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owns the lock gets the lock again, then the fetch counter increases by 1, and then the lock needs to be freed two times to get a true release. This mimics the semantics of synchronized; If a thread enters a synchronized block that is protected by a monitor that the thread already owns, it allows the thread to continue and does not release the lock when the thread exits the second (or subsequent) synchronized block. The lock is released only when the thread exits the first synchronized block tha

overwhelmed; then there is the vertical partitioning of data, the vertical partitioning of data is to write more frequent data tables, such as user table _user, or Order table _orders, then we can separate this two table, put on a different server, if the two tables and other tables exist in the table query, then only the original SQL statement to split, first query a table, in the query another, although this will consume more performance, but compared to the kind of large data synchronization

Hibernate project, it is the object that you encounter when you start hibernate.Benefits of HibernateHibernate handles mapped Java classes to use XML files, database tables, and no need to write any line of code.Provides a simple API for storing and retrieving Java objects directly from a database.If there is a change in the database or in any table then only the properties of the XML file need to be modified.Abstract out unfamiliar SQL types and provide us with a familiar Java object to solve.

],ri[100010];//FAILDFN is the DFS order on the fail tree, and Le and RI are the left and right intervals of a node on a tree arrayvoidGET_FAIL_DFN (intu) {intI,V;FAILDFN[U]=++FAILCLK;LE[U]=FAILCLK; for(I=first[u];~i;i=e[i].next) {v=e[i].to; GET_FAIL_DFN (v); } RI[U]=FAILCLK;}intMain () {scanf ("%s", s);intI,j,x,y,xx; Add (s); GETDFN (0); Getfail (); GET_FAIL_DFN (0); scanf"%d", q); for(i=1; i"%d%d", qq[i].x,qq[i].y), qq[i].num=i; Sort (QQ+1, Qq+q+1, CMP);//Sortj=1; for(i=1; i while(Now

operating system (OS) settings. There are several tools for developers to use when analyzing and optimizing, and you can learn and use them by reading Java tools for Source Code optimization and analyses.It is important to understand that no two applications can use the same optimizations, and there is no perfect reference path for optimizing Java applications. Use best practices and stick with the right way to handle performance optimizations. To achieve true maximum performance optimization,

of reflection, how to optimize?Definition of reflection mechanism:is in the running state, for any one class, can know all the properties and methods of this class, any object can be invoked through the reflection mechanism of a class of any method, the dynamic acquisition of class information and the function of dynamic call class object method is called Java reflection mechanism.The effect of reflection:1. Dynamically create an instance of the class, bind the class to an existing object, or g

who want to learn these techniques can add a group: 650385180. The group will share these technical knowledge points for everyone to learn to download for free. We hope to help you to build your own technical system and technical knowledge in a comprehensive and scientific way!Distributed Learning RoutesMicro-Service Learning routePerformance Optimization Learning routeClassic design pattern and source code analysisDeveloping the necessary toolsHands-on projectsSummarize:The above is I summed u

├──feat Ure_neg.txt #feature All negative examples ├──feature_p.npy├──trainset.npy #训练集 ├──testset.npy #测试集 └──31day_ in. txt Data_features.txt #31天所有数据的n维特征 # results ├──predict_all_pairs.txt #得到所有预测的userid itemid to └──filter_pairs.txt #用train_item过 Filter the UserID itemid to PrincipleThe topic gave 31 days of data, and we chose the 30th day as the dividing point. Extract the n-dimensional features from the first 30 days of data (each [user_id,item_id] pair can fetch a single line of features

subscript first move, and record the current temporary maximum value of the underlying (such as I first move, record I_max), when encountered a new maximum value of the time , not only to the I to the local variable zeroing, but also to compare the maximum value and J corresponding value of the size relationship, and then the smaller value corresponding to the subscript continues to move, until the two subscript meet, traversed the array so far.Program codeintVolume (int* Height,intN) {inti =0;

=converttonulljdbc.username= Rootjdbc.password=123456initialsize=0maxactive=20maxidle=20minidle=0maxwait=10000validationquery=select 1testonborrow=falsetestonreturn=falsetestwhileidle=truetimebetweenevictionrunsmillis= 6000minevictableidletimemillis=25200000removeabandoned=trueremoveabandonedtimeout=1800logabandoned=truefilters =stat3.web.xml Add the following configuration Connection Pool Monitoring - Filter> Filter-name>DruidwebstatfilterFilter-name> Filter-class>Com.aliba

Const WX = require ('./1.3.2.js '). Wxconst plugin = { Install (Vue) { vue.prototype. $wechat = wx vue.wechat = WX }, $wechat: Wx}export default pluginexport Const INSTALL = