Redis配置文件redis.conf详解学习笔记八

redis.conf:

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# Redis configuration file example

# Note on units: when memory size is needed, it is possible to specify

# it in the usual form of 1k 5GB 4M and so forth:

# 字节单位换算

# 1k => 1000 bytes

# 1kb => 1024 bytes

# 1m => 1000000 bytes

# 1mb => 1024*1024 bytes

# 1g => 1000000000 bytes

# 1gb => 1024*1024*1024 bytes

# 执行单元对大小写不敏感，1GB和1gb等价

# units are case insensitive so 1GB 1Gb 1gB are all the same.

################################## INCLUDES 包含 ###################################

# Include one or more other config files here.  This is useful if you

# have a standard template that goes to all Redis server but also need

# to customize a few per-server settings.  Include files can include

# other files, so use this wisely.

#

# Notice option "include" won't be rewritten by command "CONFIG REWRITE"

# from admin or Redis Sentinel. Since Redis always uses the last processed

# line as value of a configuration directive, you'd better put includes

# at the beginning of this file to avoid overwriting config change at runtime.

#

# If instead you are interested in using includes to override configuration

# options, it is better to use include as the last line.

# 包含其它redis的配置文件模块进来

# include /path/to/local.conf

# include /path/to/other.conf

################################ GENERAL  常用 #####################################

#默认情况下， redis 不是在后台运行的，如果需要在后台运行，把该项的值更改为 yes

# By default Redis does not run as a daemon. Use 'yes' if you need it.

# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.

daemonize no

#如果以后台进程运行的话，就需要指定pid，你可以在此自定义redis.pid文件的位置。

# When running daemonized, Redis writes a pid file in /var/run/redis.pid by

# default. You can specify a custom pid file location here.

pidfile /var/run/redis.pid

#接受连接的端口号，如果端口是0则redis将不会监听TCP socket连接

# Accept connections on the specified port, default is 6379.

# If port 0 is specified Redis will not listen on a TCP socket.

port 6379

# TCP listen() backlog.

#

# In high requests-per-second environments you need an high backlog in order

# to avoid slow clients connections issues. Note that the Linux kernel

# will silently truncate it to the value of /proc/sys/net/core/somaxconn so

# make sure to raise both the value of somaxconn and tcp_max_syn_backlog

# in order to get the desired effect.

 

# By default Redis listens for connections from all the network interfaces

# available on the server. It is possible to listen to just one or multiple

# interfaces using the "bind" configuration directive, followed by one or

# more IP addresses.

#

# Examples:

#

# bind 192.168.1.100 10.0.0.1

# bind 127.0.0.1

# Specify the path for the Unix socket that will be used to listen for

# incoming connections. There is no default, so Redis will not listen

# on a unix socket when not specified.

#

# unixsocket /tmp/redis.sock

# unixsocketperm 755

# Close the connection after a client is idle for N seconds (0 to disable)

#连接超时时间，单位秒。

timeout 0

# tcp 心跳包

# TCP keepalive.

#

# If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence

# of communication. This is useful for two reasons:

#

# 1) Detect dead peers.

# 2) Take the connection alive from the point of view of network

#    equipment in the middle.

#

# On Linux, the specified value (in seconds) is the period used to send ACKs.

# Note that to close the connection the double of the time is needed.

# On other kernels the period depends on the kernel configuration.

# 

# A reasonable value for this option is 60 seconds.

tcp-keepalive 0

#定义日志级别

# Specify the server verbosity level.

# This can be one of:

# debug (a lot of information, useful for development/testing)

# verbose (many rarely useful info, but not a mess like the debug level)

# notice (moderately verbose, what you want in production probably)

# warning (only very important / critical messages are logged)

loglevel notice

#指定日志文件的位置

# Specify the log file name. Also the empty string can be used to force

# Redis to log on the standard output. Note that if you use standard

# output for logging but daemonize, logs will be sent to /dev/null

logfile ""

# 要想把日志记录到系统日志，就把它改成 yes

# To enable logging to the system logger, just set 'syslog-enabled' to yes,

# and optionally update the other syslog parameters to suit your needs.

# syslog-enabled no

# 设置 syslog 的 identity

# Specify the syslog identity.

# syslog-ident redis

# 设置 syslog 的 facility，必须是 USER 或者是 LOCAL0-LOCAL7 之间的值

# Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.

