• Memory structure of Oracle Database


    First, we can understand the memory structure of Oracle database through a picture, as follows: Each database instance has two associated memory structures – system global area (SGA) and program global area (PGA). System global(SGA): a set of shared memory structures (called SGA components), which contain the data and control information of an Oracle DB […]

  • Memory knowledge Java programmers must know – operating system layer


    1. Virtual storage Effect 1. To provide a consistent address space for each process (starting from 0) and facilitate memory management.2. Protect the data of each process from being damaged by other processes.For the above reasons, with virtual memory, virtual memory is a file on the hard disk. For example, when we apply for 20g […]

  • Using experience of redis


    1、 What is caching used for in the system? A small amount of data storage, high-speed read-write access. The high-speed access is ensured by the way of all data in-mole, and the function of data landing is provided at the same time. In fact, this is the main application scenario of redis. Massive data storage, […]

  • Memory system


    Original link: http://kasheemlew.github.io/2 Basic concepts Memory capacity:Depending on the addressing mode, 16 bit can generate 16 bit address, so it can address in 2 ^ 16 = 64K memory units. Similarly, 32-bit can use memory containing 4G units. Mar (memory address register) and MDR (memory data register):Through these two registers, the data transmission between the […]

  • Different write modes of reduced de duplicated VDO volumes


    You can configure the write mode of VDO volume according to the requirements of low-level block devices. By default, VDO volume is automatically selected Write mode of VDO volume Sync modeWhen VDO is in sync mode, the upper layer thinks that the write command writes data to the persistent storage. The result is that the […]

  • A detailed explanation of various caches commonly used in Web Applications


    In this paper, nginx, rails, MySQL and redis are used as examples, and other web servers, languages, databases and caching services are similar.The following is the schematic diagram of the third floor for subsequent reference: 1. Client cache A client often accesses the same resource, such as using a browser to visit the homepage of […]

  • Analyze the application of cache in Ruby China


    First of all, let me show you the report of newrelic Average response time in the last 24 hours Those pages with high traffic (action) Several actions of traffic: TopicsController#show Userscontroller ා show (worse, mainly because GitHub API requests are slow) PS: before publishing this article, I slightly modified it. The GitHub request is put […]

  • Asp.net core caching static resource example details


    background Caching static resources such as stylesheets, JavaScript, or image files can improve the performance of your site. On the client side, a static file is always loaded from the cache, which can reduce the number of requests to the server, thus reducing the time to get the page and its resources. On the server […]

  • Installation and configuration of varnish cache server under Linux


    Varnish is a high performance and open source reverse proxy server and HTTP accelerator. Compared with the traditional squid, varnish has many advantages such as higher performance, faster speed and more convenient management. Poul Henning Kamp is one of the kernel developers of FreeBSD. With a new software architecture, varnish works closely with today’s hardware […]

  • Decide whether to cache HTTP requests according to the key and URL of JWT


    Link https://stackoverflow.com/que demand Decide whether to cache HTTP requests according to the key and URL of JWT For example, in JWT. payload: { “iss”: “iss”, “sub”: “sub”, “userGroupID”: “{userGroupID}” } Then request https://myapi.example.com/group… {groupid} / cars If usergroupid is the same as groupid, it will be cached, otherwise it will not be cached Solution Using […]

  • Distributed system focus — 360 ° comprehensive interpretation of “cache”


    If this is the second time to see my article, welcomeEnd scan subscriptionMy personal public number (cross border architect) yo!The length of this paper is3578Words, recommended reading10Minute.Adhere to the original, every article is the work of the heart ~ This is the first chapter of the high performance chapter. As long as a serious programmer […]

  • Redis integrates spring and uses cache instances


    1、 About redis What is redis? Redis is a key value storage system. Similar to memcached, it supports more value types, including string, list, set, Zset and hash. These data types support push / pop, add / remove, intersection, union, difference, and richer operations, all of which are atomic. On this basis, redis supports various […]