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redis從入門到入坑之3_配置檔案詳解

          對于主要在linux上運作的軟體或服務,對配置檔案的配置是非常重要的,着和linux的特性有關,linux在加載軟體或者服務的時候都是更具配置檔案的加載,是以配置檔案配置的是否優秀直接關系到該服務是否能夠最大限度的發揮作用。

          以下中文介紹大緻内容都是翻譯自他原來的英文(具體想知道那個配置項的作用,直接在本頁面ctrl+f搜尋即可)

# Redis configuration file example.

#

# Note that in order to read the configuration file, Redis must be

# started with the file path as first argument:

#

# 如何通過配置檔案的方式啟動redis(redis-server /配置檔案  這種啟動方式,在啟動redis時可以修改不同的配置檔案來啟動不同的redis實列)

# ./redis-server /path/to/redis.conf

# 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:

# 這裡指定了記憶體大小占比方式,1kb占是1000。位元組,而不是1024個位元組。

# 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.

################################## INCLUDES (包含,包括)###################################

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

# have a standard template that goes to all Redis servers 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.

#

# 可以在這個配置檔案中引入其他與redis相關的配置檔案,這樣可以降低單個配置檔案的配置量(在redis需要很多個性化配置的時候很有用)

# include /path/to/local.conf

# include /path/to/other.conf

################################## NETWORK(網絡) #####################################

# By default, if no "bind" configuration directive is specified, Redis listens

# for connections from all the network interfaces available on the server.

# It is possible to listen to just one or multiple selected interfaces using

# the "bind" configuration directive, followed by one or more IP addresses.

#

# Examples:

# 指定 redis 智能接受來自該ip位址的請求,如果不進行設定,name将處理所有的請求

# bind 192.168.1.100 10.0.0.1

# bind 127.0.0.1 ::1

#

# ~~~ WARNING ~~~ If the computer running Redis is directly exposed to the

# internet, binding to all the interfaces is dangerous and will expose the

# instance to everybody on the internet. So by default we uncomment the

# following bind directive, that will force Redis to listen only into

# the IPv4 lookback interface address (this means Redis will be able to

# accept connections only from clients running into the same computer it

# is running).

#

# IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES

# JUST COMMENT THE FOLLOWING LINE.

# 指定 redis 隻接收來自于該 IP 位址的請求(預設是本機),如果不進行設定,那麼将處理所有請求

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

bind 127.0.0.1

# Protected mode is a layer of security protection, in order to avoid that

# Redis instances left open on the internet are accessed and exploited.

#

# When protected mode is on and if:

#

# 1) The server is not binding explicitly to a set of addresses using the

#    "bind" directive.

# 2) No password is configured.

#

# The server only accepts connections from clients connecting from the

# IPv4 and IPv6 loopback addresses 127.0.0.1 and ::1, and from Unix domain

# sockets.

#

# By default protected mode is enabled. You should disable it only if

# you are sure you want clients from other hosts to connect to Redis

# even if no authentication is configured, nor a specific set of interfaces

# are explicitly listed using the "bind" directive.

#  3.2裡的參數,是否開啟保護模式,預設開啟。要是配置裡沒有指定bind和密碼。開啟該參數後,

# redis隻會本地進行通路,拒絕外部通路。要是開啟了密碼   和bind,可以開啟。否   則最好關閉,設定為no。

protected-mode yes

# Accept connections on the specified port, default is 6379 (IANA #815344).

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

# redis服務啟動是監聽的端口,每個配置檔案如果設定了不同的端口,在通過配置檔案啟動redis時就能夠啟動多個redis實列

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.

