Redis基础

安装

Mac中安装 Redis

brew方式安装 Redis

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# 安装Redis
$ brew install redis
# 运行 Redis
$ redis-server
# 后台运行 Redis
$ brew services start redis
# 停止后台运行 Redis
$ brew services stop redis
# 非后台运行 Redis
$ redis-server /usr/local/etc/redis.conf
# 检查 Redis 是否在运行
$ lsof -i tcp:6379
# 运行客户端
$ redis-cli

编译安装

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$ $ wget http://download.redis.io/releases/redis-4.0.10.tar.gz
$ tar xzf redis-4.0.10.tar.gz
$ cd redis-4.0.10
$ make

CentOS7中安装Redis

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$ yum update
$ yum install epel-release
$ yum install redis
$ systemctl start redis
$ systemctl enable redis
# 验证是否安装成功
$ redis-cli
127.0.0.1:6379> ping
PONG
127.0.0.1:6379>

Ubuntu中安装Redis

方式1

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# 安装
$ sudo apt-get update
$ sudo apt-get install redis-server
# 启动
$ sudo /etc/init.d/redis-server start

方式2

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$

程序说明

路径 说明
/usr/local/bin/redis-server Redis服务器
/usr/local/bin/redis-cli 命令行客户端
/usr/local/bin/redis-benchmark Redis的性能测试工具
/usr/local/bin/redis-check-aof AOF文件修复工具
/usr/local/bin/redis-check-dump RDB文件检测工具
/usr/local/bin/redis-sentinel 启动redis-sentinel
/usr/local/bin/redis.conf Redis的配置文件

图形客户端

Ubuntu中安装redis-desktop-manager

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$ sudo snap install redis-desktop-manager

配置

配置持久化

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appendonly yes
appendfsync everysec
# 重启Redis

配置登陆密码

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requirepass 密码

配置允许远程访问

  • 将bind 127.0.0.1注释掉,或修改成允许访问的远程机器的ip地址。
  • 在redis3.2之后,redis增加了protected-mode,将 protected-mode yes 修改为 protected-mode no

配置后端模式启动

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daemonize yes

系统调优

方法1:立即生效

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$ sysctl vm.overcommit_memory=1

方法2:重启生效

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$ vi /etc/sysctl.config

增加如下配置:

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vm.overcommit_memory = 1

运维

连接 Redis

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$ redis-cli -h 127.0.0.1 -p 6379
$ auth "password"

备份

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127.0.0.1:6379> SAVE
# 获取redis的安装目录
127.0.0.1:6379> CONFIG GET dir

备份完成后会在安装目录下(默认/var/lib/redis/)创建dump.rdb文件

恢复

将备份文件(dump.rdb)移动到redis安装目录,并启动redis服务即可,redis会自动加载并恢复dumop.rdb中的数据。

Redis配置文件样例

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# Note on units: when memory size is needed, it is possible to specifiy
# it in the usual form of 1k 5GB 4M and so forth:
#
# 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.

# Redis默认不是以守护进程的方式运行,可以通过该配置项修改,使用yes启用守护进程
# 启用守护进程后,Redis会把pid写到一个pidfile中,在/var/run/redis.pid
daemonize no

# 当Redis以守护进程方式运行时,Redis默认会把pid写入/var/run/redis.pid文件,可以通过pidfile指定
pidfile /var/run/redis.pid

# 指定Redis监听端口,默认端口为6379
# 如果指定0端口,表示Redis不监听TCP连接
port 6379

# 绑定的主机地址
# 你可以绑定单一接口,如果没有绑定,所有接口都会监听到来的连接
# bind 127.0.0.1

# Specify the path for the unix socket that will be used to listen for
# incoming connections. There is no default, so Redis will not listen
# on a unix socket when not specified.
#
# unixsocket /tmp/redis.sock
# unixsocketperm 755

# 当客户端闲置多长时间后关闭连接,如果指定为0,表示关闭该功能
timeout 0

# 指定日志记录级别,Redis总共支持四个级别:debug、verbose、notice、warning,默认为verbose
# debug (很多信息, 对开发/测试比较有用)
# verbose (many rarely useful info, but not a mess like the debug level)
# notice (moderately verbose, what you want in production probably)
# warning (only very important / critical messages are logged)
loglevel verbose