# syslog-facility local0

# 设置数据库的数目

# Set the number of databases. The default database is DB 0, you can select

# a different one on a per-connection basis using SELECT <dbid> where

# dbid is a number between 0 and 'databases'-1

databases 16

################################ SNAPSHOTTING  快照 ################################

# 存 DB 到磁盘

# Save the DB on disk:

#   900 秒后如果至少有 1 个 key 的值变化，则保存

#   300 秒后如果至少有 10 个 key 的值变化，则保存

#   60 秒后如果至少有 10000 个 key 的值变化，则保存

#   注意：你可以注释掉所有的 save 行来停用保存功能。

#   也可以直接一个空字符串来实现停用

#   save <seconds> <changes>

#

#   Will save the DB if both the given number of seconds and the given

#   number of write operations against the DB occurred.

#

#   In the example below the behaviour will be to save:

#   after 900 sec (15 min) if at least 1 key changed

#   after 300 sec (5 min) if at least 10 keys changed

#   after 60 sec if at least 10000 keys changed

#

#   Note: you can disable saving at all commenting all the "save" lines.

#

#   It is also possible to remove all the previously configured save

#   points by adding a save directive with a single empty string argument

#   like in the following example:

#

#   save ""

save 900 1

save 300 10

save 60 10000

# 默认情况下，如果 redis 最后一次的后台保存失败，redis 将停止接受写操作，

# 这样以一种强硬的方式让用户知道数据不能正确的持久化到磁盘，

# 否则就会没人注意到灾难的发生。

# 如果后台保存进程重新启动工作了，redis 也将自动的允许写操作。

# By default Redis will stop accepting writes if RDB snapshots are enabled

# (at least one save point) and the latest background save failed.

# This will make the user aware (in a hard way) that data is not persisting

# on disk properly, otherwise chances are that no one will notice and some

# disaster will happen.

#

# If the background saving process will start working again Redis will

# automatically allow writes again.

#

# However if you have setup your proper monitoring of the Redis server

# and persistence, you may want to disable this feature so that Redis will

# continue to work as usual even if there are problems with disk,

# permissions, and so forth.

stop-writes-on-bgsave-error yes

# 是否在 dump .rdb 数据库的时候使用 LZF 压缩字符串

# Compress string objects using LZF when dump .rdb databases?

# For default that's set to 'yes' as it's almost always a win.

# If you want to save some CPU in the saving child set it to 'no' but

# the dataset will likely be bigger if you have compressible values or keys.

rdbcompression yes

# 是否校验rdb文件

# Since version 5 of RDB a CRC64 checksum is placed at the end of the file.

# This makes the format more resistant to corruption but there is a performance

# hit to pay (around 10%) when saving and loading RDB files, so you can disable it

# for maximum performances.

#

# RDB files created with checksum disabled have a checksum of zero that will

# tell the loading code to skip the check.

rdbchecksum yes

# 设置 dump 的文件位置

# The filename where to dump the DB

dbfilename dump.rdb

# 工作目录

# The working directory.

#

# The DB will be written inside this directory, with the filename specified

# above using the 'dbfilename' configuration directive.

# 

# The Append Only File will also be created inside this directory.

# 

# Note that you must specify a directory here, not a file name.

dir ./

################################# REPLICATION 主从复制#################################