# 此參數确定了TCP連接配接中已完成隊列(完成三次握手之後)的長度,(隊列的長度) 此值必須不大于Linux系統定義

#的/proc/sys/net/core/somaxconn值,

# 預設是511,而Linux的預設參數值是128。當系統并發量大并且用戶端速度緩慢的時候,可以将這二個參數一起參考設定。該内#核參數預設值一般是128

# ,對于負載很大的服務程式來說大大的不夠。一般會将它修改為2048或者更大。在/etc/sysctl.conf中添加:net.core.somaxconn = 2048,

# 然後在終端中執行sysctl -p。

tcp-backlog 511

# Unix socket.

#

# 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.

# 配置unix socket來讓redis支援監聽本地連接配接。

# unixsocket /tmp/redis.sock

# 配置unix socket使用檔案的權限

# unixsocketperm 700

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

# 此參數為設定用戶端空閑超過timeout,服務端會斷開連接配接,為0則服務端不會主動斷開連接配接,不能小于0。

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.

#

# A reasonable value for this option is 300 seconds, which is the new

# Redis default starting with Redis 3.2.1.

# tcp keepalive參數。如果設定不為0,就使用配置tcp的SO_KEEPALIVE值,使用keepalive有兩個好處:

# 1檢測死對等體。

# 2從網絡的角度來看連接配接是否存在

# 該值的合理值為300秒

# 降低中間裝置出問題而導緻網絡看似連接配接卻已經與對端端口的問題。

# 在Linux核心中,設定了keepalive,redis會定時給對端發送ack。檢測到對端關閉需要兩倍的設定值。

tcp-keepalive 300

################################# GENERAL(通用) #####################################

# 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.

# 是否背景運作

daemonize yes

# If you run Redis from upstart or systemd, Redis can interact with your

# supervision tree. Options:

#   supervised no      - no supervision interaction

#   supervised upstart - signal upstart by putting Redis into SIGSTOP mode

#   supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET

#   supervised auto    - detect upstart or systemd method based on

#                        UPSTART_JOB or NOTIFY_SOCKET environment variables

# Note: these supervision methods only signal "process is ready."

#       They do not enable continuous liveness pings back to your supervisor.

# redis的監聽模式,這個我也不清楚

supervised no

# If a pid file is specified, Redis writes it where specified at startup

# and removes it at exit.

#

# When the server runs non daemonized, no pid file is created if none is

# specified in the configuration. When the server is daemonized, the pid file

# is used even if not specified, defaulting to "/var/run/redis.pid".

#

# Creating a pid file is best effort: if Redis is not able to create it

# nothing bad happens, the server will start and run normally.

# redis程序檔案所在位置

pidfile /var/run/redis_6379.pid

# 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)

# redis的日志記錄級别

# 通常有

# debug(很多資訊,友善開發、測試)

# verbose(許多有用的資訊,但是沒有debug級别資訊多)

# notice(适當的日志級别,适合生産環境)

# warn(隻有非常重要的資訊)

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

# 日志檔案所在位置,如果沒有設定,日志會列印到标準輸出裝置。背景運作的redis标準輸出是/dev/null。

logfile /var/log/redis/redis.log

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

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

# 要啟用日志記錄到系統記錄器,隻需将'syslog-enabled'設定為yes,一般不建議

# syslog-enabled no

# Specify the syslog identity.

# syslog的辨別符

# syslog-ident redis

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

# 日志的來源、裝置

# 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

# 預設有多少個庫

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.

#

#   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 completely by commenting out all "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 ""

#  将資料持久化到磁盤的條件

#  900秒(15分鐘)後,如果至少更改了1個鍵

#  30秒後(5分鐘)如果至少改變了10個鍵

#  60秒後如果至少改變了10000個鍵

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.

# 當RDB持久化出現錯誤後,是否依然進行繼續進行工作,yes:不能進行工作,

# no:可以繼續進行工作,可以通過info中的rdb_last_bgsave_status了解RDB持久化是否有錯誤

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.

# rdb是否啟用壓縮,啟用對cpu占用比較高,但是節約磁盤空間

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.

# 是否需要校驗rdb檔案

rdbchecksum yes

# The filename where to dump the DB

# rdb檔案的名稱

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.