# 日志记录方式,默认为标准输出,如果配置为redis为守护进程方式运行,而这里又配置为标准输出,则日志将会发送给/dev/null
logfile stdout

# To enable logging to the system logger, just set 'syslog-enabled' to yes,
# and optionally update the other syslog parameters to suit your needs.
# syslog-enabled no

# Specify the syslog identity.
# syslog-ident redis

# Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.
# syslog-facility local0

# 设置数据库的数量,默认数据库为0,可以使用select <dbid>命令在连接上指定数据库id
# dbid是从0到‘databases’-1的数目
databases 16

################################ SNAPSHOTTING #################################
# 指定在多长时间内,有多少次更新操作,就将数据同步到数据文件,可以多个条件配合
# 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.
#
# 满足以下条件将会同步数据:
# 900秒(15分钟)内有1个更改
# 300秒(5分钟)内有10个更改
# 60秒内有10000个更改
# Note: 可以把所有“save”行注释掉,这样就取消同步操作了

save 900 1
save 300 10
save 60 10000

# 指定存储至本地数据库时是否压缩数据,默认为yes,Redis采用LZF压缩,如果为了节省CPU时间,可以关闭该选项,但会导致数据库文件变的巨大
rdbcompression yes

# 指定本地数据库文件名,默认值为dump.rdb
dbfilename dump.rdb

# 工作目录.
# 指定本地数据库存放目录,文件名由上一个dbfilename配置项指定
#
# Also the Append Only File will be created inside this directory.
#
# 注意,这里只能指定一个目录,不能指定文件名
dir ./

################################# REPLICATION #################################

# 主从复制。使用slaveof从 Redis服务器复制一个Redis实例。注意,该配置仅限于当前slave有效
# 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.
# 设置当本机为slav服务时,设置master服务的ip地址及端口,在Redis启动时,它会自动从master进行数据同步
# slaveof <masterip> <masterport>


# 当master服务设置了密码保护时,slav服务连接master的密码
# 下文的“requirepass”配置项可以指定密码
# masterauth <master-password>

# When a slave lost the 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 data data, or the
# data set may just be empty if this is the first synchronization.
#
# 2) if slave-serve-stale data is set to 'no' the slave will reply with
# an error "SYNC with master in progress" to all the kind of commands
# but to INFO and SLAVEOF.
#
slave-serve-stale-data yes

# Slaves send PINGs to server in a predefined interval. It's possible to change
# this interval with the repl_ping_slave_period option. The default value is 10
# seconds.
#
# repl-ping-slave-period 10

# The following option sets a timeout for both Bulk transfer I/O timeout and
# master data or ping response timeout. The default value is 60 seconds.
#
# It is important to make sure that this value is greater than the value
# specified for repl-ping-slave-period otherwise a timeout will be detected
# every time there is low traffic between the master and the slave.
#
# repl-timeout 60

################################## SECURITY ###################################

# Warning: since Redis is pretty fast an outside user can try up to
# 150k passwords per second against a good box. This means that you should
# use a very strong password otherwise it will be very easy to break.
# 设置Redis连接密码,如果配置了连接密码,客户端在连接Redis时需要通过auth <password>命令提供密码,默认关闭
# requirepass foobared

# Command renaming.
#
# It is possilbe to change the name of dangerous commands in a shared
# environment. For instance the CONFIG command may be renamed into something
# of hard to guess so that it will be still available for internal-use
# tools but not available for general clients.
#
# Example:
#
# rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52
#
# It is also possilbe to completely kill a command renaming it into
# an empty string:
#
# rename-command CONFIG ""

################################### LIMITS ####################################

# 设置同一时间最大客户端连接数,默认无限制,Redis可以同时打开的客户端连接数为Redis进程可以打开的最大文件描述符数,
# 如果设置maxclients 0,表示不作限制。当客户端连接数到达限制时,Redis会关闭新的连接并向客户端返回max Number of clients reached错误信息
# maxclients 128

