On-demand Parachains

[eskimor]

On-demand parachains are the first variant of a more dynamic block space 8 acquisition method. Parachains, how they exist now, offer a very static way of acquiring block space: You win an auction and have block space secured over a long period of time, e.g. a year. Currently you would be allowed (and expected) to author a block every 12 seconds for that entire duration.

This guaranteed ability to author blocks at regular intervals is indeed a requirement for some applications/chains and is one of the features making Parachains superior compared to smart contracts.

But on the flip side there are also applications for which this is overkill, making them a Parachain would result in lots of wasted resources from the perspective of the network. From a user perspective, winning an auction is quite some barrier to entry, making it harder for new projects and ideas to join the network. With on-demand Parachains we both lower that barrier and open up the network to less demanding applications in a network efficient way.

So how does this work? An on-demand Parachain is not scheduled for block authorship every twelve seconds, but instead a collator orders a core (a block authorship opportunity) when there is a need. For this, collators will send an extrinsic saying that they want a core for their ParaId containing a maximum price they are willing to pay.

Describing blog post here.
Meta ticket: paritytech/polkadot-sdk#828
Board: https://github.com/orgs/paritytech/projects/67/views/1
Feature Branch: paritytech/polkadot#6969

• Q2 Milestones
  • Launch feature (without cumulus integration) on Rococo
• Q3 Milestones
  • Launch on Kusama Q3 2023
    • All security tickets are handled
    • Security audit happened
    • integrated with asynchronous backing + look ahead
  • Cumulus Integration
    • ordering strategies implemented in cumulus
    • example parachain making use of those
    • running on Rococo