# 主从复制。使用 slaveof 来让一个 redis 实例成为另一个reids 实例的副本。

# 注意这个只需要在 slave 上配置。

# Master-Slave replication. Use slaveof to make a Redis instance a copy of

# another Redis server. Note that the configuration is local to the slave

# so for example it is possible to configure the slave to save the DB with a

# different interval, or to listen to another port, and so on.

#

# slaveof <masterip> <masterport>

# If the master is password protected (using the "requirepass" configuration

# directive below) it is possible to tell the slave to authenticate before

# starting the replication synchronization process, otherwise the master will

# refuse the slave request.

#

# 如果 master 需要密码认证，就在这里设置

# masterauth <master-password>

# 当一个 slave 与 master 失去联系，或者复制正在进行的时候，

# slave 可能会有两种表现：

#

# 1) 如果为 yes ，slave 仍然会应答客户端请求，但返回的数据可能是过时，

#    或者数据可能是空的在第一次同步的时候

#

# 2) 如果为 no ，在你执行除了 info he salveof 之外的其他命令时，

#    slave 都将返回一个 "SYNC with master in progress" 的错误，

# When a slave loses its connection with the master, or when the replication

# is still in progress, the slave can act in two different ways:

#

# 1) if slave-serve-stale-data is set to 'yes' (the default) the slave will

#    still reply to client requests, possibly with out of date data, or the

#    data set may just be empty if this is the first synchronization.

#

# 2) if slave-serve-stale-data is set to 'no' the slave will reply with

#    an error "SYNC with master in progress" to all the kind of commands

#    but to INFO and SLAVEOF.

#

slave-serve-stale-data yes

# 你可以配置一个 slave 实体是否接受写入操作。

# 通过写入操作来存储一些短暂的数据对于一个 slave 实例来说可能是有用的，

# 因为相对从 master 重新同步数而言，据数据写入到 slave 会更容易被删除。

# 但是如果客户端因为一个错误的配置写入，也可能会导致一些问题。

#

# 从 redis 2.6 版起，默认 slaves 都是只读的。

# You can configure a slave instance to accept writes or not. Writing against

# a slave instance may be useful to store some ephemeral data (because data

# written on a slave will be easily deleted after resync with the master) but

# may also cause problems if clients are writing to it because of a

# misconfiguration.

#

# Since Redis 2.6 by default slaves are read-only.

#

# Note: read only slaves are not designed to be exposed to untrusted clients

# on the internet. It's just a protection layer against misuse of the instance.

# Still a read only slave exports by default all the administrative commands

# such as CONFIG, DEBUG, and so forth. To a limited extent you can improve

# security of read only slaves using 'rename-command' to shadow all the

# administrative / dangerous commands.

slave-read-only yes

# Slaves 在一个预定义的时间间隔内发送 ping 命令到 server 。

# 你可以改变这个时间间隔。默认为 10 秒。

# Slaves send PINGs to server in a predefined interval. It's possible to change

# this interval with the repl_ping_slave_period option. The default value is 10

# seconds.

#

# repl-ping-slave-period 10

# The following option sets the replication timeout for:

# 设置主从复制过期时间

# 1) Bulk transfer I/O during SYNC, from the point of view of slave.

# 2) Master timeout from the point of view of slaves (data, pings).

# 3) Slave timeout from the point of view of masters (REPLCONF ACK pings).

#

# It is important to make sure that this value is greater than the value

# specified for repl-ping-slave-period otherwise a timeout will be detected

# every time there is low traffic between the master and the slave.

#

# repl-timeout 60

# Disable TCP_NODELAY on the slave socket after SYNC?

#

# If you select "yes" Redis will use a smaller number of TCP packets and

# less bandwidth to send data to slaves. But this can add a delay for

# the data to appear on the slave side, up to 40 milliseconds with

# Linux kernels using a default configuration.

#

# If you select "no" the delay for data to appear on the slave side will

# be reduced but more bandwidth will be used for replication.

#

# By default we optimize for low latency, but in very high traffic conditions

# or when the master and slaves are many hops away, turning this to "yes" may

# be a good idea.

repl-disable-tcp-nodelay no