# Don't use more memory than the specified amount of bytes.
# When the memory limit is reached Redis will try to remove keys with an
# EXPIRE set. It will try to start freeing keys that are going to expire
# in little time and preserve keys with a longer time to live.
# Redis will also try to remove objects from free lists if possible.
#
# If all this fails, Redis will start to reply with errors to commands
# that will use more memory, like SET, LPUSH, and so on, and will continue
# to reply to most read-only commands like GET.
#
# WARNING: maxmemory can be a good idea mainly if you want to use Redis as a
# 'state' server or cache, not as a real DB. When Redis is used as a real
# database the memory usage will grow over the weeks, it will be obvious if
# it is going to use too much memory in the long run, and you'll have the time
# to upgrade. With maxmemory after the limit is reached you'll start to get
# errors for write operations, and this may even lead to DB inconsistency.
# 指定Redis最大内存限制,Redis在启动时会把数据加载到内存中,达到最大内存后,Redis会先尝试清除已到期或即将到期的Key,
# 当此方法处理后,仍然到达最大内存设置,将无法再进行写入操作,但仍然可以进行读取操作。
# Redis新的vm机制,会把Key存放内存,Value会存放在swap区
# maxmemory <bytes>

# MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
# is reached? You can select among five behavior:
#
# 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 all the kind of 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:
#
# maxmemory-policy volatile-lru

# LRU and minimal TTL algorithms are not precise algorithms but approximated
# algorithms (in order to save memory), so you can select as well the sample
# size to check. For instance for default Redis will check three keys and
# pick the one that was used less recently, you can change the sample size
# using the following configuration directive.
#
# maxmemory-samples 3

############################## APPEND ONLY MODE ###############################

#
# Note that you can have both the async dumps and the append only file if you
# like (you have to comment the "save" statements above to disable the dumps).
# Still if append only mode is enabled Redis will load the data from the
# log file at startup ignoring the dump.rdb file.
# 指定是否在每次更新操作后进行日志记录,Redis在默认情况下是异步的把数据写入磁盘,如果不开启,可能会在断电时导致一段时间内的数据丢失。
# 因为redis本身同步数据文件是按上面save条件来同步的,所以有的数据会在一段时间内只存在于内存中。默认为no
# IMPORTANT: Check the BGREWRITEAOF to check how to rewrite the append
# log file in background when it gets too big.

appendonly no

# 指定更新日志文件名,默认为appendonly.aof
# appendfilename appendonly.aof

# The fsync() call tells the Operating System to actually write data on disk
# instead to wait for more data in the output buffer. Some OS will really flush
# data on disk, some other OS will just try to do it ASAP.

# 指定更新日志条件,共有3个可选值:
# no:表示等操作系统进行数据缓存同步到磁盘(快)
# always:表示每次更新操作后手动调用fsync()将数据写到磁盘(慢,安全)
# everysec:表示每秒同步一次(折衷,默认值)

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", that in pratical terms means that it is
# possible to lost 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.
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 will growth by the specified percentage.
#
# This is how it works: Redis remembers the size of the AOF file after the
# latest rewrite (or if no rewrite 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 precentage of zero in order to disable the automatic AOF
# rewrite feature.

auto-aof-rewrite-percentage 100
auto-aof-rewrite-min-size 64mb

################################## SLOW LOG ###################################

# The Redis Slow Log is a system to log queries that exceeded a specified
# execution time. The execution time does not include the I/O operations
# like talking with the client, sending the reply and so forth,
# but just the time needed to actually execute the command (this is the only
# stage of command execution where the thread is blocked and can not serve
# other requests in the meantime).
#
# You can configure the slow log with two parameters: one tells Redis
# what is the execution time, in microseconds, to exceed in order for the
# command to get logged, and the other parameter is the length of the
# slow log. When a new command is logged the oldest one is removed from the
# queue of logged commands.

# The following time is expressed in microseconds, so 1000000 is equivalent
# to one second. Note that a negative number disables the slow log, while
# a value of zero forces the logging of every command.
slowlog-log-slower-than 10000

# There is no limit to this length. Just be aware that it will consume memory.
# You can reclaim memory used by the slow log with SLOWLOG RESET.
slowlog-max-len 1024

################################ VIRTUAL MEMORY ###############################

### WARNING! Virtual Memory is deprecated in Redis 2.4
### The use of Virtual Memory is strongly discouraged.

### WARNING! Virtual Memory is deprecated in Redis 2.4
### The use of Virtual Memory is strongly discouraged.

# Virtual Memory allows Redis to work with datasets bigger than the actual
# amount of RAM needed to hold the whole dataset in memory.
# In order to do so very used keys are taken in memory while the other keys
# are swapped into a swap file, similarly to what operating systems do
# with memory pages.
# 指定是否启用虚拟内存机制,默认值为no,
# VM机制将数据分页存放,由Redis将访问量较少的页即冷数据swap到磁盘上,访问多的页面由磁盘自动换出到内存中
# 把vm-enabled设置为yes,根据需要设置好接下来的三个VM参数,就可以启动VM了
vm-enabled no
# vm-enabled yes

