Perf of dereference is unstable

[P0lip]

See APIDevTools#211

[billiegoose]

Wait, so you fixed the performance by removing protection against circular references?

[P0lip]

Nope!
It's just a redundant check that didn't seem to have any actual impact on perf.

https://github.com/stoplightio/json-schema-ref-parser/blob/55dee7ed978b734a1fd354e01197236b3eaa106c/lib/dereference.js#L108L126 is what actually made impact. That added check didn't contribute.

For a context this is the change I'm talking about 5c3eece
I just didn't notice options.dereference.circular === "ignore" || processedObjects.indexOf(obj) === -1) changing anything so I reverted to the initial version of this code (prior to the aforementioned commit)

[P0lip]

We may potentially just use a bit more conservative change that was implemented here APIDevTools#212
It only swapped arrays with sets, but this already mitigated the perf cliff.

[P0lip]

https://github.com/stoplightio/platform-internal/issues/5517 reminded me about this
Since the $ref has mid in it, and masking = dereferenced output, they might be encountering this issue.
This would actually align with what Em said in the linked ticket - the whole process took a bit over a minute in case of the file he dealt with.

[chohmann]

@P0lip if https://github.com/stoplightio/platform-internal/issues/5517 is caused by this, can I assign that ticket to you guys?

[domagojk]

It looks good. If it was a redundant check then can't complain about removing it :)
Just remove a jsdoc comment for processedObjects, but it's approve from me 👍