Octoprint: Unregular ValueError during analyzation of gcode

[christianlupus]

What were you doing?

I simply sliced a STL file in Slic3r and made a automatic upload to the OP server.

What did you expect to happen?

The file gets accepted and the server continues to run.

What happened instead?

From time to time, the OP server renders itself unresponsive after a short period of time after the upload. This happens (unfortunately for the debugging) not deterministically. At least I did not find any indicator when it happens.
I have the intuition that it happens more frequently if the OP server did some printing before. A clean restart from SSH often solves the problem.

When monitoring the pi after an upload, I see an additional process in the list of threads of OP that seems to analyse the gcode:

/home/printer/OctoPrint/virt/bin/python2 -m octoprint analysis gcode <...>

This process must terminate before I start printing. Either it succeeds, then I can start printing. Sometimes it seems to fail. (I will attach an log of OP.) Then the complete OP server stalls and is no longer reachable. I can only kill the individual subprocesses of OP and at some point OP will shut down. However this will ruin any running print.

When looking into the logs live during such a failure, every ~30 seconds a message about an unknown format code appears (see log). The CPU load drops to about nothing. The whole OP server seems to wait for an external event that cannot/will not happen.

Did the same happen when running OctoPrint in safe mode?

I cannot try as I would have to run OP in safe mode continuously to test if it was an issue. This is not a good idea in a "productive" environment.

Version of OctoPrint

1.3.9rc1 (fdf0f75ffa5731fee406c6e761e84a9d2b47aa43)

Operating System running OctoPrint

Raspbian jessie

Printer model & used firmware incl. version

Zonestar Q802N

Browser and version of browser, operating system running browser

Linux, Firefox 60.0.2

Link to octoprint.log

https://gist.github.com/christianlupus/7b84b4fe0ac4dfd68c9235f617a4e010

Link to contents of terminal tab or serial.log

Not a communication problem with the printer but inside OP. Thus no serial logs attached.

Link to contents of Javascript console in the browser

OP server is completely unresponsive. Thus no logs here.

Side remarks

I recently updated to the 1.3.9 RC. I do not know if this error here is related to #2688.

I have read the FAQ.

[foosel]

That ValueError you are seeing there doesn't come from OctoPrint itself but rather the DetailedProgress plugin you have installed.

I'm unsure if this can be the cause here, but just to make sure, could you disable that and see if the issue still shows up? I know it's tricky to reproduce, but I certainly have never seen it myself, so I must rely on your feedback here.

[christianlupus]

OK, I disabled the plugin now. I know that it is bad to have a non-deterministic problem and no clue. This is why I tried to explain so much in the section "what happens".

I will have a closer look if the issue persists, however this will take some time. I finished printing the parts for my current project last night and next I need to focus on other parts of it, so the printer will be used less in the near future, I fear.

To avoid scattering your issue list, I will assume, that the plugin is responsible and close this issue for now (reopen if I find the problem unrelated to the plugin).