smaple grabmultiplecameras gives segfault when using more than one camera

[tale-aasland]

Describe what you want to implement and what the issue & the steps to reproduce it are:

Hi,

I'm new to pypylon, and presently I'm simply testing the samples. The goal is to use multiple cameras, so I ran the sample snippet grabmultiplecameras.py. It runs nicely with only one camera. However, if I use two or more cameras, the script runs through everything as it should, gives the output and then segfaults at the end.

Final terminal output:
Camera 0 : acA800-510uc
GrabSucceeded: True
SizeX: 816
SizeY: 616
Gray value of first pixel: 19
Segmentation fault (core dumped)

Does anyone know what's happening?

Thanks!

Is your camera operational in Basler pylon viewer on your platform

Yes

Hardware setup used

System:
Kernel: 6.8.0-85-generic arch: x86_64 bits: 64 compiler: gcc v: 13.3.0
Desktop: Cinnamon v: 6.4.8 Distro: Linux Mint 22.2 Zara
base: Ubuntu 24.04 noble
Machine:
Type: Desktop System: HP product: HP EliteDesk 800 G8 Tower PC v: SBKPF
serial:
Mobo: HP model: 889C v: KBC Version 10.04.23 serial:
UEFI: HP v: T01 Ver. 02.19.00 date: 07/04/2025
CPU:
Info: 8-core model: 11th Gen Intel Core i7-11700 bits: 64 type: MT MCP
arch: Rocket Lake rev: 1 cache: L1: 640 KiB L2: 4 MiB L3: 16 MiB

RAM 32GB

Cameras are plugged directly into the usb 3 ports of my desktop PC.

Cables: Cable USB 3.0, Micro B sl/A, P, 5 m and 3m

Camera(s) used

Camera 1: acA1440-220uc, device version 107653-07, device firmware version 107653-07;U;acA1440_220uc;V1.4-4;1

Camera 2: acA800-510uc, device version 106765-04, device firmware version 106765-04;U;acA800-510u;V0.5-1;1

Runtime information:

pylon version is 8.10 (it's the newest one that I could get working on this distro).

python: 3.12.3 (main, Aug 14 2025, 17:47:21) [GCC 13.3.0]
platform: linux/x86_64/6.8.0-85-generic
pypylon: 4.2.0 / 10.2.1.471

[thiesmoeller]

Please report where the segfault happens.

This is a gdb oneliner for it

gdb --args python3 your_script.py -batch -ex run -ex bt -ex quit

[tale-aasland]

Thanks! So, using gdb run and then backtrace gives the following output:

(gdb) run
Starting program: /usr/bin/python3 grabmultiplecameras.py -batch -ex run -ex bt -ex quit
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffcffff6c0 (LWP 8869)]
[New Thread 0x7fffcf7fe6c0 (LWP 8870)]
[New Thread 0x7fffceffd6c0 (LWP 8871)]
[New Thread 0x7fffce7fc6c0 (LWP 8872)]
[New Thread 0x7fffcdffb6c0 (LWP 8873)]
[New Thread 0x7fffcd7fa6c0 (LWP 8874)]
[New Thread 0x7fffccff96c0 (LWP 8875)]
[New Thread 0x7fffcc7f86c0 (LWP 8876)]
[New Thread 0x7fffcbff76c0 (LWP 8877)]
[New Thread 0x7fffcb7f66c0 (LWP 8878)]
[New Thread 0x7fffcaff56c0 (LWP 8879)]
[New Thread 0x7fffca7f46c0 (LWP 8880)]
[New Thread 0x7fffc9ff36c0 (LWP 8881)]
[New Thread 0x7fffc97f26c0 (LWP 8882)]
[New Thread 0x7fffc8ff16c0 (LWP 8883)]
[New Thread 0x7fffc59ff6c0 (LWP 8884)]
[Thread 0x7fffc59ff6c0 (LWP 8884) exited]
[New Thread 0x7fffc4bff6c0 (LWP 8885)]
[New Thread 0x7fffc43fe6c0 (LWP 8886)]
[New Thread 0x7fffc35ff6c0 (LWP 8887)]
[New Thread 0x7fffc13ff6c0 (LWP 8888)]
Using device acA800-510uc
Using device acA800-510um
[New Thread 0x7fffc0bfe6c0 (LWP 8889)]
[New Thread 0x7fffbbfff6c0 (LWP 8890)]
[New Thread 0x7fffbb7fe6c0 (LWP 8891)]
Using device Emulation
[New Thread 0x7fffbaffd6c0 (LWP 8892)]
[New Thread 0x7fffba7fc6c0 (LWP 8893)]
[New Thread 0x7fffb9ffb6c0 (LWP 8894)]
[New Thread 0x7fffb97fa6c0 (LWP 8895)]
[New Thread 0x7fffb8ff96c0 (LWP 8896)]
[New Thread 0x7fff9ffff6c0 (LWP 8897)]
[New Thread 0x7fff9f7fe6c0 (LWP 8898)]
[New Thread 0x7fff9effd6c0 (LWP 8899)]
[New Thread 0x7fff9e7fc6c0 (LWP 8900)]
Camera 0 : acA800-510uc
GrabSucceeded: True
SizeX: 640
SizeY: 480
Gray value of first pixel: 26
Camera 0 : acA800-510uc
GrabSucceeded: True
SizeX: 640
SizeY: 480
Gray value of first pixel: 19
Camera 0 : acA800-510uc
GrabSucceeded: True
SizeX: 640
SizeY: 480
Gray value of first pixel: 12
Camera 0 : acA800-510uc
GrabSucceeded: True
SizeX: 640
SizeY: 480
Gray value of first pixel: 19
Camera 0 : acA800-510uc
GrabSucceeded: True
SizeX: 640
SizeY: 480
Gray value of first pixel: 6
Camera 1 : acA800-510um
GrabSucceeded: True
SizeX: 128
SizeY: 370
Gray value of first pixel: 4
Camera 0 : acA800-510uc
GrabSucceeded: True
SizeX: 640
SizeY: 480
Gray value of first pixel: 19
Camera 0 : acA800-510uc
GrabSucceeded: True
SizeX: 640
SizeY: 480
Gray value of first pixel: 26
Camera 0 : acA800-510uc
GrabSucceeded: True
SizeX: 640
SizeY: 480
Gray value of first pixel: 29
Camera 0 : acA800-510uc
GrabSucceeded: True
SizeX: 640
SizeY: 480
Gray value of first pixel: 6
[Thread 0x7fffb9ffb6c0 (LWP 8894) exited]
[Thread 0x7fffba7fc6c0 (LWP 8893) exited]
[Thread 0x7fff9ffff6c0 (LWP 8897) exited]
[Thread 0x7fffb8ff96c0 (LWP 8896) exited]
[Thread 0x7fff9e7fc6c0 (LWP 8900) exited]
[Thread 0x7fff9effd6c0 (LWP 8899) exited]
[Thread 0x7fffc0bfe6c0 (LWP 8889) exited]
[Thread 0x7fffbb7fe6c0 (LWP 8891) exited]
[Thread 0x7fffbbfff6c0 (LWP 8890) exited]
[Thread 0x7fff9f7fe6c0 (LWP 8898) exited]
[Thread 0x7fffb97fa6c0 (LWP 8895) exited]
[Thread 0x7fffbaffd6c0 (LWP 8892) exited]
[Thread 0x7fffc13ff6c0 (LWP 8888) exited]
[Thread 0x7fffc43fe6c0 (LWP 8886) exited]
[Thread 0x7fffc4bff6c0 (LWP 8885) exited]
[Thread 0x7fffc35ff6c0 (LWP 8887) exited]

