race condition in new headers subscription

[pata-eth]

System information

Erigon version: 3.3.0

OS & Version: linux

Chain/Network: gnosis

Expected behaviour

calling any relevant endpoint with the block number from the event should not fail

Actual behaviour

occasionally, calls fail with error 'request beyond head block: requested X, head X-1

Steps to reproduce the behaviour

import asyncio

from web3 import AsyncWeb3, WebSocketProvider


async def main():
    rpc_url = "wss://rpc.gnosischain.com/wss"

    async with AsyncWeb3(WebSocketProvider(rpc_url)) as w3:
        _ = await w3.eth.subscribe("newHeads")

        async for block_header in w3.socket.process_subscriptions():
            block_number = block_header.get("result").get("number")
            print(f"Block {block_number} announced via subscription")

            # Immediately try to call eth_feeHistory with this block number
            try:
                _ = await w3.eth.fee_history(  
                    block_count=10,
                    newest_block=block_number,
                    reward_percentiles=[20],
                )
                print(f"✅ eth_feeHistory succeeded for block {block_number}")
            except Exception as e:
                error_msg = str(e)
                print(
                    f"❌ eth_feeHistory FAILED for block {block_number} {error_msg}"
                )


if __name__ == "__main__":
    asyncio.run(main())

[VBulikov]

yperbasis added Imp2 as Importance

[Giulio2002]

Attempted to reproduce on a fully-synced Gnosis archive node (Erigon v3.4.0-dev) using the exact script from the issue description (adapted to local WS endpoint).

Results: 50/50 blocks PASS — 0 failures.

Subscribed to newHeads, then immediately called eth_feeHistory(newest_block=N) for each block N received. All calls returned successfully in ~1ms. No request beyond head block errors observed.

probably fixed already!