Yes, Memcached can be used in a multi-threaded environment. In fact, it is designed to handle concurrent access from multiple client threads efficiently. Here's how Memcached supports multi-threaded usage:

Thread-Safe Implementation : Memcached servers are typically implemented to be thread-safe, meaning they can handle concurrent access from multiple client threads without data corruption or race conditions. Each client request is processed independently, ensuring thread safety.

Concurrent Connections : Memcached servers are capable of handling multiple client connections concurrently. Clients can establish connections to Memcached servers and send requests simultaneously, allowing for high concurrency and throughput.

Scalability : Memcached supports horizontal scalability by allowing multiple Memcached servers to be deployed in a cluster. Each server can handle a certain number of concurrent connections and requests, and additional servers can be added to the cluster to handle increasing load and scale out capacity.
Connection Pooling : Memcached client libraries often implement connection pooling to manage connections to Memcached servers efficiently. Connection pooling allows multiple client threads to share a pool of pre-established connections to Memcached servers, reducing overhead and improving performance.

Atomic Operations : Memcached supports atomic operations for certain data manipulation tasks, such as incrementing or decrementing numeric values stored in the cache. These operations are executed atomically, ensuring consistency and preventing race conditions in multi-threaded environments.

Client-Side Concurrency Control : Client applications can implement concurrency control mechanisms to manage access to Memcached in multi-threaded environments. Techniques such as locking, synchronization primitives, or transactional semantics can be used to coordinate access to shared data and prevent conflicts.