Peterson's 1981 two-process algorithm showed that mutual exclusion could be expressed with only ordinary shared variables—provided the memory model supplied the ordering guarantees the proof assumes.
JSR 133 rebuilt Java's thread semantics around a formal memory model in which happens-before relationships explain when writes must become visible across threads.
Leslie Lamport's 1974 bakery algorithm showed that mutual exclusion could be achieved using ordinary shared reads and writes, even under surprisingly weak assumptions about overlapping memory operations.
Compare-and-swap gave processors an atomic conditional update primitive powerful enough to build lock-free algorithms and, in theory, solve consensus for any number of threads.
Go brought lightweight goroutines and first-class channels into a mainstream systems language, translating a long CSP-inspired lineage into practical server software.
Edsger Dijkstra's semaphore abstraction gave concurrent programs explicit P and V operations for mutual exclusion, resource counting and process coordination.
Monitors moved mutual exclusion and condition synchronization into structured program modules, helping make shared-memory concurrency easier to reason about.
The actor model reframed concurrent computation around independent entities that receive messages, change behavior and send messages rather than sharing one call stack.