deallocated

Deallocated is the past participle of deallocate, meaning that a resource previously allocated has been released back to the system or pool. In computing, deallocation typically refers to memory management, where a program frees memory that is no longer needed. Deallocation can be manual, as in C and C++, where programmers call free or delete; or automatic, as in languages with garbage collection, where the runtime determines when objects are no longer reachable and reclaims their memory.

Manual deallocation requires careful matching of allocations and frees to avoid memory leaks or invalid frees. Improper deallocation can cause use-after-free, double-free, or dangling pointers. Many environments use smart pointers or ownership models to automate this process and reduce errors.

In garbage-collected languages, deallocation is generally non-deterministic: objects become eligible for collection when there are no references. Some runtimes use reference counting, tracing collectors, or generational schemes. For example, Python uses reference counting with a cyclic garbage collector; Java and C# employ tracing collectors. In systems programming, ownership-based languages like Rust provide deterministic deallocation through scope-based drop semantics.

Deallocation also applies to non-memory resources: file handles, sockets, graphics contexts, and other system resources. Proper deallocation avoids resource leaks and ensures resources are returned to their pools for reuse and future allocation.

In summary, deallocation is the process of releasing resources that were previously allocated, with approaches varying from manual frees to automatic garbage collection, and with implications for program safety and performance. See also memory management, memory leak, garbage collection, use-after-free, dangling pointer, RAII, and smart pointers.