[Ovmsdev] Duplicate timer callbacks (was: Branch for-v3.3 network issues)

Fri Jan 14 16:43:24 HKT 2022

The effect is also present with SPIRAM disabled (and 64K for 
cpuload_task to fit in internal RAM), and it's even more frequent when 
running in single core mode.

I haven't reviewed all our timers yet, I'll try to test periodic timers 
first for the effect so we know if these need to be reviewed also.

Regards,
Michael

Am 14.01.22 um 06:50 schrieb Mark Webb-Johnson:
> Good to hear this has been confirmed in a test case.
>
> Do we need to review all our use of timers? Or have you already checked?
>
> I wonder if it is reproducible single core and without SPI RAM? 
> Whether this is another ESP32 hardware bug affecting something else...
>
> Regards, Mark.
>
>> On 14 Jan 2022, at 12:03 AM, Michael Balzer <dexter at expeedo.de> wrote:
>>
>> Signed PGP part
>> Everyone,
>>
>> I've managed to reproduce the effect on a standard ESP32 development 
>> board with a simple test project only involving timers, some 
>> CPU/memory load & wifi networking.
>>
>> I've tested both the standard esp-idf release 3.3 and the latest 
>> esp-idf release 4.4 (using gcc 8.4) for this, and the effect is still 
>> present.
>>
>> → Bug report: https://github.com/espressif/esp-idf/issues/8234
>>
>> Attached are my test projects if you'd like to reproduce this or 
>> improve the test.
>>
>> I haven't tested periodic timer callbacks yet for the effect. These 
>> are normally designed to run periodically, but if the timing is 
>> important (e.g. on some CAN transmission?), this could cause 
>> erroneous behaviour as well.
>>
>> Regards,
>> Michael
>>
>>
>> Am 30.12.21 um 19:25 schrieb Michael Balzer:
>>> Followup to…
>>>
>>> Am 26.09.21 um 19:28 schrieb Michael Balzer:
>>>> If so, my conclusions so far would be:
>>>>
>>>> a) we've got a real heap corruption issue that sometimes gets 
>>>> triggered by the test. I've had it twice around the same place, 
>>>> i.e. within the scheduled event processing. I'll check my code.
>>>>
>>>> Am 26.09.21 um 18:46 schrieb Craig Leres:
>>>>> Second crash on the production module, CORRUPT HEAP after ~350 
>>>>> minutes.
>>>>>
>>>>> OVMS# CORRUPT HEAP: Bad head at 0x3f8adc78. Expected 0xabba1234 
>>>>> got 0x3f8adcc0
>>>>> abort() was called at PC 0x400844c3 on core 0
>>>
>>> I've found the heap corruption source and a new bug class:
>>>
>>> The corruption was caused by a duplicate free() (here via delete), 
>>> which was basically impossible: it was the free() call for the event 
>>> message for a delayed event delivery. There is exactly one producer 
>>> (OvmsEvents::ScheduleEvent) and exactly one consumer 
>>> (OvmsEvents::SignalScheduledEvent), which is called exactly once -- 
>>> when the single shot timer expires.
>>>
>>> In theory. _In reality, the timer callback occasionally gets 
>>> executed twice_. To exclude every possible race condition, I 
>>> enclosed both producer & consumer into a semaphore lock. I then 
>>> changed the code in order to clear the timer payload as soon as it's 
>>> read, and added a test for a NULL payload -- and voila, the timer 
>>> callback now gets occasionally called with a NULL payload, which is 
>>> also impossible as the allocation result is checked in the producer.
>>>
>>> I've had no luck reproducing this in a reduced test project, even 
>>> with multiple auto reload timers and distribution over both cores, 
>>> but I still see no other explanation than a bug in the FreeRTOS 
>>> timer service (or the Espressif FreeRTOS multi core adaption). Ah, 
>>> and yes, this occurs on the ESP32/r3 as well.
>>>
>>> You should be able to reproduce the effect using the same event test 
>>> loop as for the Duktape TypeError issue: 
>>> https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/474#issuecomment-1002687055
