parathreads

Parathreads are a mechanism in the Polkadot ecosystem that lets developers connect a project to the relay chain without securing a full parachain lease. They function as on-demand execution threads that share the relay chain’s block space, rather than occupying a dedicated, long-term lease.

How parathreads work according to the protocol: developers register a parathread and submit its data to a parathread pool. Each relay-chain block can include a limited number of parathread commitments, and inclusion is not guaranteed. Parathreads operate on a pay-as-you-go model, typically paying per block to be included in the chain’s runtime execution. Scheduling and priority are influenced by fees and network demand. If a parathread is not included in a given block, it remains in the pool for future scheduling.

Relationship to parachains: parathreads are designed as a lower-cost entry point compared to acquiring a dedicated parachain lease. They enable testing, development, and early deployment of cross-chain functionality. If a project later wins a parachain lease via auctions, its parathread can graduate to a traditional parachain, inheriting a permanent slot. Conversely, existing parachains can operate alongside parathreads for flexible resource use.

Use cases and considerations: parathreads are suitable for MVPs, experimental features, and ongoing development that require live cross-chain interaction without a long-term commitment. They offer faster onboarding and lower upfront costs, but they do not guarantee execution in every block and depend on relay-chain capacity and fees.