# 資料目錄,資料庫的寫入會在這個目錄。rdb、aof檔案也會寫在這個目錄

dir /var/lib/redis

################################# REPLICATION(主從複制,讀寫分離相關)#################################

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

# another Redis server. A few things to understand ASAP about Redis replication.

#

# 1) Redis replication is asynchronous, but you can configure a master to

#    stop accepting writes if it appears to be not connected with at least

#    a given number of slaves.

# 2) Redis slaves are able to perform a partial resynchronization with the

#    master if the replication link is lost for a relatively small amount of

#    time. You may want to configure the replication backlog size (see the next

#    sections of this file) with a sensible value depending on your needs.

# 3) Replication is automatic and does not need user intervention. After a

#    network partition slaves automatically try to reconnect to masters

#    and resynchronize with them.

# 複制選項,slave複制對應的master。

# 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設定了requirepass,那麼slave要連上master,需要有master的密碼才行。 (master的登入密碼)

# 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.

# 當從庫同主機失去連接配接或者複制正在進行,從機庫有兩種運作方式

# 1 :為yes 從機繼續響應用戶端的請求

# 2 :為no  除去INFO和SLAVOF指令之外的任何請求都會傳回一個錯誤”SYNC with master in progress”。

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.

# 作為從機,預設是隻讀的,可以修改為no讓其可以寫(主從是不能這樣,也不建議這樣)

slave-read-only yes

# Replication SYNC strategy: disk or socket.

#

# -------------------------------------------------------

# WARNING: DISKLESS REPLICATION IS EXPERIMENTAL CURRENTLY

# -------------------------------------------------------

#

# New slaves and reconnecting slaves that are not able to continue the replication

# process just receiving differences, need to do what is called a "full

# synchronization". An RDB file is transmitted from the master to the slaves.

# The transmission can happen in two different ways:

#

# 1) Disk-backed: The Redis master creates a new process that writes the RDB

#                 file on disk. Later the file is transferred by the parent

#                 process to the slaves incrementally.

# 2) Diskless: The Redis master creates a new process that directly writes the

#              RDB file to slave sockets, without touching the disk at all.

#

# With disk-backed replication, while the RDB file is generated, more slaves

# can be queued and served with the RDB file as soon as the current child producing

# the RDB file finishes its work. With diskless replication instead once

# the transfer starts, new slaves arriving will be queued and a new transfer

# will start when the current one terminates.

#

# When diskless replication is used, the master waits a configurable amount of

# time (in seconds) before starting the transfer in the hope that multiple slaves

# will arrive and the transfer can be parallelized.

#

# With slow disks and fast (large bandwidth) networks, diskless replication

# works better.

# 從機持久化的兩個方式。

# disk  -->disk方式是master建立一個新的程序把rdb檔案儲存到磁盤,再把磁盤上的rdb檔案傳遞給slave。

# 和

# socket  --> socket是master建立一個新的程序,直接把rdb檔案以socket的方式發給slave。

# 這裡用的就是socket方式,disk的方式存在機器磁盤io的問題

repl-diskless-sync no

# When diskless replication is enabled, it is possible to configure the delay

# the server waits in order to spawn the child that transfers the RDB via socket

# to the slaves.

#

# This is important since once the transfer starts, it is not possible to serve

# new slaves arriving, that will be queued for the next RDB transfer, so the server

# waits a delay in order to let more slaves arrive.

#

# The delay is specified in seconds, and by default is 5 seconds. To disable

# it entirely just set it to 0 seconds and the transfer will start ASAP.

# diskless複制的延遲時間,防止設定為0。一旦複制開始,節點不會再接收新slave的複制請求直到下一個rdb傳輸。是以最好等待一段時間,等更多的slave連上來。

repl-diskless-sync-delay 5

# 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.

# slave根據指定的時間間隔向伺服器發送ping請求。時間間隔可以通過 repl_ping_slave_period 來設定,預設10秒

# 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.

#master檢測到slave上次發送的時間超過repl-timeout,即認為slave離線,清除該slave資訊。slave檢測到上次和master互動的時間超過repl-timeout,

# 則認為master離線。需要注意的是repl-timeout需要設定一個比repl-ping-slave-period更大的值,不然會經常檢測到逾時。

# 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.

# 這裡配置為no時,主從時資料的延遲會比較小

# 如果master設定了yes來禁止tcp nodelay設定,在把資料複制給slave的時候,會減少包的數量和更小的網絡帶寬。但是這也可能帶來資料的延遲。

# 預設我們推薦更小的延遲,但是在資料量傳輸很大的場景下,建議選擇yes。

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 bigger 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.

