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How Redis distributed lock prevents cache breakdown

How Redis distributed lock prevents cache breakdown

The difference between cache penetration and cache penetration is that cache penetration refers to hot data that is not in the cache but exists in the database. For example: hot news on the homepage, hot data with a very large number of concurrent visits, if the cache expires and becomes invalid, the server will query the DB. At this time, if a large number of concurrent queries are made to the DB, the DB may be overwhelmed instantly. I drew a simple diagram, as shown below: Solution: DB query plus distributed lock. Before solving the problem without locking, let's take a look at the code and operation status of the unprocessed code. The product details query code based on the product ID clears the Redis cache, and opens 5 threads for concurrent access testing. The test code is as follows: We expect that the DB will only be queried once, and the next 4 queries will be fetched from the Redis cache, but the result is:

Jun 03, 2023 pm 07:04 PM
redis
How to use redis+python as a message queue

How to use redis+python as a message queue

1. Use the List type of redis combined with lpush and brpop to implement the introduction. First, the List of redis is equivalent to a queue, which can implement the first-in-first-out rule. brpop is used because when there is nothing in the queue, it will block until there is something in the queue that can be popped. Element or wait timeout simulation problem: too many accesses, the server processing speed is too slow, if the server feedback every time the user waits, the time is too long, the http connection times out, and a server error occurs. Simulation implementation process: There is a client that continuously puts things (data) into the queue, using multi-threading to simulate a large number of user access situations. There is a server that continuously takes out prints from the queue, and sets the redis sleep time of 2 seconds for each print time. Lis

Jun 03, 2023 pm 06:24 PM
python redis
How to implement redis distributed lock in python

How to implement redis distributed lock in python

1importtime2importredis3fromredis.exceptionsimportWatchError456classRedisUtil():7def__init__(self):8self.redis=redis.Redis(host="redis account url",9port=6379,10password="your redis password",11decode_responses=True)12self.online_set_name="pa

Jun 03, 2023 pm 06:22 PM
python redis
How SpringBoot uses AOP+Redis to prevent repeated submission of forms

How SpringBoot uses AOP+Redis to prevent repeated submission of forms

Configure Redis1. Add Redis dependency org.springframework.bootspring-boot-starter-data-redis2. Add redis configuration information redis:host:127.0.0.1port:6379database:0password: #Connection timeout timeout:10s Configure AOP1. Custom annotations /***Annotations to prevent repeated submission of forms*/@Target(ElementType.METHOD)//The annotation targets the method @Retention(RetentionPolicy.RUNTI

Jun 03, 2023 pm 06:10 PM
redis aop springboot
How does Java SpringBoot operate Redis?

How does Java SpringBoot operate Redis?

Redis1. Add redis dependency. springBoot provides a component package for Redis integration: spring-boot-starter-data-redis, which depends on spring-data-redis and lettuce. In addition, there are two small details here: in the SpringBoot1.x era, the bottom layer of spring-data-redis used Jedis; in the 2.x era, it was replaced by Lettuce. Lettuce depends on commons-pool2org.springframework.bootspring-boot-starter-data-r

Jun 03, 2023 pm 06:01 PM
java redis springboot
How to solve Redis cache problem

How to solve Redis cache problem

LevelDB is coming! It is Google's open source NOSQL storage engine library and an atomic bomb in the field of modern distributed storage. Based on it, Facebook developed another NOSQL storage engine library, RocksDB, which follows LevelDB's advanced technical architecture and also solves some shortcomings of LevelDB. You can compare RocksDB to a hydrogen bomb, which is more powerful than LevelDB. Many databases in the modern open source market use RocksDB as the underlying storage engine, such as the famous TiDB. But why should I talk about LevelDB instead of RocksDB? The reason is that LevelDB’s technical architecture has changed

Jun 03, 2023 pm 05:56 PM
redis
How to use AOP+redis+lua for current limiting

How to use AOP+redis+lua for current limiting

The company needs to use the OneByOne method to delete data. In order to prevent too much data from being deleted within a period of time, let me make an interface current limit here. When it exceeds a certain threshold, an exception will be reported and the deletion operation will be terminated. The implementation method is to create a custom annotation @limit to allow users to configure count (the maximum number of visits within a certain period of time) and period (a given time range), that is, the frequency of access, where needed. Then intercept the method request through LimitInterceptor, and control the access frequency through redis+lua script. The source code Limit annotation is used to configure the access frequency count and periodimportjavax.validation.co of the method.

