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## Problem Prefetch is performed locally, so different backers can request the same pages form PS. Such duplicated request increase load of page server and network traffic. Making prefetch global seems to be very difficult and undesirable, because different queries can access chunks on different speed. Storing prefetch chunks in LFC will not completely eliminate duplicates, but can minimise such requests. The problem with storing prefetch result in LFC is that in this case page is not protected by share buffer lock. So we will have to perform extra synchronisation at LFC side. See: https://neondb.slack.com/archives/C0875PUD0LC/p1736772890602029?thread_ts=1736762541.116949&cid=C0875PUD0LC @MMeent implementation of prewarm: See https://github.com/neondatabase/neon/pull/10312/ ## Summary of changes Use conditional variables to sycnhronize access to LFC entry. --------- Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>