Editing C dynamic memory allocation (section)

==Overriding malloc==
Because  <code>malloc</code> and its relatives can have a strong impact on the performance of a program,<!--TODO: cite Bentley's Programming Pearls--> it is not uncommon to override the functions for a specific application by custom implementations that are optimized for application's allocation patterns. The C standard provides no way of doing this, but operating systems have found various ways to do this by exploiting dynamic linking. One way is to simply link in a different library to override the symbols. Another, employed by [[UNIX System V#SVR3|Unix System V.3]], is to make <code>malloc</code> and <code>free</code> function pointers that an application can reset to custom functions.<ref name="Levine_1999_CH9"/>

The most common form on POSIX-like systems is to set the environment variable LD_PRELOAD with the path of the allocator, so that the dynamic linker uses that version of malloc/calloc/free instead of the libc implementation.