.138.1
 fastrlock           0.8.3
 filelock            3.25.2
 h11                 0.16.0
 httpcore            1.0.9
 httpx               0.27.2
 idna                3.11
 iniconfig           2.3.0
 jaraco.context      6.1.0
 jiter               0.13.0
 LibAppArmor         4.0.1
 numpy               1.26.4
 openai              1.107.3
 packaging           24.0
 partial-json-parser 0.2.1.1.post7
 pip                 24.0
 platformdirs        4.9.4
 pluggy              1.6.0
 pydantic            2.10.6
 pydantic_core       2.27.2
 Pygments            2.19.2
 pyservicemaker      0.0.1
 pytest              9.0.2
 python-apt          2.7.7+ubuntu5.2
 python-discovery    1.1.3
 scipy               1.16.3
 setuptools          78.1.1
 sniffio             1.3.1
 starlette           0.52.1
 tqdm                4.67.3
 tritonfrontend      2.67.0
 tritonserver        0.0.0
 typing_extensions   4.15.0
 typing-inspection   0.4.2
 virtualenv          21.2.0
 wheel               0.42.0

Additional context

Any Python application that stops a pipeline with probes attached can hit this; the faster the source, the more likely. A service that stops on SIGTERM (for example in Kubernetes) then hangs until it is killed, and its sinks are not finalized. Calling stop() from another Python thread does not help, because the held GIL freezes every Python thread. The only workaround we found is a watchdog that runs outside Python, such as faulthandler.dump_traceback_later(timeout, exit=True), which kills the process.

Lenguaje dominante
C++
Estrellas
283
Forks
62
Merge medio
2 h 24 min
PR fusionados (30 d)
20

Preparar el entorno

Este proyecto no incluye contenedor de desarrollo, Dockerfile ni guía de contribución, así que la configuración corre por tu cuenta: empieza por su README y consulta nuestra guía para la primera contribución para los pasos generales.

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

Más de NVIDIA/DeepStream

Todos los issues de NVIDIA/DeepStream

Issues similares

Más issues de C++

Recibe los nuevos issues en tu correo

Un resumen breve de issues de GitHub para principiantes.