How Meta Achieves 99.99999999% Cache Consistency 🎯

Meta has developed a system to achieve 99.99999999% cache consistency, essential for scaling distributed systems. They use an observability solution featuring Polaris to monitor and detect cache inconsistencies and a tracing library to log data changes during race conditions. This approach allows querying the database at controlled intervals to prevent overload and find inconsistencies quickly. These techniques ensure only 1 out of 10 billion cache writes become inconsistent.