What Happens If the Mempool Gets Full on the Bitcoin Blockchain?
Before any Bitcoin transaction can be added to the blockchain, it must first wait in the mempool, the node’s repository for all pending transactions.
Mempool space may vary between nodes depending on network traffic, leading to longer confirmation times and higher priority fees for miners.
What is the mempool?
The mempool is an integral component of blockchain transactions, serving as an unconfirmed transaction repository until they can be included in a block for validation and inclusion in new blocks. Unfortunately, as any system can become overburdened with transactions and consequently increase fees incurred by users; understanding its functioning and how best to respond if your mempool fills up quickly are essential knowledge for cryptocurrency users.
As soon as you send or receive Bitcoin, your transaction will first be placed into the mempool. Unlike traditional stock trades, Bitcoin transactions don’t go through an organized clearinghouse and instead each node in the network verifies and adds the proposed transaction to their mempool before miners retrieve these from there to process and confirm them as part of a new block on the blockchain.
As is to be expected when there’s heavy network activity, the mempool can quickly become congested. But its dynamic nature means transactions in it are prioritized according to their fee rates – with higher fee transactions more likely being included in new blocks and confirmed quicker than lower fee transactions.
Mempool size can also serve as an indicator of transaction activity, with larger mempool sizes signalling increased transactions awaiting confirmation and potentially signalling an increase in network traffic; on the other hand, smaller mempool sizes might indicate that miners aren’t processing new blocks as quickly.
Each node will maintain their own mempool, keeping track of its size and status independently while also communicating with other nodes to ensure all are aware of which transactions have been added to the mempool as well as any associated fee rates.
Nodes usually notify other nodes when they’re ready to mine a block, and those other nodes will then remove it from their mempool and add it into their blockchain, clearing out transaction queues of those nodes waiting on it and helping prevent traffic jams and ensure transactions are confirmed on time.
What are the benefits of using mempool.space?
The mempool is used by bitcoin blockchain nodes to ensure that priority, low fee transactions are processed first and that there are enough resources available to process all pending transactions. By default, each node’s mempool size is set at 300MB; once this limit has been filled up with transactions with lower fees will be dropped – that is shown by pink bars in the chart above; had they decided to increase this by 30 blocks then those transactions would appear purple bands on it instead.