# 複制緩沖區大小,這是一個環形複制緩沖區

# 這樣在slave離線的時候,不需要完全複制master的資料,如果可以執行部分同步,隻需要把緩沖區的部分資料複制給slave,就能恢複正常複制狀态。

# 複制緩沖區隻有在有slave連接配接的時候才配置設定記憶體。沒有slave的一段時間,記憶體會被釋放出來,預設1m。

# 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.

# master沒有slave一段時間會釋放複制緩沖區的記憶體,repl-backlog-ttl用來設定該時間長度。機關為秒

# 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.

# 當master不可用,Sentinel(哨兵模式)會根據slave的優先級選舉一個master。

# 最低的優先級的slave,當選master。而配置成0,永遠不會被選中。

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 GUARANTEE 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:

# 主站可以停止接受寫請求,當與它連接配接的從站少于N個,滞後少于M秒,N個從站必須是線上狀态。

#  延遲的秒數必須<=所定義的值,延遲秒數是從最後一次收到的來自從站的ping開始計算。ping通常是每秒一次。

#   這一選項并不保證N個備份都會接受寫請求,但是會限制在指定秒數内由于從站數量不夠導緻的寫操作丢失的情況。

#   如果想要至少3個從站且延遲少于10秒,就按照如下配置

# 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.

# A Redis master is able to list the address and port of the attached

# slaves in different ways. For example the "INFO replication" section

# offers this information, which is used, among other tools, by

# Redis Sentinel in order to discover slave instances.

# Another place where this info is available is in the output of the

# "ROLE" command of a masteer.

#

# The listed IP and address normally reported by a slave is obtained

# in the following way:

#

#   IP: The address is auto detected by checking the peer address

#   of the socket used by the slave to connect with the master.

#

#   Port: The port is communicated by the slave during the replication

#   handshake, and is normally the port that the slave is using to

#   list for connections.

#

# However when port forwarding or Network Address Translation (NAT) is

# used, the slave may be actually reachable via different IP and port

# pairs. The following two options can be used by a slave in order to

# report to its master a specific set of IP and port, so that both INFO

# and ROLE will report those values.

#

# There is no need to use both the options if you need to override just

# the port or the IP address.

#

# slave-announce-ip 5.5.5.5

# slave-announce-port 1234

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

#

# 可以讓使用者使用AUTH指令來認證密碼,才能使用其他指令。

# requirepass foobared

requirepass 12345

# 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(範圍) ####################################

# 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'.

#

# 最大用戶端連接配接數量

# 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').

#  指定Redis最大記憶體限制,Redis在啟動時會把資料加載到記憶體中,達到最大記憶體後,Redis會先嘗試清除已到期或即将到期的

# Key

#  當此方法處理 後,仍然到達最大記憶體設定,将無法再進行寫入操作,但仍然可以進行讀取操作。Redis新的vm機制,

#  會把Key存放記憶體,Value會存放在swap區

# 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

# #volatile-lru:利用LRU算法移除設定過過期時間的key。

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

# allkeys-lru:利用LRU算法移除任何key。

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

# volatile-random:随機移除設定過過期時間的key。

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

# allkeys-random:随機移除任何key。

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

# volatile-ttl:移除即将過期的key,根據最近過期時間來删除(輔以TTL)

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

# noeviction:不移除任何key,隻是傳回一個寫錯誤。

#

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

#       operations, when there are no suitable keys for eviction.

#

#       At the date of writing these 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:

# 同上

# maxmemory-policy noeviction

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

# algorithms (in order to save memory), so you can tune it for speed or

# accuracy. For default Redis will check five keys and pick the one that was

# used less recently, you can change the sample size using the following

# configuration directive.

#

# The default of 5 produces good enough results. 10 Approximates very closely

# true LRU but costs a bit more CPU. 3 is very fast but not very accurate.

#  LRU 和 minimal TTL 算法都不是精準的算法,但是相對精确的算法(為了節省記憶體)

#  随意你可以選擇樣本大小進行檢,redis預設選擇5個樣本進行檢測,你可以通過maxmemory-samples進行設定樣本數

# maxmemory-samples 5

############################## APPEND ONLY MODE(aof相關) ###############################

