Memory Overflow (OOM) and memory leak (leak)

Memory Overflow (OOM): a situation in which running memory is larger than available memory. For example, the application of an integer space, the result is stored only a long to store the data memory leak (memory leak): The programmer forgot to release the memory used in the case of memory management is more common phenomenon

In the way that happens, memory leaks can be categorized into 4 categories:

1. Frequent memory leaks. The code that occurs in memory leaks is executed multiple times, causing a memory leak each time it is executed.

2. Accidental memory leaks. Code that occurs with a memory leak occurs only under certain circumstances or during operation. The occurrence and the incidental sex are opposite. For a given environment, the occasional may become a frequent occurrence. So test environments and test methods are critical to detecting memory leaks.

3. Disposable memory leaks. The code that occurs with a memory leak is only executed once, or because of an algorithmic flaw, there is always a piece of memory that leaks. For example, allocating memory in the class's constructor does not release the memory in the destructor, so a memory leak occurs only once.

4. An implicit memory leak. The program keeps allocating memory while it is running, but it does not release memory until the end. Strictly speaking, there is no memory leak, because the final program frees up all the requested memory. But for a server program that needs to run for days, weeks, or months, not releasing memory in time can also result in the eventual exhaustion of all of the system's memory. So, we call this kind of memory leak as an implicit memory leak.

From the user's point of view of using the program, the memory leak itself does not have any harm, as a general user, there is no sense of memory leaks. What is really harmful is the accumulation of memory leaks, which eventually consumes all the memory of the system. From this point of view, a one-time memory leak is harmless, because it does not accumulate, and the implicit memory leak is very harmful because it is more difficult to detect than the usual and sporadic memory leaks

Http://www.it165.net/os/html/201405/8168.html

Memory Overflow (OOM) and memory leak (leak)