Solana Client Developer Jito Announces End of ‘Mempool’ Function

The developer of popular alternative Solana client Jito on Friday abruptly pulled the plug on its mempool functionality, a key part of its tech stack that had nonetheless enabled a spate of costly sandwich attacks on traders.

Jito Labs said in a tweet Friday that the mempool function would go offline tonight. Mempools are the place where on-chain transactions sit before they’re added to the blockchain. Solana doesn’t have a mempool but Jito’s method for transaction ordering did.

The decision marks a turnabout for Jito, which just two weeks ago un-banned the practice of “front-running” after deeming the restriction unenforceable, according to messages in its Discord server.

Front-running is a layman’s way of describing the practice of “sandwich attacks” in which trading bots take advantage of transactions which have been added to the mempool but not yet executed. Before they get a chance to, the bot “sandwiches” the trade to extract value from the trader.

Jito builds and manages an alternative client for processing transactions on the Solana blockchain. Over half of validators used it at last check.

Representatives for Jito did not return a request for comment.