# 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.

# 是否開啟了aof的持久化方式

appendonly no

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

# aof的名稱

appendfilename "appendonly.aof"

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

# instead of waiting 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".

# aof持久化政策的配置

# no表示不執行fsync,由作業系統保證資料同步到磁盤,速度最快。

# always表示每次寫入都執行fsync,以保證資料同步到磁盤。

# everysec表示每秒執行一次fsync,可能會導緻丢失這1s資料。

# appendfsync always

# appendfsync no

appendfsync everysec

# 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.

# 根據sync函數來同步資料,linux中這個參數一般為30s,是以可能會丢失30s的資料

# 摘要

# 如果對延遲要求很高的應用,這個字段可以設定為yes,否則還是設定為no,這樣對持久化特性來說這是更安全的選擇。

# 設定為yes表示rewrite期間對新寫操作不fsync,暫時存在記憶體中,等rewrite完成後再寫入,

# 預設為no,建議yes。Linux的預設fsync政策是30秒。可能丢失30秒資料。

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.

# 即當aof檔案增長到一定大小的時候Redis能夠調用bgrewriteaof對日志檔案進行重寫。

# 目前AOF檔案大小是上次日志重寫得到AOF檔案大小的二倍(設定為100)時,自動啟動新的日志重寫過程。

auto-aof-rewrite-percentage 100

# 設定允許重寫的最小aof檔案大小,避免了達到約定百分比但尺寸仍然很小的情況還要重寫

auto-aof-rewrite-min-size 64mb

# An AOF file may be found to be truncated at the end during the Redis

# startup process, when the AOF data gets loaded back into memory.

# This may happen when the system where Redis is running

# crashes, especially when an ext4 filesystem is mounted without the

# data=ordered option (however this can't happen when Redis itself

# crashes or aborts but the operating system still works correctly).

#

# Redis can either exit with an error when this happens, or load as much

# data as possible (the default now) and start if the AOF file is found

# to be truncated at the end. The following option controls this behavior.

#

# If aof-load-truncated is set to yes, a truncated AOF file is loaded and

# the Redis server starts emitting a log to inform the user of the event.

# Otherwise if the option is set to no, the server aborts with an error

# and refuses to start. When the option is set to no, the user requires

# to fix the AOF file using the "redis-check-aof" utility before to restart

# the server.

#

# Note that if the AOF file will be found to be corrupted in the middle

# the server will still exit with an error. This option only applies when

# Redis will try to read more data from the AOF file but not enough bytes

# will be found.

# aof檔案可能在尾部是不完整的,當redis啟動的時候,aof檔案的資料被載入記憶體。

#  重新開機可能發生在redis所在的主機作業系統當機後,尤其在ext4檔案系統沒有加上data=ordered選項,出現這種現象

#  redis當機或者異常終止不會造成尾部不完整現象,可以選擇讓redis退出,或者導入盡可能多的資料。

#  如果選擇的是yes,當截斷的aof檔案被導入的時候,會自動釋出一個log給用戶端然後load。

#  如果是no,使用者必須手動redis-check-aof修複AOF檔案才可以。

aof-load-truncated yes

################################ LUA SCRIPTING lua腳本 ###############################

# 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 exceeds 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 command was

