Bitcoin: What is the difference between the log messages “[validation] TransactionAddedToMempool” and “[mempool] AcceptToMemoryPool” when running debug=1?

Understanding Bitcoin Core Log Messages

When running bitcoin core, two specific log messages are printed to the console while in debug mode. These logs provide valuable insights into the functioning of the Bitcoin network. In this article, we will dive deeper into the differences between these two log messages and what they indicate when running Bitcoin Core version 28.0 with debug=1.

TransactionAddedToMempool

The first log message is:

[validation] TransactionAddedToMempool

This message is printed by the transaction-validation layer, which is responsible for verifying transactions on the blockchain. The [validation] tag indicates that this message is related to the validation of a transaction.

When a new transaction is added to the mempool (the pool of waiting transactions), it goes through several checks, including:

• Validation: Transactions are checked against several rules and conditions, such as checksums, script hashes, and data integrity.

• Sorting

  : Transactions are sorted based on their priority, which determines how quickly they can be broadcast to the network.

If a transaction passes these checks without errors, it is added to the mempool. This process continues until a valid transaction is found or all waiting transactions are rejected.

Mempool

The second log message is:

[mempool] ...

This message is printed by the mempool-operations layer, which is responsible for managing and handling transactions in the mempool. The [mempool] tag indicates that this message is related to mempool operations.

When a transaction is added to the mempool, it may need to be:

• Queued: Wait until it is available for mining.

• Forked: Become a new fork if the previous one fails or becomes orphaned.

• Bloom-forked: If the transaction was rejected by the validation layer and is not in a valid state.

These operations are performed to ensure that waiting transactions remain active on the network, preventing them from being lost forever.

Comparison and Conclusion

When running Bitcoin Core version 28.0 with debug=1:

• The first log message (TransactionAddedToMempool) indicates that a new transaction was added to the mempool for validation.

• The second log message (Mempool) shows operations related to transaction management in the mempool, including queuing, forking, or bloom-forking transactions.

In summary:

• [validation] TransactionAddedToMempool logs the initial addition of a transaction to the mempool for validation purposes.

• [mempool] ... logs transactions that require mempool operations, such as queuing, forking, or bloom-forking.

By understanding these log messages and their implications, you can better monitor Bitcoin network activity and optimize your performance when running Bitcoin Core.