error thrown from sleep: attempt to call a userdata value

[pspacek]

Occasionally I receive mystical errors from cqueues:

error: attempt to call a userdata value stack traceback:
	[C]: in function 'poll'
	/usr/share/lua/5.1/cqueues.lua:62: in function 'sleep'
	/usr/lib/knot-resolver/kres_modules/prometheus.lua:91: in function </usr/lib/knot-resolver/kres_modules/prometheus.lua:39>

This happens asynchronously and I cannot see any explanation in my code, it just calls sleep.

The only wild idea that came to my mind is a problem with premature termination of syscalls but I do not have sufficient knowledge of cqueues and coroutines to dig deeper.

Any ideas what it might be and how to fix that?

[daurnimator]

I'd probably start by printing off the stack just before the lua_pcall?

[pspacek]

Hmm, I do not undestand what you mean. My code is calling .sleep(1) ... do you mean adding a pcall to someplace in cqueues?

[daurnimator]

do you mean adding a pcall to someplace in cqueues?

cqueues/src/cqueues.c

Line 1638 in 813664c

if (LUA_OK != (status = lua_pcall(L, 1, 1, 0))) {