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