runtimesjekker

Runtimesjekker are tools and techniques to monitor and verify properties of a program while it runs, helping detect errors and enforce safety and correctness beyond static analysis. They operate by observing program state, inputs, and outputs and by checking invariants, bounds, or type constraints. They can be implemented at multiple levels: within the language runtime, through compiler or binary instrumentation, or by separate monitoring processes.

Common approaches include library-based checks that run as part of the program, compiler instrumentation that inserts checks into generated code, and external dynamic analysis tools that observe memory access, data races, or contract violations. Sanitizers such as AddressSanitizer and UBSan in C/C++ perform memory safety and undefined-behavior checks at runtime. Runtime verification frameworks monitor properties specified in a formal language or in annotations, evaluating them as the program executes. Assertions, contracts, and guards serve as explicit runtime checks that developers can enable or disable.

Use cases include catching null dereferences, out-of-bounds access, memory corruption, and invariant violations in data structures; debugging and testing; safety- and security-critical systems; and profiling for performance-cost trade-offs. Trade-offs include performance overhead, potential for false positives or negatives, and partial coverage of properties depending on the level of instrumentation and the quality of specifications.

Related concepts are runtime verification, dynamic analysis, and assertion-based programming. See also: memory safety, sanitizers, static analysis, instrumentation.