TLDR Tech / DevOps
ZGateway: Learnings from Putting a Proxy in Front of ZippyDB
ZGateway is a proxy tier that sits between clients and ZippyDB, Meta's most widely used key-value store. The system handles more than 1 billion operations per second and carries about 40% of ZippyDB traffic, adding roughly 6% computational overhead. The core problem it solves is connection sprawl: under direct access, a million-plus client hosts each maintained tens of thousands of TLS connections to database hosts, creating a many-to-many mesh that caused file-descriptor exhaustion and reboot loops during reconnection storms. By routing all traffic through a controlled proxy fleet, Meta reduced total persistent connections by roughly 19x and made fan-in independent of client population size.
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