# Set the replication backlog size. The backlog is a buffer that accumulates

# slave data when slaves are disconnected for some time, so that when a slave

# wants to reconnect again, often a full resync is not needed, but a partial

# resync is enough, just passing the portion of data the slave missed while

# disconnected.

#

# The biggest the replication backlog, the longer the time the slave can be

# disconnected and later be able to perform a partial resynchronization.

#

# The backlog is only allocated once there is at least a slave connected.

#

# repl-backlog-size 1mb

# After a master has no longer connected slaves for some time, the backlog

# will be freed. The following option configures the amount of seconds that

# need to elapse, starting from the time the last slave disconnected, for

# the backlog buffer to be freed.

#

# A value of 0 means to never release the backlog.

#

# repl-backlog-ttl 3600

# 当 master 不能正常工作的时候，Redis Sentinel 会从 slaves 中选出一个新的 master，

# 这个值越小，就越会被优先选中，但是如果是 0 ， 那是意味着这个 slave 不可能被选中。

#

# 默认优先级为 100。

# The slave priority is an integer number published by Redis in the INFO output.

# It is used by Redis Sentinel in order to select a slave to promote into a

# master if the master is no longer working correctly.

#

# A slave with a low priority number is considered better for promotion, so

# for instance if there are three slaves with priority 10, 100, 25 Sentinel will

# pick the one with priority 10, that is the lowest.

#

# However a special priority of 0 marks the slave as not able to perform the

# role of master, so a slave with priority of 0 will never be selected by

# Redis Sentinel for promotion.

#

# By default the priority is 100.

slave-priority 100

# It is possible for a master to stop accepting writes if there are less than

# N slaves connected, having a lag less or equal than M seconds.

#

# The N slaves need to be in "online" state.

#

# The lag in seconds, that must be <= the specified value, is calculated from

# the last ping received from the slave, that is usually sent every second.

#

# This option does not GUARANTEES that N replicas will accept the write, but

# will limit the window of exposure for lost writes in case not enough slaves

# are available, to the specified number of seconds.

#

# For example to require at least 3 slaves with a lag <= 10 seconds use:

#

# min-slaves-to-write 3

# min-slaves-max-lag 10

#

# Setting one or the other to 0 disables the feature.

#

# By default min-slaves-to-write is set to 0 (feature disabled) and

# min-slaves-max-lag is set to 10.

################################## SECURITY 安全###################################

# Require clients to issue AUTH <PASSWORD> before processing any other

# commands.  This might be useful in environments in which you do not trust

# others with access to the host running redis-server.

#

# This should stay commented out for backward compatibility and because most

# people do not need auth (e.g. they run their own servers).

# 

# Warning: since Redis is pretty fast an outside user can try up to

# 150k passwords per second against a good box. This means that you should

# use a very strong password otherwise it will be very easy to break.

# 设置认证密码abc

# requirepass foobared

  requirepass abc

# Command renaming.

#

# It is possible to change the name of dangerous commands in a shared

# environment. For instance the CONFIG command may be renamed into something

# hard to guess so that it will still be available for internal-use tools

# but not available for general clients.

#

# Example:

#

# rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52

#

# It is also possible to completely kill a command by renaming it into

# an empty string:

#

# rename-command CONFIG ""

#

# Please note that changing the name of commands that are logged into the

# AOF file or transmitted to slaves may cause problems.

################################### LIMITS 限制 ####################################

