Does SQLite ensure safe execution of operations in a multithreaded environment?

SQLite supports several threading modes that affect the safety of operations in a multithreaded environment:

• Single-thread — SQLite is not protected against concurrent access from multiple threads. It should not be used in a multithreaded application.
• Multi-thread — the same database object can be used in different threads, but not simultaneously. Access must be synchronized manually.
• Serialized — SQLite provides full thread safety, allowing multiple threads to safely execute queries simultaneously.

By default, SQLite is compiled in Serialized mode, which ensures safe operation in a multithreaded environment without additional synchronization. However, in iOS applications, it is often recommended to use separate database connections for each thread or to use queues (e.g., DispatchQueue) for sequential access to avoid blocking and improve performance.