Don't miss Build Games$1M Builder Competition

Streaming Asynchronous Execution

ACP-194 decouples consensus from execution, enabling parallel processing and dramatically improving C-Chain throughput.

Streaming Asynchronous Execution

ACP-194: Decoupling Consensus and Execution

Traditional blockchains have a bottleneck: consensus waits for execution, execution waits for consensus.

What if they could run in parallel?

01
The Bottleneck
Synchronous Execution
Consensus
Execution
Verification
TIME

Execution fragments consensus. The proposer runs the VM before proposing. Every validator re-executes to verify — a complete repeat of execution. The dashed lines represent verification: validators must fully re-run the VM to confirm correctness. Execution happens twice per block, yet only one result matters.

Transaction Lifecycle*all animations are simplified for illustrative purposes
Transaction
Block
Execution
Consensus
Context Switching
Mempool
Block Building
Executing
Accepted

Execution blocks everything. The proposer executes before proposing. Every validator re-executes to verify. Consensus pauses for the VM, the VM pauses for consensus. Block N+1 cannot start until Block N fully settles.

02
The Solution
Transaction Lifecycle*all animations are simplified for illustrative purposes
Transaction
Block
Execution
Consensus

Consensus Stream

Mempool
Forming
Block Building
Validating
Accepted

FIFO Queue

Out
Empty
In

Execution Stream

Waiting
Executing
Results

Consensus orders transactions and validates gas payment without running the VM. The queue buffers accepted blocks while execution drains them. Results stream to clients immediately as each transaction completes.

Streaming Asynchronous Execution (SAE)
Consensus
Execution
Block
Settlement
TIME

Two streams running in parallel. Consensus accepts transactions into a queue. Execution drains it. No waiting, no blocking. Every accepted transaction executes — gas bounds validated at acceptance. Results stream to clients immediately. Settlement follows 5 seconds later.

Assembly Lines, but for Blockchainsblockchain go brrr
Consensus
FIFO Queue
Execution
🔥
Firewood
STATE ROOT
ExecutedSettled

Faster block acceptance. Saturated execution. Instant receipts.

03
Key Features

Gas is the clock.

ACP-176 introduced the gas rate R = 30M gas/sec. SAE uses R to convert gas consumed into elapsed time.

0M
gas
÷
30M
gas/sec
=
0ms
time
R = 30M gas/sec → gas consumed = time elapsed

Budget for worst case, pay for what you use.

If you can cover the maximum possible cost, your transaction is guaranteed to execute. You only pay for actual gas used.

Gas Limit200k
× Worst Price25 nAVAX
Worst Case0 AVAX
Balance
0
Worst Case
0
Can cover worst case → accepted → guaranteed to execute

See results instantly.

Get transaction results the moment they execute — no waiting for settlement.

Fast DeFiInstant payments

Two engines, full speed.

Consensus and execution run in parallel. No more waiting for one to finish before starting the other.

Consensusraces ahead
Executioncatches up
04
The Payoff

What this enables

When paired with Simplex and DKG (Distributed Key Generation)

Real-time VRF

Consensus artifacts become available during execution. Expose a verifiable random function for provably fair on-chain randomness.

Consensus
seed:0x7a3f...
VRF
rand:0x9c2e...
generating...

Encrypted mempool

Sequence transactions before revealing contents. Front-running and MEV extraction become significantly harder.

Mempool Queuesequence → reveal
swap
encrypted
executed
✓ front-running blocked

*Streaming async execution is required to implement these features.

FAQ

Is this guide helpful?