# Set the max number of connected clients at the same time. By default

# this limit is set to 10000 clients, however if the Redis server is not

# able to configure the process file limit to allow for the specified limit

# the max number of allowed clients is set to the current file limit

# minus 32 (as Redis reserves a few file descriptors for internal uses).

#

# Once the limit is reached Redis will close all the new connections sending

# an error 'max number of clients reached'.

# 连接服务器的客户端的最大数量,达到最大限制时，redis关闭所有连接，并返回错误信息

# maxclients 10000

# Don't use more memory than the specified amount of bytes.

# When the memory limit is reached Redis will try to remove keys

# according to the eviction policy selected (see maxmemory-policy).

#

# If Redis can't remove keys according to the policy, or if the policy is

# set to 'noeviction', Redis will start to reply with errors to commands

# that would use more memory, like SET, LPUSH, and so on, and will continue

# to reply to read-only commands like GET.

#

# This option is usually useful when using Redis as an LRU cache, or to set

# a hard memory limit for an instance (using the 'noeviction' policy).

#

# WARNING: If you have slaves attached to an instance with maxmemory on,

# the size of the output buffers needed to feed the slaves are subtracted

# from the used memory count, so that network problems / resyncs will

# not trigger a loop where keys are evicted, and in turn the output

# buffer of slaves is full with DELs of keys evicted triggering the deletion

# of more keys, and so forth until the database is completely emptied.

#

# In short... if you have slaves attached it is suggested that you set a lower

# limit for maxmemory so that there is some free RAM on the system for slave

# output buffers (but this is not needed if the policy is 'noeviction').

# 最大使用内存

# maxmemory <bytes>

#最大内存的选择策略

# MAXMEMORY POLICY: how Redis will select what to remove when maxmemory

# is reached. You can select among five behaviors:

# 

# volatile-lru -> remove the key with an expire set using an LRU algorithm

# volatile-lru -> 使用 LRU 算法移除包含过期设置的 key 。

# allkeys-lru -> remove any key accordingly to the LRU algorithm

# allkeys-lru -> 根据 LRU 算法移除所有的 key 。

# volatile-random -> remove a random key with an expire set

# allkeys-random -> remove a random key, any key

# volatile-ttl -> remove the key with the nearest expire time (minor TTL)

# noeviction -> don't expire at all, just return an error on write operations

# noeviction -> 不让任何 key 过期，只是给写入操作返回一个错误

#

# volatile-lru -> remove the key with an expire set using an LRU algorithm

# allkeys-lru -> remove any key accordingly to the LRU algorithm

# volatile-random -> remove a random key with an expire set

# allkeys-random -> remove a random key, any key

# volatile-ttl -> remove the key with the nearest expire time (minor TTL)

# noeviction -> don't expire at all, just return an error on write operations

# 

# Note: with any of the above policies, Redis will return an error on write

#       operations, when there are not suitable keys for eviction.

#

#       At the date of writing this commands are: set setnx setex append

#       incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd

#       sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby

#       zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby

#       getset mset msetnx exec sort

#

# The default is:

# 默认最大内存选择策略

# maxmemory-policy volatile-lru

# LRU and minimal TTL algorithms are not precise algorithms but approximated

# algorithms (in order to save memory), so you can select as well the sample

# size to check. For instance for default Redis will check three keys and

# pick the one that was used less recently, you can change the sample size

# using the following configuration directive.

#

# maxmemory-samples 3

############################## APPEND ONLY MODE aof备份模式 ###############################

# By default Redis asynchronously dumps the dataset on disk. This mode is

# good enough in many applications, but an issue with the Redis process or

# a power outage may result into a few minutes of writes lost (depending on

# the configured save points).

#

# The Append Only File is an alternative persistence mode that provides

# much better durability. For instance using the default data fsync policy

# (see later in the config file) Redis can lose just one second of writes in a

# dramatic event like a server power outage, or a single write if something

# wrong with the Redis process itself happens, but the operating system is

# still running correctly.

#

# AOF and RDB persistence can be enabled at the same time without problems.

# If the AOF is enabled on startup Redis will load the AOF, that is the file

# with the better durability guarantees.

#

# Please check http://redis.io/topics/persistence for more information.

#默认关闭append only mode 

appendonly no

# The name of the append only file (default: "appendonly.aof")

appendfilename "appendonly.aof"

