How to execute a runtime upgrade that takes more weight than one block can hold

Question

I'm trying to execute a runtime upgrade on a running parachain. I'm using the cumulus parachainSystem pallet to do, using the authorize -> enact flow.

My parachain have the contracts pallet, with the standard migration.

The steps I'm doing are the following:

1. I'm just modifying the spec_version, without adding or removing any pallet.
2. Then I run cargo build --release -p <runtime pkg> to build the new runtime blob.
3. To execute the authorize_upgrade, I get the smallest file generated by the command above. Which the file name is something like <runtime pkg>.compact.compressed.wasm
4. I execute the enact_upgrade call, and here is where the problem starts!

I've got mixed outputs, doing with and without the scheduler pallet.

It outputs this error first: And it tries to collate over and over until the error Import failed: State Database error: Too many sibling blocks inserted start appearing.

I've tried using the scheduler already, but I'm probably doing something wrong? How can I properly set the scheduler with the auth -> enact flow, to successfully execute the runtime upgrade in the parachain?

I'm calling using sudo, like this:

The steps I'm doing:

The upgraded runtime just have the spec_version increased, no pallets removed/addded.

1. Scheduled a authorize_upgrade call, to be executed in n+5 blocks.
2. Waited the execution of the n+5 block.
3. After, scheduled the enact_authorizeto be executed in n+10.

When the second scheduled call happens, it keeps starting collation until the too many siblings error starts popping up.

Is the order right? Do I need to make a set_code call in the Parachain, before or after the auth/enact?

Answer 1

Looks like your migration is "too long". You may need to try a different migration strategy.

More on this can be found here:

• https://docs.substrate.io/reference/how-to-guides/parachains/runtime-upgrade/#choose-your-upgrade-approach