Ludovic,

Am 31.10.22 um 10:59 schrieb Ludovic LANGE:

(I'm reposting because I had the impression that my message didn't get through. If it appears as a duplicate, please forgive me - and delete the double post if necessary. Still learning how to handle this delay between post and list visibility (moderation ?))

You're right, didn't get through, but there is no moderation. Checked your junk folder for an error message? Possibly Mark can see something in the logs.

Metrics are properly generated (from DBC), and properly displayed on the dashboard. However, the combination of the "intense" bus traffic, + number of generated metrics seems to be, in some way, overflowing the capacity of the WebSocketHandler, which results in a reboot from time to time:

W (5111095) websocket: WebSocketHandler[0x3f8d1654]: job queue overflow resolved, 14 drops
W (5111095) websocket: WebSocketHandler[0x3f8d1654]: job queue overflow detected
I (5111105) metrics: Modified metric v.g.current: 0A
I (5111105) metrics: Modified metric v.m.rpm: 763
I (5111115) metrics: Modified metric v.i.temp: 34.1°C
W (5111115) websocket: WebSocketHandler[0x3f8d1654]: job queue overflow detected
W (5111125) websocket: WebSocketHandler[0x3f8d1654]: job queue overflow detected

A WebSocket client channel can jam easily if it can't transmit the data to the client fast enough. This doesn't depend on the actual Wifi connection quality alone, but also on the processing speed of the client device. My impression is, complex and fast chart updates can cause the Javascript engine needing to do a lot of memory management work.

I haven't had the time to do an analysis on this, but I'm pretty sure there are options to reduce the load. The dashboard & chart data processing is still my first implementation, I didn't invest much time in optimization on that. For example, every new data series is a new allocation, so the garbage collector has quite some work to do.

Having said that, you should also try to reduce the data volume. From your logs it seems you've got metrics tracing enabled. That produces a log message on every metrics update, and all log messages are transmitted via the WebSocket channel.

E (5111845) task_wdt: Tasks currently running:
E (5111845) task_wdt: CPU 0: wifi
E (5111845) task_wdt: CPU 1: OVMS Console

If you didn't execute a command on the console at that moment, that's probably also an indicator for a high log load.

Please note that the Lab setup has:

OVMS connected to the Lab network

The computer (displaying the dashboard) also connected to the Lab network

(While, in the car, the computer / tablet would be directly connected to OVMS' wifi)

Shouldn't make much of a difference. But you could try configuring just Wifi client or ap mode, not both, depending on the setup. AP is running on the same channel, so might cut off some capacity.

That's it for the context, now a few questions:

As I don't know about the capabilities of the OVMS for CAN bus traffic analysis, does it looks like the number / frequency of messages I'm injecting is unreasonable ?

No.

It seems like there is a buffering / consolidation of the metrics before sending them to the web socket ; is this tweakable in some way ?

Metrics updates are initiated by the web client update ticket every 250 ms. You can experiment with changing the interval or make that a configuration if you like, but I had bad results with higher frequencies by producing too much load on the smartphones tested, and lower frequencies are bad for a smooth UI experience.

Regarding the queue overflow you might experiment with raising the queue size, which is currently 50 jobs. But if 50 tx jobs are reached, chances are you've got Wifi or client capacity issues.

Does the DBC processor add a significant processing time (compared to a dedicated vehicle module) when processing CAN data ?

Don't know, haven't used the DBC processor for real data.

What would be the best way to diagnose / confirm the health of the processes involved here ?

Use the task monitoring (module tasks) to check the CPU load of your processes.

Reduce any unnecessary load, for example avoid excessive logging, user event creation, file writes and especially SD card accesses, these can be very slow, see my warning here: https://docs.openvehicles.com/en/latest/userguide/scripting.html#vfs

Use the browser developer tools to analyse client performance. Btw, you can see the actual websocket packets when opening the network monitor before opening the web UI.

any similar use case / feedback from you ?

Thanks for any feedback.

Regards,
Michael

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