# #ddev-generated ################################ THREADED I/O ################################# # Redis is mostly single threaded, however there are certain threaded # operations such as UNLINK, slow I/O accesses and other things that are # performed on side threads. # # Now it is also possible to handle Redis clients socket reads and writes # in different I/O threads. Since especially writing is so slow, normally # Redis users use pipelining in order to speed up the Redis performances per # core, and spawn multiple instances in order to scale more. Using I/O # threads it is possible to easily speedup two times Redis without resorting # to pipelining nor sharding of the instance. # # By default threading is disabled, we suggest enabling it only in machines # that have at least 4 or more cores, leaving at least one spare core. # Using more than 8 threads is unlikely to help much. We also recommend using # threaded I/O only if you actually have performance problems, with Redis # instances being able to use a quite big percentage of CPU time, otherwise # there is no point in using this feature. # # So for instance if you have a four cores boxes, try to use 2 or 3 I/O # threads, if you have a 8 cores, try to use 6 threads. In order to # enable I/O threads use the following configuration directive: # io-threads 1 # # Setting io-threads to 1 will just use the main thread as usual. # When I/O threads are enabled, we only use threads for writes, that is # to thread the write(2) syscall and transfer the client buffers to the # socket. However it is also possible to enable threading of reads and # protocol parsing using the following configuration directive, by setting # it to yes: # io-threads-do-reads no # # Usually threading reads doesn't help much. # # NOTE 1: This configuration directive cannot be changed at runtime via # CONFIG SET. Aso this feature currently does not work when SSL is # enabled. # # NOTE 2: If you want to test the Redis speedup using redis-benchmark, make # sure you also run the benchmark itself in threaded mode, using the # --threads option to match the number of Redis threads, otherwise you'll not # be able to notice the improvements. ############################ KERNEL OOM CONTROL ############################## # On Linux, it is possible to hint the kernel OOM killer on what processes # should be killed first when out of memory. # # Enabling this feature makes Redis actively control the oom_score_adj value # for all its processes, depending on their role. The default scores will # attempt to have background child processes killed before all others, and # replicas killed before masters. oom-score-adj no # When oom-score-adj is used, this directive controls the specific values used # for master, replica and background child processes. Values range -1000 to # 1000 (higher means more likely to be killed). # # Unprivileged processes (not root, and without CAP_SYS_RESOURCE capabilities) # can freely increase their value, but not decrease it below its initial # settings. # # Values are used relative to the initial value of oom_score_adj when the server # starts. Because typically the initial value is 0, they will often match the # absolute values. oom-score-adj-values 0 200 800 ################################## SLOW LOG ################################### # The Redis Slow Log is a system to log queries that exceeded a specified # execution time. The execution time does not include the I/O operations # like talking with the client, sending the reply and so forth, # but just the time needed to actually execute the command (this is the only # stage of command execution where the thread is blocked and can not serve # other requests in the meantime). # # You can configure the slow log with two parameters: one tells Redis # what is the execution time, in microseconds, to exceed in order for the # command to get logged, and the other parameter is the length of the # slow log. When a new command is logged the oldest one is removed from the # queue of logged commands. # The following time is expressed in microseconds, so 1000000 is equivalent # to one second. Note that a negative number disables the slow log, while # a value of zero forces the logging of every command. slowlog-log-slower-than 10000 # There is no limit to this length. Just be aware that it will consume memory. # You can reclaim memory used by the slow log with SLOWLOG RESET. slowlog-max-len 128