Redis is an open-source, networked, in-memory, key-value data store with optional durability. It is written in ANSI C. The development of Redis has been sponsored by Pivotal since May 2013; before that, it was sponsored by VMware. According to the monthly ranking by DB-Engines.com, Redis is the most popular key-value store. The name Redis means REmote DIctionary Server.
There is a replacement for the UNIX fork() API that simulates the copy-on-write behavior using a memory mapped file on 2.8. Version 3.0 is using a similar behavior but dropped the memory mapped file in favor of the system paging file.
In 3.0 we switch the default memory allocator from dlmalloc to jemalloc that is supposed to do a better job at managing the heap fragmentation.
Because Redis makes some assumptions about the values of file descriptors, we have built a virtual file descriptor mapping layer.