# The fsync() call tells the Operating System to actually write data on disk

# instead to wait for more data in the output buffer. Some OS will really flush 

# data on disk, some other OS will just try to do it ASAP.

#

# Redis 支持三种同步 AOF 文件的策略

# Redis supports three different modes:

#

# no: don't fsync, just let the OS flush the data when it wants. Faster.

# always: fsync after every write to the append only log . Slow, Safest.

# everysec: fsync only one time every second. Compromise.

#

# The default is "everysec", as that's usually the right compromise between

# speed and data safety. It's up to you to understand if you can relax this to

# "no" that will let the operating system flush the output buffer when

# it wants, for better performances (but if you can live with the idea of

# some data loss consider the default persistence mode that's snapshotting),

# or on the contrary, use "always" that's very slow but a bit safer than

# everysec.

#

# More details please check the following article:

# http://antirez.com/post/redis-persistence-demystified.html

#

# If unsure, use "everysec".

# always: always 表示每次有写操作都进行同步 . Slow, Safest.

# appendfsync always

# everysec:  表示对写操作进行累积，每秒同步一次 . Compromise.默认.

appendfsync everysec

# no:  不进行同步，系统去操作  . Faster.

# appendfsync no

# When the AOF fsync policy is set to always or everysec, and a background

# saving process (a background save or AOF log background rewriting) is

# performing a lot of I/O against the disk, in some Linux configurations

# Redis may block too long on the fsync() call. Note that there is no fix for

# this currently, as even performing fsync in a different thread will block

# our synchronous write(2) call.

#

# In order to mitigate this problem it's possible to use the following option

# that will prevent fsync() from being called in the main process while a

# BGSAVE or BGREWRITEAOF is in progress.

#

# This means that while another child is saving, the durability of Redis is

# the same as "appendfsync none". In practical terms, this means that it is

# possible to lose up to 30 seconds of log in the worst scenario (with the

# default Linux settings).

# 

# 当AOF fsync策略被设置为always或者everysec并且后台保存进程（saving process)正在执行大量I/O操作时

# Redis可能会在fsync()调用上阻塞过长时间

# If you have latency problems turn this to "yes". Otherwise leave it as

# "no" that is the safest pick from the point of view of durability.

no-appendfsync-on-rewrite no

# Automatic rewrite of the append only file.

# Redis is able to automatically rewrite the log file implicitly calling

# BGREWRITEAOF when the AOF log size grows by the specified percentage.

# 

# This is how it works: Redis remembers the size of the AOF file after the

# latest rewrite (if no rewrite has happened since the restart, the size of

# the AOF at startup is used).

#

# This base size is compared to the current size. If the current size is

# bigger than the specified percentage, the rewrite is triggered. Also

# you need to specify a minimal size for the AOF file to be rewritten, this

# is useful to avoid rewriting the AOF file even if the percentage increase

# is reached but it is still pretty small.

#

# Specify a percentage of zero in order to disable the automatic AOF

# rewrite feature.

# auto-aof-rewrite-percentage 设置为 0 可以关闭AOF重写功能

auto-aof-rewrite-percentage 100

auto-aof-rewrite-min-size 64mb

################################ LUA SCRIPTING  lua脚本 ###############################

# Max execution time of a Lua script in milliseconds.

#

# If the maximum execution time is reached Redis will log that a script is

# still in execution after the maximum allowed time and will start to

# reply to queries with an error.

#

# When a long running script exceed the maximum execution time only the

# SCRIPT KILL and SHUTDOWN NOSAVE commands are available. The first can be

# used to stop a script that did not yet called write commands. The second

# is the only way to shut down the server in the case a write commands was

# already issue by the script but the user don't want to wait for the natural

# termination of the script.

# lua脚本最长执行时间为 5000 毫秒（ 5 秒），如果为 0 或负数表示无限执行时间。

# Set it to 0 or a negative value for unlimited execution without warnings.

lua-time-limit 5000

################################## 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.