Jun 03, 2023 pm 05:43 PM
redis lua aop
How to determine if Redis has performance problems and how to solve them

How to determine if Redis has performance problems and how to solve them

Redis is usually an important component in our business system, such as cache, account login information, rankings, etc. Once the Redis request delay increases, it may cause an "avalanche" of the business system. I work for a single matchmaker-type Internet company, and during Double Eleven, I launched a campaign to give my girlfriend a gift when I place an order. Who would have thought that after 12 o'clock in the morning, the number of users increased sharply, and there was a technical glitch that prevented users from placing orders. At that time, the old fire broke out! After searching, it was found that Redis reported Couldnotgetaresourcefromthepool. No connection resources can be obtained, and the number of single Redis connections in the cluster is very high. A large amount of traffic goes directly to MySQL without the cached response of Redis.

Jun 03, 2023 pm 05:16 PM
redis
How to clear Redis cache using command line

How to clear Redis cache using command line

1. Open the command line window and open "redis-li.exe" in the Redis installation directory. 2. Authorization. Direct operation in the opened command line will prompt that there is no permission. You need to use the auth command to authorize first. The usage method is as follows. auth ‘here is the Redis password 3. Clear the cache There are two ways to clear the cache: clear the database cache and clear all caches. 1. Clear the database cache: flushdb2. Clear all caches: flushall

Jun 03, 2023 pm 04:34 PM
redis
How to use Redis cache elimination strategy and transactions to implement optimistic locking

How to use Redis cache elimination strategy and transactions to implement optimistic locking

Cache elimination strategy title LRU principle The LRU (Least recently used, least recently used) algorithm eliminates data based on the historical access records of the data. Its core idea is "if the data has been accessed recently, the probability of being accessed in the future is also higher." The most common implementation is to use a linked list to save cached data. The detailed algorithm is implemented as follows: new data is inserted into the head of the linked list; whenever the cache hits (that is, the cached data is accessed), the data is moved to the head of the linked list; when the linked list is full time, discard the data at the end of the linked list. In Java, you can use LinkHashMap to implement LRU using hash linked lists: Title Redis cache elimination strategy sets the maximum cache in redis, allowing users

Jun 03, 2023 pm 04:05 PM
redis
How to check Redis status in Linux system

How to check Redis status in Linux system

makemakePREFIX=/usr/local/redisinstallmkdir/etc/redis/cpredis.conf/etc/redis/Open the redis.conf file and modify daemonizeyes to run vim/etc/redis/redis.conf in the background and use the configuration file to start the redis service./ redis-server/etc/redis/redis.conf How to check that the redis service starts normally? Use ps to view or netstatpsaux|grepredis-servernetstat-tunp

Jun 03, 2023 pm 03:49 PM
linux redis
How to use Redis to solve high concurrency

How to use Redis to solve high concurrency

Short for NoSQLNotOnlySQL. NoSQL was proposed to solve the inability of traditional RDBMS to deal with certain problems. That is, non-relational databases, they do not guarantee the ACID characteristics of relational data, and there is generally no correlation between data. They are very easy to implement in terms of expansion and have high performance. Redisredis is a typical representative of NoSQL and is also a must-use technology for current Internet companies. Redis is a key-value (Key-Value) storage database, which mainly uses hash tables. Most of the time, it is used directly in the form of cache, so that the request does not directly access the disk, so the efficiency is very good, and it can fully meet the needs of small and medium-sized enterprises. Common data type characters

Jun 03, 2023 pm 03:43 PM
redis
How to implement Redis coupon flash sale function

How to implement Redis coupon flash sale function

1. Global unique ID 1. Global ID generator Each store can issue coupons: when a user rushes to buy, an order will be generated and saved in the tb_voucher_order table. However, if the order table uses the database to automatically increment the ID, there will be some problems: id The regularity is too obvious and is limited by the amount of data in a single table, so the primary key of the tb_voucher_order table cannot use auto-increment ID: createtabletb_voucher_order(idbigintnotnullcomment'primarykey'primarykey,user_idbigintunsignednotnullco

Jun 03, 2023 pm 03:39 PM
redis
What is the SpringSecurity+Redis authentication process?

What is the SpringSecurity+Redis authentication process?

The preface introduces the popular technology stack combination for permission management on the market today, which is ssm+shrioSpringCloud+SpringBoot+SpringSecurity. This combination naturally has its own characteristics. Due to the automatic injection configuration principle of SpringBoot, SpringSecurity is automatically injected and managed when the project is created. The filter container (DelegatingFilterProxy), and this filter is the core of the entire SpringSercurity. Masters the entire permission authentication process of SpringSercurity, and SpringBoot helps you automatically inject it, and use ssm to complete it.

Jun 03, 2023 pm 03:22 PM
redis springsecurity

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