Gas limit when using multicall

[Uxio0]

Describe the bug
multicall sometimes exceeds eth_call gas limit and an out of gas error is raised.

To Reproduce
Do eth_call consuming the maximum gas allowed by the node. Library raises an exception. Example trace from the transaction-service:

2022-05-16 10:23:21,794 [WARNING] [MainProcess] https://safe-transaction.mainnet.gnosis.io/api/v1/safes/{address}/collectibles/ - Exception: NodeConnectionException - Data received {}
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/site-packages/gnosis/eth/multicall.py", line 227, in _try_aggregate
    result = self.contract.functions.tryAggregate(
  File "/usr/local/lib/python3.10/site-packages/web3/contract.py", line 957, in call
    return call_contract_function(
  File "/usr/local/lib/python3.10/site-packages/web3/contract.py", line 1501, in call_contract_function
    return_data = web3.eth.call(
  File "/usr/local/lib/python3.10/site-packages/web3/module.py", line 57, in caller
    result = w3.manager.request_blocking(method_str,
  File "/usr/local/lib/python3.10/site-packages/web3/manager.py", line 198, in request_blocking
    return self.formatted_response(response,
  File "/usr/local/lib/python3.10/site-packages/web3/manager.py", line 171, in formatted_response
    raise ValueError(response["error"])
ValueError: {'code': -32015, 'message': 'VM execution error.', 'data': 'Out of gas'}

Expected behavior
Reverts to use batch call

[007vasy]

@Uxio0 has a look at github.com/banteg/multicall.py if you want to fix it

[Uxio0]

Sorry @007vasy , what exactly do we have to take a look at?

[007vasy]

you can set the maximum gas and also multicall.py does a backtrack and tries to do the multicall with less amount of calls

[Uxio0]

Yeah, I mean, our biggest problem here is how to do it without impacting performance. Fallbacking to use less amount of calls after a failure is something we want to prevent

[007vasy]

my best guess is that some contracts are faulty and the functions are tagged incorrectly (a view function which is not tagged as view) therefore the node think it needs gas, but it does not (but that's just a guess)

[Uxio0]

Well, it's not just gas. For example, Erigon has an evm timeout of 5 seconds and gas does not matter too much. Gladly, in the new Erigon versions it can be configured

[DefiDebauchery]

The best option may be to hardcode exceptions for gas based on chain. It's relatively ugly, but it's the only way I've consistently been able to complete multicalls on chains with gas rules that are wildly different than norms.

[Uxio0]

Hi! I would be open to review it if you want to send us a PR, but I don't have buffer to take care of it now