# 负数则关闭slow log，0则会导致每个命令都被记录

slowlog-log-slower-than 10000

# 不设置会消耗过多内存，所以还是要设置一下。可以使用SLOWLOG RESET命令来回收slow log使用的内存

# 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

############################# Event notification 事件通知 ##############################

# Redis can notify Pub/Sub clients about events happening in the key space.

# This feature is documented at http://redis.io/topics/keyspace-events

# 

# For instance if keyspace events notification is enabled, and a client

# performs a DEL operation on key "foo" stored in the Database 0, two

# messages will be published via Pub/Sub:

#

# PUBLISH __keyspace@0__:foo del

# PUBLISH __keyevent@0__:del foo

#

# It is possible to select the events that Redis will notify among a set

# of classes. Every class is identified by a single character:

#

#  K     Keyspace events, published with __keyspace@<db>__ prefix.

#  E     Keyevent events, published with __keyevent@<db>__ prefix.

#  g     Generic commands (non-type specific) like DEL, EXPIRE, RENAME, ...

#  $     String commands

#  l     List commands

#  s     Set commands

#  h     Hash commands

#  z     Sorted set commands

#  x     Expired events (events generated every time a key expires)

#  e     Evicted events (events generated when a key is evicted for maxmemory)

#  A     Alias for g$lshzxe, so that the "AKE" string means all the events.

#

#  The "notify-keyspace-events" takes as argument a string that is composed

#  by zero or multiple characters. The empty string means that notifications

#  are disabled at all.

#

#  Example: to enable list and generic events, from the point of view of the

#           event name, use:

#

#  notify-keyspace-events Elg

#

#  Example 2: to get the stream of the expired keys subscribing to channel

#             name __keyevent@0__:expired use:

#

#  notify-keyspace-events Ex

#

#  By default all notifications are disabled because most users don't need

#  this feature and the feature has some overhead. Note that if you don't

#  specify at least one of K or E, no events will be delivered.

notify-keyspace-events ""

############################### ADVANCED CONFIG 高级配置 ###############################

