在计算机科学中，检查并设置（test-and-set-lock, TSL）是一种不可中断的基本（原语）运算。它会写值到某个内存位置并传回其旧值。在多进程可同时访问内存的情况下，如果一个程序正在运行检查并设置，在它运行完成前，其它的程序不可以运行检查并设置。中央处理器可使用可自行实作此指令，或利用其它电子组件如双端口内存（Dual-ported RAM）所提供的检查并设置机制。

以下则展示一种利用检查并设置指令来实现的锁：

当旧值为 0 时，这进程可以得到锁。否则的话，它会一直尝试将 1 写入内存位置，直到旧值为 0。

In computer science, the test-and-set instruction is an instruction used to write to a memory location and return its old value as a single atomic (i.e., non-interruptible) operation. Typically, the value 1 is written to the memory location. If multiple processes may access the same memory location, and if a process is currently performing a test-and-set, no other process may begin another test-and-set until the first process is done. CPUs may use test-and-set instructions offered by other electronic components, such as dual-port RAM; CPUs may also offer a test-and-set instruction themselves.