redis配置详情
- # 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:
- # 内存大小的配置,下面是内存大小配置的转换方式
- #
- # 1k => 1000 bytes
- # 1kb => 1024 bytes
- # 1m => 1000000 bytes
- # 1mb => 1024*1024 bytes
- # 1g => 1000000000 bytes
- # 1gb => 1024*1024*1024 bytes
- #
- # units are case insensitive so 1GB 1Gb 1gB are all the same.
- # 内存大小的配置,不区分大小写
- ################################## INCLUDES ###################################
- # 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.
- #
- # include /path/to/local.conf
- # include /path/to/other.conf
- # 当配置多个redis时,可能大部分配置一样,而对于不同的redis,只有少部分配置需要定制
- # 就可以配置一个公共的模板配置。
- # 对于具体的reids,只需设置少量的配置,并用include把模板配置包含进来即可。
- #
- # 值得注意的是,对于同一个配置项,redis只对最后一行的有效
- # 所以为避免模板配置覆盖当前配置,应在配置文件第一行使用include
- # 当然,如果模板配置的优先级比较高,就在配置文件最后一行使用include
- ################################ GENERAL #####################################
- # 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.
- # yes为使用守护进程,此时redis的进程ID会被写进 pidfile的配置中
- daemonize yes
- # When running daemonized, Redis writes a pid file in /var/run/redis.pid by
- # default. You can specify a custom pid file location here.
- # 当redis以守护进程的方式启动时,redis的进程ID将会写在这个文件中
- pidfile /var/run/redis.pid
- # Accept connections on the specified port, default is 6379.
- # If port 0 is specified Redis will not listen on a TCP socket.
- # redis 启动的端口。【应该知道redis是服务端吧】
- 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.
- # 最大链接缓冲池的大小,这里应该是指的未完成链接请求的数量
- #(测试值为1时,仍可以有多个链接)
- # 但该值与listen函数中的backlog意义应该是相同的,源码中该值就是被用在了listen函数中
- # 该值同时受/proc/sys/net/core/somaxconn 和 tcp_max_syn_backlog(/etc/sysctl.conf中配置)的限制
- # tcp_max_syn_backlog 指的是未完成链接的数量
- tcp-backlog 511
- # 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.
- # 绑定ip,指定ip可以连接到redis
- #
- # 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.
- #
- # 这个应该就是以文件形式创建的socket
- # unixsocket /tmp/redis.sock
- # unixsocketperm 755
- # Close the connection after a client is idle for N seconds (0 to disable)
- # 超时断链机制,如果一个链接在N秒内没有任何操作,则断开该链接
- # N为0时,该机制失效
- timeout 0
- # 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.
- # 就像心跳检测一样,检查链接是否保持正常,同时也可以保持正常链接的通信
- # 建议值为60
- #
- # A reasonable value for this option is 60 seconds.
- tcp-keepalive 0
- # 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)
- # 日志级别
- loglevel notice
- # 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
- # 日志存放路径,默认是输出到标准输出,但当以守护进程方式启动时,默认输出到/dev/null(传说中的linux黑洞)
- logfile ""
- # To enable logging to the system logger, just set 'syslog-enabled' to yes,
- # and optionally update the other syslog parameters to suit your needs.
- # yes 表示将日志写到系统日志中
- # syslog-enabled no
- # Specify the syslog identity.
- # 当syslog-enabled为yes时,指定系统日志的标示为 redis
- # syslog-ident redis
- # Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.
- # 指定系统日志的设备
- # syslog-facility local0
- # 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
- # redis的数据库格式,默认16个(0~15),默认使用第0个。
- databases 16
- ################################ SNAPSHOTTING ################################
- #
- # Save the DB on disk:
- #
- # 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.
- # 快照,即将数据写到硬盘上,在<seconds>秒内,至少有<changes>次写入数据库操作
- # 则会将数据写入硬盘一次。
- # 将save行注释掉则永远不会写入硬盘
- # save "" 表示删除所有的快照点
- #
- # 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
- # 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.