# Hashes are encoded using a memory efficient data structure when they have a

# small number of entries, and the biggest entry does not exceed a given

# threshold. These thresholds can be configured using the following directives.

hash-max-ziplist-entries 512

hash-max-ziplist-value 64

# Similarly to hashes, small lists are also encoded in a special way in order

# to save a lot of space. The special representation is only used when

# you are under the following limits:

list-max-ziplist-entries 512

list-max-ziplist-value 64

# Sets have a special encoding in just one case: when a set is composed

# of just strings that happens to be integers in radix 10 in the range

# of 64 bit signed integers.

# The following configuration setting sets the limit in the size of the

# set in order to use this special memory saving encoding.

set-max-intset-entries 512

# Similarly to hashes and lists, sorted sets are also specially encoded in

# order to save a lot of space. This encoding is only used when the length and

# elements of a sorted set are below the following limits:

zset-max-ziplist-entries 128

zset-max-ziplist-value 64

# HyperLogLog sparse representation bytes limit. The limit includes the

# 16 bytes header. When an HyperLogLog using the sparse representation crosses

# this limit, it is converted into the dense representation.

#

# A value greater than 16000 is totally useless, since at that point the

# dense representation is more memory efficient.

# 

# The suggested value is ~ 3000 in order to have the benefits of

# the space efficient encoding without slowing down too much PFADD,

# which is O(N) with the sparse encoding. The value can be raised to

# ~ 10000 when CPU is not a concern, but space is, and the data set is

# composed of many HyperLogLogs with cardinality in the 0 - 15000 range.

hll-sparse-max-bytes 3000

# Active rehashing uses 1 millisecond every 100 milliseconds of CPU time in

# order to help rehashing the main Redis hash table (the one mapping top-level

# keys to values). The hash table implementation Redis uses (see dict.c)

# performs a lazy rehashing: the more operation you run into a hash table

# that is rehashing, the more rehashing "steps" are performed, so if the

# server is idle the rehashing is never complete and some more memory is used

# by the hash table.

# 

# The default is to use this millisecond 10 times every second in order to

# active rehashing the main dictionaries, freeing memory when possible.

#

# If unsure:

# use "activerehashing no" if you have hard latency requirements and it is

# not a good thing in your environment that Redis can reply form time to time

# to queries with 2 milliseconds delay.

#

# use "activerehashing yes" if you don't have such hard requirements but

# want to free memory asap when possible.

#  当你的使用场景中，有非常严格的实时性需要，不能够接受 Redis 时不时的对请求有 2 毫秒的延迟的话，把这项配置为 no 。

#  如果没有这么严格的实时性要求，可以设置为 yes ，以便能够尽可能快的释放内存

activerehashing yes

# The client output buffer limits can be used to force disconnection of clients

# that are not reading data from the server fast enough for some reason (a

# common reason is that a Pub/Sub client can't consume messages as fast as the

# publisher can produce them).

#

# The limit can be set differently for the three different classes of clients:

#  可以三种不同客户端的方式进行设置：

# normal ->  正常客户端

# slave  -> slave 和 MONITOR 客户端

# pubsub ->  至少订阅了一个 pubsub channel 或 pattern 的客户端

# normal -> normal clients including MONITOR clients

# slave  -> slave clients

# pubsub -> clients subscribed to at least one pubsub channel or pattern

#

# The syntax of every client-output-buffer-limit directive is the following:

#

# client-output-buffer-limit <class> <hard limit> <soft limit> <soft seconds>

#

# A client is immediately disconnected once the hard limit is reached, or if

# the soft limit is reached and remains reached for the specified number of

# seconds (continuously).

# So for instance if the hard limit is 32 megabytes and the soft limit is

# 16 megabytes / 10 seconds, the client will get disconnected immediately

# if the size of the output buffers reach 32 megabytes, but will also get

# disconnected if the client reaches 16 megabytes and continuously overcomes

# the limit for 10 seconds.

#

# By default normal clients are not limited because they don't receive data

# without asking (in a push way), but just after a request, so only

# asynchronous clients may create a scenario where data is requested faster

# than it can read.

#

# Instead there is a default limit for pubsub and slave clients, since

# subscribers and slaves receive data in a push fashion.

#

# Both the hard or the soft limit can be disabled by setting them to zero.

client-output-buffer-limit normal 0 0 0

client-output-buffer-limit slave 256mb 64mb 60

client-output-buffer-limit pubsub 32mb 8mb 60

# Redis calls an internal function to perform many background tasks, like

# closing connections of clients in timeout, purging expired keys that are

# never requested, and so forth.

#

# Not all tasks are performed with the same frequency, but Redis checks for

# tasks to perform accordingly to the specified "hz" value.

#

# By default "hz" is set to 10. Raising the value will use more CPU when

# Redis is idle, but at the same time will make Redis more responsive when

# there are many keys expiring at the same time, and timeouts may be

# handled with more precision.

#

# The range is between 1 and 500, however a value over 100 is usually not

# a good idea. Most users should use the default of 10 and raise this up to

# 100 only in environments where very low latency is required.

hz 10

# When a child rewrites the AOF file, if the following option is enabled

# the file will be fsync-ed every 32 MB of data generated. This is useful

# in order to commit the file to the disk more incrementally and avoid

# big latency spikes.

#  当一个子节点重写 AOF 文件时，如果启用下面的选项，则文件每生成 32M 数据进行同步。

aof-rewrite-incremental-fsync yes

aof-rewrite-incremental-fsync yes

====================================================================================