apt-cache policy python3.13
python3.13:
Installed: 3.13.5-2+deb13u3
Candidate: 3.13.5-2+deb13u3
Version table:
*** 3.13.5-2+deb13u3 500
500 http://deb.debian.org/debian trixie/main amd64 Packages
100 /var/lib/dpkg/status
Looks like I cannot downgrade...I will just have to now restart the weewx.
I do have weewx set up in monit and if it does crash in theory it should
restart again.
On Wednesday, 15 July 2026 at 23:05:03 UTC+10 John Kline wrote:
> I believe the maintainers have what they need to push a fix. I’m hoping
> that will happen in a week or two.
>
> >> At least if it doesn't start I will know what to do
>
> It will start just fine. The issue is, each time weewx requests garbage
> collection (which, by default, weewx does every 3 hours), there is a small
> chance of a segment violation soon after. As such, the symptom will be
> that weewx stops running for no obvious reason (and nothing in the log
> after a garbage collection message).
>
> It is hard to say how often this might happen for a single instance of
> weewx running. The frequency may depend on what extensions you are running
> (and how many of them). It is conceivable that some won’t see the issue at
> all before the fix arrives.
>
> I was seeing the issue too often (as I run quite a few weewx instances);
> so I resorted to downgrading the python packages and put them on hold
> while waiting for the update.
>
> John
>
> On Jul 15, 2026, at 2:53 AM, Greg from Oz <[email protected]> wrote:
>
>
>
> So when does the new fix arrive?
> I upgraded the python 2 days ago and weewx has been running for 4
> days....I better not restart weewx.
> At least if it doesn't start I will know what to do...Thanks for the heads
> up.
>
> On Tuesday, 14 July 2026 at 08:17:42 UTC+10 Tom Keffer wrote:
>
>> Thanks, John, for your detailed report.
>>
>> On Mon, Jul 13, 2026 at 8:09 AM 'John Kline' via weewx-user <
>> [email protected]> wrote:
>>
>>> If you run WeeWX on Debian 13 (trixie) and your system installed the
>>> python3.13 update from the 13.6 point release (version 3.13.5-2+deb13u3,
>>> rolling out via unattended-upgrades since July 11), be aware that it can
>>> crash weewxd with a segmentation fault.
>>>
>>> What it looks like
>>> ------------------
>>> weewxd dies with SIGSEGV -- no Python traceback in the log, the process
>>> just exits. systemd shows "Main process exited, code=dumped,
>>> status=11/SEGV". If you look closely at the timing, the crash comes
>>> milliseconds after WeeWX's periodic garbage collection pass (the
>>> "Garbage collected N objects" INFO line, every 3 hours by default).
>>> weewxd is unusually good at tripping this bug precisely because it calls
>>> gc.collect() on that schedule while its other threads keep working.
>>>
>>> I run seven WeeWX machines (Raspberry Pi 5, all on trixie). Four crashes
>>> in the ~48 hours after the update reached them; the crash takes down
>>> maybe
>>> 1 in 25 GC passes, so it looks random and can hit anywhere from hours to
>>> days after a restart. The crashing thread differs every time (sqlite
>>> reads, report generation, image generation), so don't chase whatever
>>> happens to be in your traceback if you have faulthandler enabled -- it's
>>> the victim, not the cause.
>>>
>>> The cause
>>> ---------
>>> It is not WeeWX and not any extension. Debian's deb13u3 update
>>> backported
>>> a garbage-collector fix into Python 3.13.5 but omitted a second upstream
>>> commit that the fix depends on, so a GC pass can free memory that is
>>> still
>>> in use. It's tracked as Debian bug #1141977, the missing commit has been
>>> identified by bisection, and the maintainer is engaged, so I'd expect a
>>> fixed package (deb13u4) reasonably soon:
>>>
>>> https://bugs.debian.org/1141977
>>>
>>> Am I affected?
>>> --------------
>>> dpkg -l python3.13 | grep deb13u3
>>>
>>> Two things must both be true: the deb13u3 package is installed AND weewxd
>>> was (re)started after it was installed. A weewxd that has been running
>>> since before the upgrade still uses the old library and is safe until its
>>> next restart.
>>>
>>> What to do
>>> ----------
>>> 1. If your weewxd predates the upgrade, simply don't restart it until the
>>> fixed package arrives.
>>> 2. Otherwise, make crashes self-healing while you wait. A systemd
>>> drop-in (systemctl edit weewx) with:
>>>
>>> [Service]
>>> Restart=on-failure
>>> RestartSec=10
>>>
>>> turns each crash into ~15 seconds of downtime. I also recommend
>>> Environment=PYTHONFAULTHANDLER=1 there -- it logs a full thread dump
>>> on any future native crash, which is invaluable for problems like
>>> this one.
>>> 3. Raising gc_interval in weewx.conf reduces exposure but does not
>>> eliminate it (Python's automatic collections use the same broken
>>> code path), so I wouldn't rely on it.
>>> 4. When the fixed python3.13 package arrives, remember that a running
>>> weewxd keeps the old library until it is restarted -- do a
>>> "systemctl restart weewx" after the upgrade to actually get off the
>>> broken version.
>>>
>>> Downgrading to deb13u2 also works but re-opens the security fixes that
>>> update carried; with the auto-restart in place I don't think it's worth
>>> it.
>>>
>>> John
>>>
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>>>
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>>> .
>>>
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