# already issued by the script but the user doesn't want to wait for the natural

# termination of the script.

#

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

# 摘要

# 如果達到最大時間限制(毫秒),redis會記個log,然後傳回error。當一個腳本超過了最大時限。

隻有SCRIPT KILL和SHUTDOWN NOSAVE可以用。第一個可以殺沒有調write指令的東西。要是已經調用了write,隻能用第二個指令殺。

lua-time-limit 5000

################################ REDIS CLUSTER 簇 ###############################

#

# ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

# WARNING EXPERIMENTAL: Redis Cluster is considered to be stable code, however

# in order to mark it as "mature" we need to wait for a non trivial percentage

# of users to deploy it in production.

# ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

#

# Normal Redis instances can't be part of a Redis Cluster; only nodes that are

# started as cluster nodes can. In order to start a Redis instance as a

# cluster node enable the cluster support uncommenting the following:

# 叢集開關,預設是不開啟叢集模式

# cluster-enabled yes

# Every cluster node has a cluster configuration file. This file is not

# intended to be edited by hand. It is created and updated by Redis nodes.

# Every Redis Cluster node requires a different cluster configuration file.

# Make sure that instances running in the same system do not have

# overlapping cluster configuration file names.

# 叢集配置檔案的名稱,每個節點都有一個叢集相關的配置檔案,持久化儲存叢集的資訊。

# 這個檔案并不需要手動配置,這個配置檔案有Redis生成并更新,

# 每個Redis叢集節點需要一個單獨的配置檔案,請確定與執行個體運作的系統中配置檔案名稱不沖突

# cluster-config-file nodes-6379.conf

# Cluster node timeout is the amount of milliseconds a node must be unreachable

# for it to be considered in failure state.

# Most other internal time limits are multiple of the node timeout.

# 節點互連逾時的閥值。叢集節點逾時毫秒數

# cluster-node-timeout 15000

# A slave of a failing master will avoid to start a failover if its data

# looks too old.

#

# There is no simple way for a slave to actually have a exact measure of

# its "data age", so the following two checks are performed:

#

# 1) If there are multiple slaves able to failover, they exchange messages

#    in order to try to give an advantage to the slave with the best

#    replication offset (more data from the master processed).

#    Slaves will try to get their rank by offset, and apply to the start

#    of the failover a delay proportional to their rank.

#

# 2) Every single slave computes the time of the last interaction with

#    its master. This can be the last ping or command received (if the master

#    is still in the "connected" state), or the time that elapsed since the

#    disconnection with the master (if the replication link is currently down).

#    If the last interaction is too old, the slave will not try to failover

#    at all.

#

# The point "2" can be tuned by user. Specifically a slave will not perform

# the failover if, since the last interaction with the master, the time

# elapsed is greater than:

#

#   (node-timeout * slave-validity-factor) + repl-ping-slave-period

#

# So for example if node-timeout is 30 seconds, and the slave-validity-factor

# is 10, and assuming a default repl-ping-slave-period of 10 seconds, the

# slave will not try to failover if it was not able to talk with the master

# for longer than 310 seconds.

#

# A large slave-validity-factor may allow slaves with too old data to failover

# a master, while a too small value may prevent the cluster from being able to

# elect a slave at all.

#

# For maximum availability, it is possible to set the slave-validity-factor

# to a value of 0, which means, that slaves will always try to failover the

# master regardless of the last time they interacted with the master.

