The Redis search engine module, RediSearch, aims to provide fast and feature-rich real-time search capabilities while maintaining the simplicity of Redis' single-threaded architecture. However, this simplicity comes with a cost: long-running commands can block the entire server for extended periods. To address this challenge, Salvatore Sanfilippo introduced Thread Safe Contexts and the Global Lock in Redis 4.0, allowing modules to run multiple threads while acquiring the lock when accessing or modifying data. This enables concurrency without sacrificing atomicity of reads and writes, although some limitations apply, particularly with high update/delete loads. The new design allows for concurrent execution of queries and indexing, improving performance and making RediSearch a more powerful search engine suitable for large datasets and high loads.