High memory consumption in heavy coroutines

[marcoonroad]

Long-running/expensive coroutines (calling often await this.suspend()) will increase memory consumption due .demands() and .supplies() being not garbage-collected.

Possible solutions are:

• A flag (NO_STREAMS) during coroutine creation to avoid creating .demands() and .supplies() streams for heavy coroutines.
• Making .demands() and .supplies() not idempotent, they'll just return the latest stream point available. To get all coroutine's events, clients should call such functions early (e.g, before first .resume() call).

(Issue open to track further discussion)

[marcoonroad]

The former solution keeps backward-compatibility where the latter breaks it. Therefore, the first solution fits better as a bugfix patch, and the second solution can be deferred into next major release.

[marcoonroad]

The solution was 3 modes:

• PERSIST, the default mode.
• DISABLE, the former mode on original post.
• COLLECT, the latter mode on original post.

No backward compatibility broken! 🎉