# (However they'll always try to apply a delay proportional to their

# offset rank).

#

# Zero is the only value able to guarantee that when all the partitions heal

# the cluster will always be able to continue.

#

# cluster-slave-validity-factor 10

# Cluster slaves are able to migrate to orphaned masters, that are masters

# that are left without working slaves. This improves the cluster ability

# to resist to failures as otherwise an orphaned master can't be failed over

# in case of failure if it has no working slaves.

#

# Slaves migrate to orphaned masters only if there are still at least a

# given number of other working slaves for their old master. This number

# is the "migration barrier". A migration barrier of 1 means that a slave

# will migrate only if there is at least 1 other working slave for its master

# and so forth. It usually reflects the number of slaves you want for every

# master in your cluster.

#

# Default is 1 (slaves migrate only if their masters remain with at least

# one slave). To disable migration just set it to a very large value.

# A value of 0 can be set but is useful only for debugging and dangerous

# in production.

# 如這個參數若被設為2,那麼隻有當一個主節點擁有2 個可工作的從節點時,它的一個從節點會嘗試遷移。

# cluster-migration-barrier 1

# By default Redis Cluster nodes stop accepting queries if they detect there

# is at least an hash slot uncovered (no available node is serving it).

# This way if the cluster is partially down (for example a range of hash slots

# are no longer covered) all the cluster becomes, eventually, unavailable.

# It automatically returns available as soon as all the slots are covered again.

#

# However sometimes you want the subset of the cluster which is working,

# to continue to accept queries for the part of the key space that is still

# covered. In order to do so, just set the cluster-require-full-coverage

# option to no.

#  預設情況下,叢集全部的slot有節點負責,叢集狀态才為ok,才能提供服務。設定為no,可以在slot沒有全部配置設定的時候提供服務。

# 不建議打開該配置,這樣會造成分區的時候,小分區的master一直在接受寫請求,而造成很長時間資料不一緻

# cluster-require-full-coverage yes

# In order to setup your cluster make sure to read the documentation

# available at http://redis.io web site.

################################## SLOW LOG 慢日志 ###################################

# 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.

# 執行時間比slowlog-log-slower-than大的請求記錄到slowlog裡面,機關是微秒,是以1000000就是1秒。

# 注意,負數時間會禁用慢查詢日志,而0則會強制記錄所有指令

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.

# 慢查詢日志長度。當一個新的指令被寫進日志的時候,最老的那個記錄會被删掉。

# 這個長度沒有限制。隻要有足夠的記憶體就行。你可以通過 SLOWLOG RESET 來釋放記憶體

slowlog-max-len 128

################################ LATENCY MONITOR (延遲監控)##############################

# 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 enabled at runtime using the command

# "CONFIG SET latency-monitor-threshold <milliseconds>" if needed.

# 用來監控redis中執行比較緩慢的一些操作,用LATENCY列印redis執行個體在跑指令時的耗時圖表。隻記錄大于等于下邊設定的值

# 的操作。0的話,就是關閉監視。

# 預設延遲監控功能是關閉的,如果你需要打開,也可以通過CONFIG SET指令動态設定

latency-monitor-threshold 0

############################# 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/notifications

#

# 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 [email protected]__:foo del

# PUBLISH [email protected]__: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 [email protected]<db>__ prefix.

#  E     Keyevent events, published with [email protected]<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

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

#  are disabled.

#

#  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 [email protected]__: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 ###############################

