Slow debugger in remote mode

[jeffutter]

Problem description

It seems that Byebug.start_server at the top of my (sinatra) application causes near 30x performance regressions in some cases.

A certain query which fires off a bunch of DataMapper queries and returns a ton of JSON executes approximately 30x slower when a byebug server is started (with no clients connected)

Expected behavior

I would expect no performance penalty, particularly if no client is connected.

Actual behavior

The given endpoint benchmarks (with wrk) 30x slower.

Steps to reproduce the problem

Unfortunately, the code isn't open source. I can try to create a small reproduction scenario, first, though, I was wondering if this is known/expected? Perhaps my assumptions about performance are incorrect?

[deivid-rodriguez]

Your assumptions are partially right. The debugger is supposed to have a performance penalty for sure, but in this particular case (no clients connected), it shouldn't happen and it's a bug.

This is what's left to be fixed from #144. Will close that issue and keep progress here. Also changed the title a bit, since what's serious and what's not is a bit subjective ;)

[jeffutter]

Ahh, good to see it's a known issue and not just me. I don't think I have much time to dig into this, but if there is any info I can provide, please let me know.

[maximderbin]

The same issue for me

[deivid-rodriguez]

Hi @jeffutter, @maximderbin and "plus-oners", this should be fixed by #406, feel free to give that branch a try and let me know. Thanks!

[jeffutter]

@deivid-rodriguez I'm no longer on a project where I need to use remote mode so I probably won't be able to give it a try. Hopefully, someone else can chime in. Thanks for the hard work though.

[deivid-rodriguez]

@jeffutter No problem at all, thanks for the kind words anyways!