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Redis uses a function called serverCron() that is very similar to the timer interrupt of an operating system. This function is used to handle a number of asynchronous things, like active expired keys collection, clients timeouts, update of statistics, things related to the cluster and replication, triggering of BGSAVE and AOF rewrite process, and so forth. In the past the timer was called 1 time per second. At some point it was raised to 10 times per second, but it still was fixed and could not be changed even at compile time, because different functions called from serverCron() assumed a given fixed frequency. This commmit makes the frequency configurable, so that it is simpler to pick a good tradeoff between overhead of this function (that is usually very small) and the responsiveness of Redis during a few critical circumstances where a lot of work is done inside the timer. An example of such a critical condition is mass-expire of a lot of keys in the same second. Up to a given percentage of CPU time is used to perform expired keys collection per expire cylce. Now changing the REDIS_HZ macro it is possible to do less work but more times per second in order to block the server for less time. If this patch will work well in our tests it will enter Redis 2.6-final.
Where to find complete Redis documentation? ------------------------------------------- This README is just a fast "quick start" document. You can find more detailed documentation at http://redis.io Building Redis -------------- Redis can be compiled and used on Linux, OSX, OpenBSD, NetBSD, FreeBSD. We support big endian and little endian architectures. It may compile on Solaris derived systems (for instance SmartOS) but our support for this platform is "best effort" and Redis is not guaranteed to work as well as in Linux, OSX, and *BSD there. It is as simple as: % make You can run a 32 bit Redis binary using: % make 32bit After building Redis is a good idea to test it, using: % make test NOTE: if after building Redis with a 32 bit target you need to rebuild it with a 64 bit target you need to perform a "make clean" in the root directory of the Redis distribution. Allocator --------- Selecting a non-default memory allocator when building Redis is done by setting the `MALLOC` environment variable. Redis is compiled and linked against libc malloc by default, with the exception of jemalloc being the default on Linux systems. This default was picked because jemalloc has proven to have fewer fragmentation problems than libc malloc. To force compiling against libc malloc, use: % make MALLOC=libc To compile against jemalloc on Mac OS X systems, use: % make MALLOC=jemalloc Verbose build ------------- Redis will build with a user friendly colorized output by default. If you want to see a more verbose output use the following: % make V=1 Running Redis ------------- To run Redis with the default configuration just type: % cd src % ./redis-server If you want to provide your redis.conf, you have to run it using an additional parameter (the path of the configuration file): % cd src % ./redis-server /path/to/redis.conf It is possible to alter the Redis configuration passing parameters directly as options using the command line. Examples: % ./redis-server --port 9999 --slaveof 127.0.0.1 6379 % ./redis-server /etc/redis/6379.conf --loglevel debug All the options in redis.conf are also supported as options using the command line, with exactly the same name. Playing with Redis ------------------ You can use redis-cli to play with Redis. Start a redis-server instance, then in another terminal try the following: % cd src % ./redis-cli redis> ping PONG redis> set foo bar OK redis> get foo "bar" redis> incr mycounter (integer) 1 redis> incr mycounter (integer) 2 redis> You can find the list of all the available commands here: http://redis.io/commands Installing Redis ----------------- In order to install Redis binaries into /usr/local/bin just use: % make install You can use "make PREFIX=/some/other/directory install" if you wish to use a different destination. Make install will just install binaries in your system, but will not configure init scripts and configuration files in the appropriate place. This is not needed if you want just to play a bit with Redis, but if you are installing it the proper way for a production system, we have a script doing this for Ubuntu and Debian systems: % cd utils % ./install_server The script will ask you a few questions and will setup everything you need to run Redis properly as a background daemon that will start again on system reboots. You'll be able to stop and start Redis using the script named /etc/init.d/redis_<portnumber>, for instance /etc/init.d/redis_6379. Enjoy!
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