- # 当做快照失败的时候,redis会停止继续向其写入数据,保证第一时间发现redis快照出现问题
- # 当然,通过下面配置为 no,即使redis快照失败,也能继续向redis写入数据
- stop-writes-on-bgsave-error yes
- # 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.
- # 快照的时候,是否用LZF压缩,使用压缩会占一定的cpu,但不使用压缩,快照会很大
- rdbcompression yes
- # 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.
- # 数据校验,快照末尾会存放一个校验值,保证数据的准确性
- # 但数据校验会使性能下降约10%,默认开启校验
- rdbchecksum yes
- # The filename where to dump the DB
- # 快照的名字
- dbfilename dump.rdb
- # 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.
- #
- # 快照存放的目录
- # linux root下测试,会发现该进程会在当前目录下创建一个dump.rdb
- # 但快照却放在了根目录/下,重启的时候,是不会从快照中恢复数据的
- # 当把根目录下的dump.rdb文件拷贝到当前目录的时候,再次启动,就会从快照中恢复数据
- # 而且以后的快照也都在当前目录的dump.rdb中做操作
- #
- # 值得一提的是,快照是异步方式的,如果在还未达到快照的时候,修改了数据,而且redis发生问题crash了
- # 那么中间的修改数据是不会被保存到dump.rdb快照中的
- # 解决办法就是用Append Only Mode的同步模式(下面将会有该配置项)
- # 将会把每个操作写到Append Only File中,该文件也存放于当前配置的目录
- # 建议使用绝对路径!!!
- #
- dir ./
- ################################# REPLICATION #################################
- # 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.
- #
- # 主从复制,类似于双机备份。
- # 配置需指定主机的ip 和port
- # 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.
- #
- # 如果主机redis需要密码,则指定密码
- # 密码配置在下面安全配置中
- # masterauth <master-password>
- # 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.
- #
- # 当从机与主机断开时,即同步出现问题的时候,从机有两种处理方式
- # yes, 继续响应客户端请求,但可能有脏数据(过期数据、空数据等)
- # no,对客户端的请求统一回复为“SYNC with master in progress”,除了INFO和SLAVEOF命令
- slave-serve-stale-data yes
- # 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只读选项,设置从机只读(默认)。
- # 即使设置可写,当下一次从主机上同步数据,仍然会删除当前从机上写入的数据
- # 【待测试】:主机与从机互为slave会出现什么情况?
- # 【预期三种结果】:1. 提示报错 2. 主从服务器数据不可控 3. 一切正常
- slave-read-only yes
- # 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.
- #
- # 从服务器向主服务器发送心跳包,默认10发送一次
- # repl-ping-slave-period 10
- # The following option sets the replication timeout for:
- #
- # 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.
- #
- # 超时响应时间,值必须比repl-ping-slave-period大
- # 批量数据传输超时、ping超时
- # 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.
- # 主从同步是否延迟
- # yes 有延迟,约40毫秒(linux kernel的默认配置),使用较少的数据包,较小的带宽
- # no 无延迟(减少延迟),但需要更大的带宽
- 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.
- #
- # 默认情况下,当slave重连的时候,会进行全量数据同步
- # 但实际上slave只需要部分同步即可,这个选项设置部分同步的大小
- # 设置值越大,同步的时间就越长
- # 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.
- #
- # 主机的后台日志释放时间,即当没有slave连接时,过多久释放后台日志
- # 0表示不释放
- # repl-backlog-ttl 3600
- # 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.
- # 当主机crash的时候,在从机中选择一台作为主机,数字越小,优先级越高
- # 0 表示永远不作为主机,默认值是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:
- #
- # 当slave数量小于min-slaves-to-write,且延迟小于等于min-slaves-max-lag时,
- # 主机停止写入操作
- # 0表示禁用
- # 默认min-slaves-to-write为0,即禁用。min-slaves-max-lag为10
- # 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 ###################################
- # 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.
- #
- # redis密码,默认不配置,即无密码
- # 这里注意,如果设置了密码,应该设置一个复杂度比较高的密码
- # 因为redis的速度很快,每秒可以尝试150k次的密码测试,很容易对其进行暴力破解(跑码)。
- # 疑问:这里为什么不设置一个针对主机的测试次数限制的,例如每10次,则禁止建立连接1个小时!