>>>
>>> My workaround prevents crashes and outputs a log entry when the NULL 
>>> payload is detected.
>>>
>>> Example log excerpt:
>>>
>>> script eval 'testcnt=0; PubSub.subscribe("usr.testev", function(ev) 
>>> { var ms=Number(ev.substr(11))||10; if (++testcnt % (3*1000/ms) == 
>>> 0) print(ev + ": " + testcnt); OvmsEvents.Raise("usr.testev."+ms, 
>>> ms); })'
>>> script eval 'testcnt=0; OvmsEvents.Raise("usr.testev.10")'
>>> I (13493019) events: ScheduleEvent: creating new timer
>>> *W (13495919) events: SignalScheduledEvent: duplicate callback 
>>> invocation detected*
>>> I (13497029) ovms-duk-util: [eval:1:] usr.testev.10: 300
>>> I (13501109) housekeeping: 2021-12-30 18:12:35 CET (RAM: 
>>> 8b=64448-67004 32b=6472)
>>> --
>>> I (13521779) ovms-duk-util: [eval:1:] usr.testev.10: 2100
>>> I (13525809) ovms-duk-util: [eval:1:] usr.testev.10: 2400
>>> *W (13527579) events: SignalScheduledEvent: duplicate callback 
>>> invocation detected**
>>> **W (13527629) events: SignalScheduledEvent: duplicate callback 
>>> invocation detected*
>>> I (13529839) ovms-duk-util: [eval:1:] usr.testev.10: 2700
>>> I (13533329) ovms-server-v2: Incoming Msg: MP-0 AFA
>>> --
>>> I (13579149) ovms-duk-util: [eval:1:] usr.testev.10: 6300
>>> I (13583319) ovms-duk-util: [eval:1:] usr.testev.10: 6600
>>> *W (13584679) events: SignalScheduledEvent: duplicate callback 
>>> invocation detected*
>>> I (13587439) ovms-duk-util: [eval:1:] usr.testev.10: 6900
>>> I (13591589) ovms-duk-util: [eval:1:] usr.testev.10: 7200
>>> --
>>> I (13714299) ovms-duk-util: [eval:1:] usr.testev.10: 16200
>>> I (13718339) ovms-duk-util: [eval:1:] usr.testev.10: 16500
>>> *W (13718719) events: SignalScheduledEvent: duplicate callback 
>>> invocation detected*
>>> I (13722459) ovms-duk-util: [eval:1:] usr.testev.10: 16800
>>> I (13726509) ovms-duk-util: [eval:1:] usr.testev.10: 17100
>>> --
>>> I (13743149) ovms-duk-util: [eval:1:] usr.testev.10: 18300
>>> I (13747129) ovms-duk-util: [eval:1:] usr.testev.10: 18600
>>> *W (13748979) events: SignalScheduledEvent: duplicate callback 
>>> invocation detected*
>>> I (13751299) ovms-duk-util: [eval:1:] usr.testev.10: 18900
>>> I (13755349) ovms-duk-util: [eval:1:] usr.testev.10: 19200
>>> --
>>> I (13784029) ovms-duk-util: [eval:1:] usr.testev.10: 21300
>>> I (13788059) ovms-duk-util: [eval:1:] usr.testev.10: 21600
>>> *W (13791409) events: SignalScheduledEvent: duplicate callback 
>>> invocation detected*
>>> I (13792179) ovms-duk-util: [eval:1:] usr.testev.10: 21900
>>> I (13796239) ovms-duk-util: [eval:1:] usr.testev.10: 22200
>>> …
>>>
>>>
>>> The bug frequency differs from boot to boot, but as you can see can 
>>> be very high. I've had runs with ~ 1 occurrence every 300.000 
>>> callbacks, and runs like the above with ~ 1 every 3.000 callbacks.
>>>
>>> If this is a common effect with timer callbacks, that may cause some 
>>> of the remaining issues. It's possible this only happens with single 
>>> shot timers, haven't checked our periodic timers yet.
>>>
>>> Any additional input on this is welcome.
>>>
>>> Regards,
>>> Michael
>>>
>>> -- 
>>> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
>>> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
>>>
>>> _______________________________________________
>>> OvmsDev mailing list
>>> OvmsDev at lists.openvehicles.com
>>> http://lists.openvehicles.com/mailman/listinfo/ovmsdev
>>
>> -- 
>> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
>> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
>> <test-timer-dupecall.zip>
>>
>
>
> _______________________________________________
> OvmsDev mailing list
> OvmsDev at lists.openvehicles.com
> http://lists.openvehicles.com/mailman/listinfo/ovmsdev

-- 
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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