[Bug] MempoolManager.new_peak() fails in case of a re-org where the new tip is not a transaction block

[madMAx43v3r]

What happened?

In case of a re-org, MempoolManager.new_peak() is only called with the new peak, however the function early exits if the given peak is not a transaction block:

chia-blockchain/chia/full_node/mempool_manager.py

Line 622 in cd78dba

if new_peak.is_transaction_block is False:

As such the mempool is not updated correctly in case of a re-org where the new peak is not a transaction block. Only at the next transaction block it will be corrected.

Version

master

What platform are you using?

Linux

What ui mode are you using?

CLI

Relevant log output

No response

[wjblanke]

Thanks Arvid will take a look

[arvidn]

It's not immediately obvious what the best approach to fixing this is. Maybe we could back-track to find the most recent transaction block to see if it matches the current peak.

Another approach, that might be simpler, would be to update self.peak every time we see a block, including non-transaction blocks. That way, a (non-tx) block that doesn't follow in the chain could trigger the mempool reorg

[arvidn]

the mempool doesn't have the ability to traverse the blockchain. If it gets a non-tx block that's disconnected from its current peak, it can't step back to find the most recent transaction block.

I think this issue has to be fixed in full_node.py and make sure it only passes transaction blocks to mempool_manager.new_peak()

[arvidn]

I'm addressing this issue here: #17370

[wjblanke]

Thanks for the report!