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

Understanding Bitcoin Core Log Messages

When running bitcoin core, two specific log messages are printed to the console in debug mode. These logs provide valuable information about the functioning of the Bitcoin network. In this article, we will dive into the differences between these two log messages and what they mean 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 in the blockchain. The [validation] tag indicates that this message is related to transaction validation.

When a new transaction is added to the memory pool (pool of pending transactions), it goes through various checks, including:

• Validation: Transactions are validated against a number of rules and conditions, such as checksums, script hashes, and data integrity.

• Sorting

  : The transaction is sorted based on a priority that determines how quickly it can be broadcast over the network.

If the transaction passes these checks without errors, it is added to the memory pool. This process continues until a valid transaction is found or all pending transactions are discarded.

Memory Pool

The second log message is:

[mempool] ...

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

When a transaction is added to the memory pool, it may need to:

• Queued: wait until it is available for mining.

• Forked: become a new fork if the previous one fails or is 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 pending 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 has been added to the memory pool for validation.

• The second log message (Mempool) shows operations related to managing transactions in the memory pool, including queuing, forked, or bloom-forked transactions.

To summarize:

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

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

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