How to instantly seal parachain block with async backing?

Question

I encountered this error under --dev mode.

assertion `left == right` failed: slot number mismatch
  left: Slot(285901918)
 right: Slot(0)    
2024-05-11 15:11:48 1 storage transactions are left open by the runtime. Those will be rolled back.    
2024-05-11 15:11:48 1 storage transactions are left open by the runtime. Those will be rolled back.    
2024-05-11 15:11:48 ❗️ Inherent extrinsic returned unexpected error: Error at calling runtime api: Execution failed: Execution aborted due to trap: wasm trap: wasm `unreachable` instruction executed
WASM backtrace:
error while executing at wasm backtrace:
    0: 0x4f723d - <unknown>!rust_begin_unwind
    1: 0x15920 - <unknown>!core::panicking::panic_fmt::h7a368385936888dc
    2: 0x16440 - <unknown>!core::panicking::assert_failed_inner::h8608b548c883ea8f
    3: 0x40ffbb - <unknown>!core::panicking::assert_failed::h2f0ca201fdc74f98
    4: 0x3adc40 - <unknown>!<cumulus_pallet_aura_ext::consensus_hook::FixedVelocityConsensusHook<T,_,_,_> as cumulus_pallet_parachain_system::consensus_hook::ConsensusHook>::on_state_proof::h0fc8de67199d2e47
    5: 0x237ba3 - <unknown>!frame_support::storage::transactional::with_transaction::haf25409beb434094
    6: 0x1a8a6e - <unknown>!<cumulus_pallet_parachain_system::pallet::Call<T> as frame_support::traits::dispatch::UnfilteredDispatchable>::dispatch_bypass_filter::{{closure}}::h7de027a2a3b5a249
    7: 0x1b3e69 - <unknown>!environmental::local_key::LocalKey<T>::with::ha5fe1858700802dc
    8: 0x160eb3 - <unknown>!<pangolin_runtime::RuntimeCall as frame_support::traits::dispatch::UnfilteredDispatchable>::dispatch_bypass_filter::h2e7a00319cda07d7
    9: 0x155e25 - <unknown>!<pangolin_runtime::RuntimeCall as sp_runtime::traits::Dispatchable>::dispatch::h2cad3cd748893c87
   10: 0x4411ea - <unknown>!<fp_self_contained::checked_extrinsic::CheckedExtrinsic<AccountId,Call,Extra,SelfContainedSignedInfo> as sp_runtime::traits::Applyable>::apply::h12360671c174c9d3
   11: 0x3f1be5 - <unknown>!frame_executive::Executive<System,Block,Context,UnsignedValidator,AllPalletsWithSystem,COnRuntimeUpgrade>::apply_extrinsic::h81f7d0327e18a0d6
   12: 0x1db61c - <unknown>!BlockBuilder_apply_extrinsic. Dropping.    
2024-05-11 15:11:48 panicked at /home/bear/.cargo/git/checkouts/polkadot-sdk-cff69157b985ed76/c8d2251/cumulus/pallets/parachain-system/src/lib.rs:248:13:
set_validation_data inherent needs to be present in every block!    
2024-05-11 15:11:48 Proposing failed: Import failed: Error at calling runtime api: Execution failed: Execution aborted due to trap: wasm trap: wasm `unreachable` instruction executed
WASM backtrace:
error while executing at wasm backtrace:
    0: 0x4f723d - <unknown>!rust_begin_unwind
    1: 0x15920 - <unknown>!core::panicking::panic_fmt::h7a368385936888dc
    2: 0x4ae927 - <unknown>!<cumulus_pallet_parachain_system::pallet::Pallet<T> as frame_support::traits::hooks::OnFinalize<<<<T as frame_system::pallet::Config>::Block as sp_runtime::traits::HeaderProvider>::HeaderT as sp_runtime::traits::Header>::Number>>::on_finalize::h952e5e72e9ecc7d3
    3: 0x3b9fea - <unknown>!<(TupleElement0,TupleElement1,TupleElement2,TupleElement3,TupleElement4,TupleElement5,TupleElement6,TupleElement7,TupleElement8,TupleElement9,TupleElement10,TupleElement11,TupleElement12,TupleElement13,TupleElement14,TupleElement15,TupleElement16,TupleElement17,TupleElement18,TupleElement19,TupleElement20,TupleElement21,TupleElement22,TupleElement23,TupleElement24,TupleElement25,TupleElement26,TupleElement27,TupleElement28,TupleElement29,TupleElement30,TupleElement31,TupleElement32,TupleElement33,TupleElement34,TupleElement35,TupleElement36,TupleElement37) as frame_support::traits::hooks::OnFinalize<BlockNumber>>::on_finalize::h5bd89832c4727e0b
    4: 0x3f20ec - <unknown>!frame_executive::Executive<System,Block,Context,UnsignedValidator,AllPalletsWithSystem,COnRuntimeUpgrade>::idle_and_finalize_hook::h77b85e4cf31b58f8
    5: 0x1db76c - <unknown>!BlockBuilder_finalize_block    

I discovered this patch by Moonbeam.

https://github.com/moonbeam-foundation/polkadot-sdk/commit/9b36e2ab851bd836548d5b8d9daa053cb7d0da35

It's a patch for polkadot-v1.3.0.

Even in the most recent version of the polkadot-sdk(v1.11.0), I haven't found such an update. Is instantly seal officially supported by Substrate? If not, we'll need to set up a relay chain to get a local devnet running. Or cherry-pick the Moonbeam's patch.

Answer 1

If you look at the error:

assertion `left == right` failed: slot number mismatch
  left: Slot(285901918)
 right: Slot(0)   

Which is triggered here:

let relay_chain_timestamp =
            u64::from(RELAY_CHAIN_SLOT_DURATION_MILLIS).saturating_mul(*relay_chain_slot);

let para_slot_duration = SlotDuration::from_millis(Aura::<T>::slot_duration().into());
let para_slot_from_relay =
            Slot::from_timestamp(relay_chain_timestamp.into(), para_slot_duration);


assert_eq!(slot, para_slot_from_relay, "slot number mismatch");

The moonbeam fix is setting the relay_chain_slot in the proof. However, this:

sproof_builder.current_slot = (relay_parent_number as u64).into();

Should be:

sproof_builder.current_slot = (relay_parent_number as u64).into() / RELAY_CHAIN_SLOT_DURATION_MILLIS;

Generally the fix of moonbeam should be applied in polkadot-sdk directly.