If I get a full hash from a submitted tx, doesn't that mean the transaction is good?

Question

I am running a geth full node on Rinkeby and testing ERC20 transactions. Recently I submitted two transactions and received transaction hashes for each of them, so I assumed I was good. But later on when looking at the geth log, I realized that both transactions failed because I didn't give enough gas.

Here is a gist of the transaction log snippet:

https://gist.github.com/gojun077/276e342d0c17422816d28466d40aad11

My program logic assumes that receiving a full hash for a tx submission means that the tx was good. But as you can see from the geth log, at 08:30:14 I got a full hash but 1 second later at 08:30:15 the announcement was discarded by a Peer and the EVM returns err="out of gas".

The second transaction gets a full hash at 08:30:15 but it errors out 2 seconds later at 08:30:17 and doesn't make it into the block.

I then tried to search for these tx hashes but they were nowhere to be found, both locally and on Etherscan. Is this normal behavior? Is there a way to detect "out of gas" transactions programmatically, i.e. without tailing logs?

Answer 1

If you are writing a program which wants to ensure that a transaction has fully completed and will be permanently part of the blockchain, you should wait at least 2-3 additional blocks, and confirm your transaction still exists. I think 6 blocks is pretty normal for most applications which have sensitivity to these kinds of things.

If you are trying to make sure a transaction does not run into any errors during execution, it might be best to emit an event, and have a listener check for that event to know that execution happened successfully.