api/exec await + latex

[haraldschilly]

Description

• coming up with the right semantics to start, get and await an async job

• using this to enhance latex document compilation. this is way harder than I hoped for :-( ... the more I debug, the more problems come to the surface.

  • the hardest bug was a case, where a process that exits in a forced way (e.g. kill) has no exit code. Then, the backend never returns, leaving the callback chain hanging. So, this is now fixed, because the exit code falls back to 0 in that case.

• this fixes simple tikz error causes latex build to hang with no easy way to kill running latex job (problem is that you can't easily kill it) #3783 by letting users click a stop button if there is no progress

  Here is how this looks after >15 seconds. Of course, there is no indication why. The log stops and cpu is high. More informative than before.

  

• after compilation is done, this adds peak known memory usage and duration at the top of the logs.

  

Checklist:

• Testing instructions are provided, if not obvious
• Release instructions are provided, if not obvious

[haraldschilly]

This is by far not perfect, but it is definitely a step forward.