LibraryCaches

LibraryCaches is a system component that stores metadata about dynamic libraries to speed up loading and binding at runtime. It typically functions as a cache of library locations, versions, and dependencies, managed by the operating system’s dynamic linker or runtime loader. By keeping ready access to where libraries reside, the cache reduces directory scans and repeated dependency resolution during application startup.

Operation and behavior: When an application starts, the linker consults the LibraryCaches to locate necessary libraries quickly and to ensure correct symbol binding. The cache may include dependency graphs and version information to prevent mismatches. It is invalidated or rebuilt whenever libraries are added, removed, or updated, ensuring subsequent launches reflect the current system state.

Platform examples: Linux maintains a shared cache at /etc/ld.so.cache, generated by ldconfig from configured library paths. macOS uses the dyld shared cache to prebind and accelerate binding of system libraries. Other platforms may implement per-process caches or alternative global caches with similar goals.

Security and reliability: Cache validity is crucial; stale entries can lead to failed loads or incorrect bindings. Systems typically refresh caches during package installations, system updates, or explicit maintenance commands and may employ integrity checks or signatures to mitigate cache poisoning.

Management considerations: Cache generation and refresh are usually automated but can also be triggered manually via dedicated tools (for example, a cache builder or system update process). Proper cache invalidation policies help balance startup performance with correctness, especially on systems with frequent library updates.

See also: Dynamic linking, Shared libraries, ld.so.cache, dyld.