Thread 1 "python3" received signal SIGSEGV, Segmentation fault.
0x00007fffc6087347 in ?? ()
(gdb) backtrace
#0 0x00007fffc6087347 in ?? ()
#1 0x00007fffc6436778 in ?? ()
#2 0x00007fffc608758f in ?? ()
#3 0x00007ffff7e04fa8 in __new_exitfn_called () from /lib/x86_64-linux-gnu/libc.so.6
#4 0x00007ffff7c47a76 in __run_exit_handlers (status=status@entry=0, listp=,
run_list_atexit=run_list_atexit@entry=true, run_dtors=run_dtors@entry=true) at ./stdlib/exit.c:108
#5 0x00007ffff7c47bbe in __GI_exit (status=status@entry=0) at ./stdlib/exit.c:138
#6 0x00000000006b12b2 in Py_Exit (sts=0) at ../Python/pylifecycle.c:3060
#7 0x00000000006b46ed in handle_system_exit () at ../Python/pythonrun.c:756
#8 0x00000000006b455c in _PyErr_PrintEx (tstate=0xba6ac8 <_PyRuntime+459656>, set_sys_last_vars=1) at ../Python/pythonrun.c:765
#9 0x00000000006b413b in PyErr_PrintEx (set_sys_last_vars=1) at ../Python/pythonrun.c:845
#10 PyErr_Print () at ../Python/pythonrun.c:851
#11 _PyRun_SimpleFileObject (fp=fp@entry=0xbe44a0,
filename=filename@entry='/home/tale/camera_test/pypylon_scripts/grabmultiplecameras.py', closeit=closeit@entry=1,
flags=flags@entry=0x7fffffffcfb8) at ../Python/pythonrun.c:439
#12 0x00000000006b3f2f in _PyRun_AnyFileObject (fp=0xbe44a0,
filename=filename@entry='/home/tale/camera_test/pypylon_scripts/grabmultiplecameras.py', closeit=closeit@entry=1,
flags=flags@entry=0x7fffffffcfb8) at ../Python/pythonrun.c:78
#13 0x00000000006bbf45 in pymain_run_file_obj (skip_source_first_line=0,
filename='/home/tale/camera_test/pypylon_scripts/grabmultiplecameras.py', program_name='/usr/bin/python3')
at ../Modules/main.c:360
#14 pymain_run_file (config=0xb496a8 <_PyRuntime+77672>) at ../Modules/main.c:379
#15 pymain_run_python (exitcode=0x7fffffffcfac) at ../Modules/main.c:629
#16 Py_RunMain () at ../Modules/main.c:709
#17 0x00000000006bba2d in Py_BytesMain (argc=, argv=) at ../Modules/main.c:763
#18 0x00007ffff7c2a1ca in __libc_start_call_main (main=main@entry=0x518bd0

, argc=argc@entry=9,
argv=argv@entry=0x7fffffffd1f8) at ../sysdeps/nptl/libc_start_call_main.h:58
#19 0x00007ffff7c2a28b in __libc_start_main_impl (main=0x518bd0 , argc=9, argv=0x7fffffffd1f8, init=,
fini=, rtld_fini=, stack_end=0x7fffffffd1e8) at ../csu/libc-start.c:360
#20 0x0000000000656a35 in _start ()

[tale-aasland]

Btw, this happens no matter what combinations of cameras I use, acA800-510uc, acA800-510um or acA1440-220uc.

[thiesmoeller]

Thanks for the back trace.

It is happening in the shutdown phase.
The normal operation works as expected.
We will take a look into it