**UPDATE: Please be so kind to reject this proposal, the team has included the heap pages increase on an upgrade and this seems to be the best way to approach the issue.**

---

We’ve noticed that some validator nodes on polkadot, encounter a “allocator failed to allocate memory” error around the time when the staking election (phragmen) is being computed. Recall that this computation is happening in an **offchain worker thread**. Nonetheless, in the current implementation, the offchain worker thread, which itself is executed in WASM, uses the same WASM environment as the canonical runtime, and therefore has limited memory. To prevent the situation where no validator submits an election solution, the amount of memory accessible to the offchain worker environment should be increased.

Note that ideally, this change should only affect the offchain worker thread, and not the main runtime. But as mentioned, currently they share the same configurations. A long term solution is to separate these configurations and only increase the amount of memory that is accessible to the offchain worker ([PR](https://github.com/paritytech/substrate/pull/8885)). But, since this is not readily possible, we opt to propose increasing the overall WASM runtime memory pages, which affects both block execution and offchain worker. We expect this decision to have **no notable effect** on the main runtime’s progress and execution.

The amount of memory available to WASM is determined in the number of “pages of memory” that can be allocated in the called, aka. “**Heap pages**”. This value lives on-chain, and you can inspect it similar to other [well-known-keys via “:heappages](https://github.com/paritytech/substrate/blob/28107d402cb88cf50119c4ecb16555fcacf3a3e6/primitives/storage/src/lib.rs#L166)”. Currently, no value is set there and a [default of 1024](https://github.com/paritytech/substrate/blob/ef0e22e11535abaa393122209f83ed02a068a464/client/executor/src/native_executor.rs#L48) is used.

More info can be found [HERE](https://docs.google.com/document/d/12CFQlgBxWwBOcpyoJiNhifvAoPQKBDej9f3YRf9Moq8/edit?usp=sharing). This proposal is a temporary solution, Kian from Parity is working on a permanent fix [here](https://github.com/paritytech/substrate/pull/8885).

Preimage for the motion [HERE](https://drive.google.com/file/d/1p1gQKqzYKo2CL-GrsZI2qNonH_kwGZXG/view?usp=sharing).

 Set the number of pages in the WebAssembly environment's heap.

 # <weight>
 - `O(1)`
 - 1 storage write.
 - Base Weight: 1.405 µs
 - 1 write to HEAP_PAGES
 # </weight>

:

1. Validator nodes encounter an “allocator failed to allocate memory” error when the staking election (phragmen) is being computed.
2. The amount of memory accessible to the offchain worker environment needs to be increased.
3. Long-term solution is to separate configurations, but for now, increasing overall WASM runtime memory pages is the best approach.
4. The amount of memory is determined in "heap pages" and currently the default is 1024.
5. Parity team is working on permanent fix.
6. Precompiled image of the motion is available.

#24 Increasing the WASM heap pages.

No Active Proposals