Resource management is a crucial issue, especially in server software. One of the most valuable resources is memory, and memory management should be handled with extreme care. Memory management has been partially abstracted in Zend, and you should stick to this abstraction for obvious reasons: Due to the abstraction, Zend gets full control over all memory allocations. Zend is able to determine whether a block is in use, automatically freeing unused blocks and blocks with lost references, and thus prevent memory leaks. The functions to be used are described in the following table:
emalloc(), estrdup(), estrndup(), ecalloc(), and erealloc() allocate internal memory; efree() frees these previously allocated blocks. Memory handled by the e*() functions is considered local to the current process and is discarded as soon as the script executed by this process is terminated.
Zend also features a thread-safe resource manager to provide better native support for multithreaded Web servers. This requires you to allocate local structures for all of your global variables to allow concurrent threads to be run. Because the thread-safe mode of Zend was not finished back when this was written, it is not yet extensively covered here.