Distillery changing +Q to -Q from vm.args?

Questions / Help
1

I have some changes in my vm.args file:

+Q 134217727
+K true

but when I look at the line in top it shows -Q 134217727 -K:

{beam.smp} /opt/app/releases/0.1.2/app.sh -Bd -Q 134217727 -K true -- -root /opt/app -progname ... etc

Is this working as expected?

2

Try checking if +Q flag worked:

:erlang.system_info(:port_limit)

If it returns around 65536, it didn’t.

I think +K is no longer used (as of version 21).

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3

Weird that worked… ok nice!

What other settings are good to tune in vm.args?

4

There are two kinds of flags in vm.args - the emulator flags that end up being passed down to the runtime itself and “user flags” - things like boot arguments or application env - they are consumed by the erlang system. The first kind is passed in vm.args with + prefix, the second with -. The shell consumes both flags and ends up translating the emulator flags to be prefixed with - before being passed to the emulator itself.

4 Likes
5

Great explanation, thank you

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