Ponyc: --ponyminthreads is confusing

[SeanTAllen]

It doesn't control the number of threads. It sets a floor for scaling threads. So if I set 999 it won't create 999 threads, it will not scale LOWER than 999 threads. So if --ponythreads is less than --ponyminthreads no downscaling will occur.

Options:

• better help description
• better flag name

Thoughts?

[SeanTAllen]

From sync. We believe there should be a flag for "don't scale my threads".

And --ponyminthreads will error out if it is greater than --ponythreads.

--ponynoscale is the current idea for turning off scaling.

if --ponynoscale is used on application startup then it should be a startup error to use --ponyminthreads.

[rhagenson]

@SeanTAllen If I am understanding this correctly the changes needed are:

• [ ] Clarify use and interaction of --ponyminthreads and --ponythreads
• [ ] Add a --ponynoscale flag that errors if used with --ponyminthreads

Should this --ponynoscale flag be the same as stating --ponyminthreads=0?

[SeanTAllen]

@RHagenson Not quite.

--ponynoscale is the same as setting --ponyminthreads equal to the value of --ponythreads. That is, it will never try to scale down the number of scheduler threads. Whereas --ponyminthreads=0 will allow you to scale all the way down to no scheduler threads running.

As part of this, we need to confirm that --ponyminthreads <= --ponythreads. If it isn't it should error out.

Documentation would need to be updated accordingly.

[rhagenson]

Got it. I had --ponyminthreads=0 in my head as a special value rather than an actual possibility of zero scheduler threads running. Good to know that is possible (not sure when it is useful, but not a major concern right now).

[SeanTAllen]

@alexsnaps has a PR open for this #3303.