- # requirepass foobared
- # 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.
- #
- # 命令重命名,将命令重命名为另一个字符串标识
- # 如果命令为空串(""),则会彻底禁用该命令
- # 命令重命名,会对写AOF(Append of file)文件、slave从机造成一些问题
- # 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 ####################################
- # 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'.
- #
- # 这只redis的最大连接数目,默认设置为10000个客户端
- # 当超过限制时,将段开新的连接,并响应“max number of clients reached”
- # 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').
- #
- # redis的最大内存限制,如果达到最大内存,会按照下面的maxmemory-policy进行清除
- # 如果不能再清除或者maxmemory-policy为noeviction,则对于需要增加空间的操作,将会返回错误
- # maxmemory <bytes>
- # 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
- # 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:
- #
- # 内存删除策略,默认volatile-lru,利用LRU算法,删除过期的key
- # 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.
- #
- # LRU算法与最小TTL算法只是相对精确的算法,并不是绝对精确的算法
- # 为了更精确,可以设置样本个数
- # 比如设置3个样本,redis会选取三个key,并选择删除那个上次使用时间最远的
- # maxmemory-samples 3
- ############################## APPEND ONLY MODE ###############################
- # 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.
- # 将对redis所有的操作都保存到AOF文件中
- # 因为dump.rdb是异步的,在下次快照到达之前,如果出现crash等问题,会造成数据丢失
- # 而AOF文件时同步记录的,所以会完整的恢复数据
- appendonly no
- # The name of the append only file (default: "appendonly.aof")
- # AOF文件的名字
- 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 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".
- # redis的数据同步方式,三种
- # no,redis本身不做同步,由OS来做。redis的速度会很快
- # always,在每次写操作之后,redis都进行同步,即写入AOF文件。redis会变慢,但是数据更安全
- # everysec,折衷考虑,每秒同步一次数据。【默认】
- # appendfsync always
- appendfsync everysec
- # 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).
- #
- # 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.
- # redis的同步方式中,always和everysec,快照和写AOF可能会执行大量的硬盘I/O操作,
- # 而在一些Linux的配置中,redis会阻塞很久,而redis本身并没有很好的解决这一问题。
- # 为了缓和这一问题,redis提供no-appendfsync-on-rewrite选项,
- # 即当有另外一个进程在执行保存操作的时候,redis采用no的同步方式。
- # 最坏情况下会有延迟30秒的同步延迟。
- # 如果你觉得这样做会有潜在危险,则请将该选项改为yes。否则就保持默认值no(基于稳定性考虑)。
- 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.
- # 自动重写AOF文件
- # 当AOF日志文件大小增长到指定百分比时,redis会自动隐式调用BGREWRITEAOF来重写AOF文件
- # redis会记录上次重写AOF文件之后的大小,
- # 如果当前文件大小增加了auto-aof-rewrite-percentage,则会触发重写AOF日志功能
- # 当然如果文件过小,比如小于auto-aof-rewrite-min-size这个大小,是不会触发重写AOF日志功能的
- # auto-aof-rewrite-percentage为0时,禁用重写功能
- auto-aof-rewrite-percentage 100
- auto-aof-rewrite-min-size 64mb
- ################################ LUA SCRIPTING ###############################
- # 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.
- #
- # Set it to 0 or a negative value for unlimited execution without warnings.
- # LUA脚本的最大执行时间(单位是毫秒),默认5000毫秒,即5秒
- # 如果LUA脚本执行超过这个限制,可以调用SCRIPT KILL和SHUTDOWN NOSAVE命令。
- # SCRIPT KILL可以终止脚本执行
- # SHUTDOWN NOSAVE关闭服务,防止LUA脚本的写操作发生
- # 该值为0或者负数,表示没有限制时间
- 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.
