Definition
Plain language
A database strategy where you lock each thing before touching it and hold all your locks until you're done, making everyone else wait.
As stated in the literature
2PL — a pessimistic concurrency-control protocol that acquires locks before access and releases them only at commit, guaranteeing serializability at the cost of waiting and potential deadlock; for long agent transactions, locks held for minutes stall peers.
Also called: 2PL
Why it matters: It reliably prevents conflicting operations from corrupting data, but for long-running AI tasks the lengthy waits and risk of deadlock can stall everyone else.
For example, before changing an account balance, a transaction locks that account and holds the lock until it fully finishes, forcing any other transaction touching it to wait.
Heard on the show
“The first is pessimistic — two-phase locking, usually written as 2PL.”Episode 150 — Don't Kill the Loser: A Different Way to Handle Two AI Agents Colliding