# 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.

#  ziplist的特點就是檔案存儲(以及記憶體存儲)所需的空間較小,在内容較小時,性能和hashtable幾乎一樣。

#  是以redis對hash類型預設采取ziplist。

# 資料量小于等于hash-max-ziplist-entries的用ziplist這種資料結構,大于hash-max-ziplist-entries将資料類型重構為hash

hash-max-ziplist-entries 512

#  ziplist中允許條目value值最大位元組數,預設為64,建議為1024

# value大小小于等于hash-max-ziplist-value的用ziplist,大于hash-max-ziplist-value用hash。

hash-max-ziplist-value 64

#也上兩個也是在大資料量時的優化點,大資料量時ziplist這種資料結構的性能會大大的下降是以這個值的設定要适當

# Lists are also encoded in a special way to save a lot of space.

# The number of entries allowed per internal list node can be specified

# as a fixed maximum size or a maximum number of elements.

# For a fixed maximum size, use -5 through -1, meaning:

# -5: max size: 64 Kb  <-- not recommended for normal workloads

# -4: max size: 32 Kb  <-- not recommended

# -3: max size: 16 Kb  <-- probably not recommended

# -2: max size: 8 Kb   <-- good

# -1: max size: 4 Kb   <-- good

# Positive numbers mean store up to _exactly_ that number of elements

# per list node.

# The highest performing option is usually -2 (8 Kb size) or -1 (4 Kb size),

# but if your use case is unique, adjust the settings as necessary.

# 當取正值的時候,表示按照資料項個數來限定每個quicklist節點上的ziplist長度。比如,當這個參數配置成5的時候,表示每個

# quicklist節點的ziplist最多包含5個資料項。

 # 當取負值的時候,表示按照占用位元組數來限定每個quicklist節點上的ziplist長度。這時,它隻能取-1到-5這五個值,每個值含 義 # 如下:

   #  -5: 每個quicklist節點上的ziplist大小不能超過64 Kb。(注:1kb => 1024 bytes)

    # -4: 每個quicklist節點上的ziplist大小不能超過32 Kb。

    # -3: 每個quicklist節點上的ziplist大小不能超過16 Kb。

    # -2: 每個quicklist節點上的ziplist大小不能超過8 Kb。(-2是Redis給出的預設值)

    # -1: 每個quicklist節點上的ziplist大小不能超過4 Kb。

list-max-ziplist-size -2

# Lists may also be compressed.

# Compress depth is the number of quicklist ziplist nodes from *each* side of

# the list to *exclude* from compression.  The head and tail of the list

# are always uncompressed for fast push/pop operations.  Settings are:

# 0: disable all list compression

# 1: depth 1 means "don't start compressing until after 1 node into the list,

#    going from either the head or tail"

#    So: [head]->node->node->...->node->[tail]

#    [head], [tail] will always be uncompressed; inner nodes will compress.

# 2: [head]->[next]->node->node->...->node->[prev]->[tail]

#    2 here means: don't compress head or head->next or tail->prev or tail,

#    but compress all nodes between them.

# 3: [head]->[next]->[next]->node->node->...->node->[prev]->[prev]->[tail]

# etc.

#這個參數表示一個quicklist兩端不被壓縮的節點個數。

#注:這裡的節點個數是指quicklist雙向連結清單的節點個數,而不是指ziplist裡面的資料項個數。

#實際上,一個quicklist節點上的ziplist,如果被壓縮,就是整體被壓縮的。

#參數list-compress-depth的取值含義如下:

    #0: 是個特殊值,表示都不壓縮。這是Redis的預設值。

    #1: 表示quicklist兩端各有1個節點不壓縮,中間的節點壓縮。

    #2: 表示quicklist兩端各有2個節點不壓縮,中間的節點壓縮。

    #3: 表示quicklist兩端各有3個節點不壓縮,中間的節點壓縮。

    #依此類推…

#由于0是個特殊值,很容易看出quicklist的頭節點和尾節點總是不被壓縮的,以便于在表的兩端進行快速存取

list-compress-depth 0

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

# of just strings that happen 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.

#  資料量小于等于set-max-intset-entries用intset,大于set-max-intset-entries用set

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:

# 資料量小于等于zset-max-ziplist-entries用ziplist,大于zset-max-ziplist-entries用zset

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.

# 指定稀疏或者稠密的資料結構

# value大小小于等于hll-sparse-max-bytes使用稀疏資料結構(sparse),大于hll-sparse-max-bytes使用稠密的資料結構(dense)。

# 一個比16000大的value是幾乎沒用的,建議的value大概為3000。如果對CPU要求不高,對空間要求較高的,建議設定到10000左右。

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

# actively rehash 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 from 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.

# Redis将在每100毫秒時使用1毫秒的CPU時間來對redis的hash表進行重新hash,可以降低記憶體的使用。當你的使用場景中,有非常嚴格的實時性需要,

# 不能夠接受Redis時不時的對請求有2毫秒的延遲的話,把這項配置為no。如果沒有這麼嚴格的實時性要求,可以設定為yes,以便能夠盡可能快的釋放記憶體。

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:

#

# 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 according 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.

# (赫茲)redis執行任務的頻率為1s除以hz。

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.

# 在aof重寫的時候,如果打開了aof-rewrite-incremental-fsync開關,

# 系統會每32MB執行一次fsync。這對于把檔案寫入磁盤是有幫助的,可以避免過大的延遲峰值。

aof-rewrite-incremental-fsync yes

上述的一些配置解釋我也是參考 (https://www.cnblogs.com/pqchao/p/6558688.html)這個部落客的,大家可以看看

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