feat: add memory-spike plugin

[naugtur]

it took going on holiday again, but here it is

open questions:

• not sure what the expectation is on report string and which is more important for a plugin's end user - report or result
• I don't enjoy having to normalize the measurements by dividing them into potentially small numbers and aggregating again' but that's how the benchmarking loop is designed and I understand having a before and after hook for an entire case in a suite may not be feasible
• is adding a global reference to __recordMemorySpike going to cause trouble in workers?
• how do you like the test? It's the first plugin with a test

[RafaelGSS]

Instead of creating a function inside globalThis, I'd add all the context into the beforeClockTemplate. Also, I wouldn't perform memory translations during the collect process, instead, you can do it textReporter. Just check if bench.plugins includes this new plugin.

[RafaelGSS]

This shouldn't be here, right?

[naugtur]

I wanted to brainstorm what to produce as the report - or is producing results enough? If we get it right, the report might be nice tho.

[RafaelGSS]

This function is called by the reporters, and it should return a string in case you want to show it there. See on textReporter

[RafaelGSS]

We should mention folks that are going to use it will need to pass --expose-gc

[RafaelGSS]

I'd also mention a possible performance inconsistency when this plugin is enabled due to GC blocking op.

[naugtur]

I'm only calling gc in oncomplete, which I assumed is not part of the span that is being measured. is that incorrect?

[naugtur]

Instead of creating a function inside globalThis, I'd add all the context into the beforeClockTemplate.
My assumption was it'd cause the initialization of the whole thing to be included in the measurement.
From your comments it seems before and after are not in the measured time span but oncomplete is. that's surprising.

Also, I wouldn't perform memory translations during the collect process, instead, you can do it textReporter. Just check if bench.plugins includes this new plugin.
can do

[RafaelGSS]

@naugtur would mind if I take over this PR?

[naugtur]

I wouldn't mind that. I'm going on vacation next week so might have some time to put into it again, but trat time might as well go into reviewing and testing out your changes.