- # 记录执行比较慢的命令
- # 执行比较慢仅仅是指命令的执行时间,不包括客户端的链接与响应等时间
- # slowlog-log-slower-than 设定这个慢的时间,单位是微妙,即1000000表示1秒,0表示所有命令都记录,负数表示不记录
- # slowlog-max-len表示记录的慢命令的个数,超过限制,则最早记录的命令会被移除
- # 命令的长度没有限制,但是会消耗内存,用SLOWLOG RESET来收回这些消耗的内存
- # 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
- ################################ LATENCY MONITOR ##############################
- # The Redis latency monitoring subsystem samples different operations
- # at runtime in order to collect data related to possible sources of
- # latency of a Redis instance.
- #
- # Via the LATENCY command this information is available to the user that can
- # print graphs and obtain reports.
- #
- # The system only logs operations that were performed in a time equal or
- # greater than the amount of milliseconds specified via the
- # latency-monitor-threshold configuration directive. When its value is set
- # to zero, the latency monitor is turned off.
- #
- # By default latency monitoring is disabled since it is mostly not needed
- # if you don't have latency issues, and collecting data has a performance
- # impact, that while very small, can be measured under big load. Latency
- # monitoring can easily be enalbed at runtime using the command
- # "CONFIG SET latency-monitor-threshold <milliseconds>" if needed.
- # 延迟监控器
- # redis延迟监控子系统在运行时,会抽样检测可能导致延迟的不同操作
- # 通过LATENCY命令可以打印相关信息和报告, 命令如下(摘自源文件注释):
- # LATENCY SAMPLES: return time-latency samples for the specified event.
- # LATENCY LATEST: return the latest latency for all the events classes.
- # LATENCY DOCTOR: returns an human readable analysis of instance latency.
- # LATENCY GRAPH: provide an ASCII graph of the latency of the specified event.
- #
- # 系统只记录超过设定值的操作,单位是毫秒,0表示禁用该功能
- # 可以通过命令“CONFIG SET latency-monitor-threshold <milliseconds>” 直接设置而不需要重启redis
- latency-monitor-threshold 0
- ############################# Event notification ##############################
- # 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.
- # 事件通知,当事件发生时,redis可以通知Pub/Sub客户端
- # 空串表示禁用事件通知
- # 注意:K和E至少要指定一个,否则不会有事件通知
- notify-keyspace-events ""
- ############################### ADVANCED CONFIG ###############################
- # 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.
- # 当hash数目比较少,并且最大元素没有超过给定值时,Hash使用比较有效的内存数据结构来存储。
- # 即ziplist的结构(压缩的双向链表),参考:http://blog.csdn.net/benbendy1984/article/details/7796956
- 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配置同Hash
- 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.
- # Sets的元素如果全部是整数(10进制),且为64位有符号整数,则采用特殊的编码方式。
- # 其元素个数限制配置如下:
- 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:
- # sorted set 同Hash和List
- 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.
- # 关于HyperLogLog的介绍:http://www.redis.io/topics/data-types-intro#hyperloglogs
- # HyperLogLog稀疏表示限制设置,如果其值大于16000,则仍然采用稠密表示,因为这时稠密表示更能有效使用内存
- # 建议值为3000
- 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.
- # 每100毫秒,redis将用1毫秒的时间对Hash表进行重新Hash。
- # 采用懒惰Hash方式:操作Hash越多,则重新Hash的可能越多,若根本就不操作Hash,则不会重新Hash
- # 默认每秒10次重新hash主字典,释放可能释放的内存
- # 重新hash会造成延迟,如果对延迟要求较高,则设为no,禁止重新hash。但可能会浪费很多内存
- 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:
- #
- # 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:
- #
- # 客户端输出缓冲区限制,当客户端从服务端的读取速度不够快时,则强制断开
- # 三种不同的客户端类型:normal、salve、pubsub,语法如下:
- # 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.
- # 当达到硬限制,或者达到软限制且持续了算限制秒数,则立即与客户端断开
- # 限制设为0表示禁止该功能
- # 普通用户默认不限制
- 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.
- # redis调用内部函数执行的后台任务的频率
- # 后台任务比如:清除过期数据、客户端超时链接等
- # 默认为10,取值范围1~500,
- # 对延迟要求很低的可以设置超过100以上
- 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.
- # 当修改AOF文件时,该设置为yes,则每生成32MB的数据,就进行同步
- aof-rewrite-incremental-fsync yes
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