# This is the path of the Redis swap file. As you can guess, swap files
# can't be shared by different Redis instances, so make sure to use a swap
# file for every redis process you are running. Redis will complain if the
# swap file is already in use.
#
# Redis交换文件最好的存储是SSD(固态硬盘)
# 虚拟内存文件路径,默认值为/tmp/redis.swap,不可多个Redis实例共享
# *** WARNING *** if you are using a shared hosting the default of putting
# the swap file under /tmp is not secure. Create a dir with access granted
# only to Redis user and configure Redis to create the swap file there.
vm-swap-file /tmp/redis.swap

# With vm-max-memory 0 the system will swap everything it can. Not a good
# default, just specify the max amount of RAM you can in bytes, but it's
# better to leave some margin. For instance specify an amount of RAM
# that's more or less between 60 and 80% of your free RAM.
# 将所有大于vm-max-memory的数据存入虚拟内存,无论vm-max-memory设置多少,所有索引数据都是内存存储的(Redis的索引数据就是keys)
# 也就是说当vm-max-memory设置为0的时候,其实是所有value都存在于磁盘。默认值为0
vm-max-memory 0

# Redis swap文件分成了很多的page,一个对象可以保存在多个page上面,但一个page上不能被多个对象共享,vm-page-size是要根据存储的数据大小来设定的。
# 建议如果存储很多小对象,page大小最后设置为32或64bytes;如果存储很大的对象,则可以使用更大的page,如果不确定,就使用默认值
vm-page-size 32

# 设置swap文件中的page数量由于页表(一种表示页面空闲或使用的bitmap)是存放在内存中的,在磁盘上每8个pages将消耗1byte的内存
# swap空间总容量为 vm-page-size * vm-pages
#
# With the default of 32-bytes memory pages and 134217728 pages Redis will
# use a 4 GB swap file, that will use 16 MB of RAM for the page table.
#
# It's better to use the smallest acceptable value for your application,
# but the default is large in order to work in most conditions.
vm-pages 134217728

# Max number of VM I/O threads running at the same time.
# This threads are used to read/write data from/to swap file, since they
# also encode and decode objects from disk to memory or the reverse, a bigger
# number of threads can help with big objects even if they can't help with
# I/O itself as the physical device may not be able to couple with many
# reads/writes operations at the same time.
# 设置访问swap文件的I/O线程数,最后不要超过机器的核数,如果设置为0,那么所有对swap文件的操作都是串行的,可能会造成比较长时间的延迟,默认值为4
vm-max-threads 4

############################### ADVANCED CONFIG ###############################

# Hashes are encoded in a special way (much more memory efficient) when they
# have at max a given numer of elements, and the biggest element does not
# exceed a given threshold. You can configure this limits with the following
# configuration directives.
# 指定在超过一定的数量或者最大的元素超过某一临界值时,采用一种特殊的哈希算法
hash-max-zipmap-entries 512
hash-max-zipmap-value 64

# Similarly to hashes, small lists are also encoded in a special way in order
# to save a lot of space. The special representation is only used when
# you are under the following limits:
list-max-ziplist-entries 512
list-max-ziplist-value 64

# Sets have a special encoding in just one case: when a set is composed
# of just strings that happens to be integers in radix 10 in the range
# of 64 bit signed integers.
# The following configuration setting sets the limit in the size of the
# set in order to use this special memory saving encoding.
set-max-intset-entries 512

# Similarly to hashes and lists, sorted sets are also specially encoded in
# order to save a lot of space. This encoding is only used when the length and
# elements of a sorted set are below the following limits:
zset-max-ziplist-entries 128
zset-max-ziplist-value 64

# 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 an hash table
# that is rhashing, 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.
# 指定是否激活重置哈希,默认为开启
activerehashing yes

################################## INCLUDES ###################################

# 指定包含其他的配置文件,可以在同一主机上多个Redis实例之间使用同一份配置文件,而同时各实例又拥有自己的特定配置文件
# include /path/to/local.conf
# include /path/to/other.conf

