memoryleak

Memory leak refers to a situation in which a computer program fails to release memory that is no longer needed, causing a gradual, unbounded growth of memory usage. Over time, this can reduce available memory for other processes and lead to slower performance, thrashing, or program crashes. Memory leaks can occur in any software environment but are especially problematic in long-running services and embedded systems.

Causes include failure to deallocate dynamically allocated memory, persistent references to objects after they are no longer needed, and holding resources such as file handles or database connections. In garbage-collected languages, leaks often arise from lingering references, closure captures, or caches that grow without bounds. In manual memory management languages, leaks typically result from mismatched allocations and deallocations or forgotten freed memory. Common patterns include cyclic references in reference-counted systems, unremoved event listeners, and caches that never evict entries.

Impact depends on the program and platform but can range from degraded performance to out-of-memory errors. In managed runtimes, leaks may not crash the process immediately but increase peak memory usage and pressure on the garbage collector.

Detection and diagnosis rely on profiling and heap analysis tools. Examples include Valgrind or AddressSanitizer for native code, JVM tools and Android leak detectors, .NET profilers, and browser developer tools that track allocations. System-level monitoring can help correlate leaks with aging memory usage.

Mitigation involves careful resource management: explicit deallocation in manual memory systems, smart pointers or RAII in C++, weak or cached references in managed runtimes, and timely eviction of cached data. Code reviews, testing, and long-running load tests are essential to identify leaks before deployment.