Redis-Dump

Mac 中安装Redis-Dump

安装RVM

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$ curl -L get.rvm.io | bash -s stable
$ source ~/.bashrc
$ source ~/.bash_profile
$ rvm -v
# 列出已知ruby的版本
$ rvm list known

安装 Ryby2.2.4

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$ rvm install 2.2.4
$ ryby -v

安装 Redis-Dump

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$ gem install redis-dump

导出数据

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$ redis-dump -u ip:port -a 'password' -d 0 > redisA.json

导入数据

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$ cat redisA.json | redis-load -u 127.0.0.1:6379 -a 'pwssword'

Redis 执行 Lua

Redis执行Lua基本命令

命令 说明
EVAL 执行Lua脚本。
EVALSHA 执行Lua脚本的sha1。
SCRIPT FLUSH 清空Redis Script。
SCRIPT LOAD 将一个脚本装入脚本缓存,但并不立即运行它
SCRIPT EXISTS 根据给定的脚本校验和,检查指定的脚本是否存在于脚本缓存
SCRIPT KILL 杀死当前正在运行的脚本

Redis Lua scripts debugger

介绍

Redis 执行Lua脚本的过程

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发送命令请求
EVAL "return redis.call('DBSIZE')" 0
Caller ------------------------------------------> Redis

为脚本 "return redis.call('DBSIZE')"
创建 Lua 函数
Redis ------------------------------------------> Lua

绑定超时处理钩子
Redis ------------------------------------------> Lua

执行脚本函数
Redis ------------------------------------------> Lua

执行 redis.call('DBSIZE')
Fake Client <------------------------------------- Lua

伪客户端向服务器发送
DBSIZE 命令请求
Fake Client -------------------------------------> Redis

服务器将 DBSIZE 的结果
(Redis 回复)返回给伪客户端
Fake Client <------------------------------------- Redis

将命令回复转换为 Lua 值
并返回给 Lua 环境
Fake Client -------------------------------------> Lua

返回函数执行结果(一个 Lua 值)
Redis <------------------------------------------ Lua

将 Lua 值转换为 Redis 回复
并将该回复返回给客户端
Caller <------------------------------------------ Redis

开启调试会话

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$ redis-cli --ldb --eval /tmp/script.lua
$ redis-cli --ldb --eval /tmp/script.lua mykey somekey , arg1 arg2

LDB 在默认情况下将使用子进程来创建调试会话, 并且在调试完成之后, 脚本对数据库进行的任何修改都将会被回滚。

开启同步模式

在一些特殊情况下, 为了追踪特定的 bug , 用户可以会想要保留每个调试会话对数据库所做的修改。 想要这么做的用户可以在启动调试器时, 向 redis-cli 客户端给定 ldb-sync-mode 选项:

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$ redis-cli --ldb-sync-mode --eval /tmp/script.lua

错误处理

说明
redis.call() 当 redis.call() 在执行命令的过程中发生错误时,脚本会停止执行,并返回一个脚本错误,错误的输出信息会说明错误造成的原因。
redis.pcall() redis.pcall() 出错时并不引发(raise)错误,而是返回一个带 err 域的 Lua 表(table),用于表示错误

Redis使用Lua的注意事项

  1. 如果Lua脚本中包括全局变量时,会报错。定义变量时不要落下local关键字。
  2. 一定要确保Lua脚本已经通过load script或eval加载或执行脚本之后再调用evalsha。
  3. 在一主多从的环境中,一定要注意使用evalsha时,从服务有可能会出现未成功加载lua脚本的情况。
    redis配置文件中一定要设置lua超时钩子lua-time-limit 5000。

Redis监控

Monitor

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$ redis-cli monitor

RedisMonitor

试用了一下,就是一个空的东西,什么都没有,什么功能也没有。

安装redis-monitor 1.0.3

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$ pip install redis-monitor
$ redis-monitor init
$ redis-monitor createdb
$ redis-monitor start
$ curl http://localhost:9527

常见问题

error: jemalloc/jemalloc.h: No such file or directory

问题分析

libc 并不是默认的 分配器, 默认的是 jemalloc, 因为 jemalloc 被证明 有更少的 fragmentation problems 比libc。

解决办法

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$ make MALLOC=libc

参考

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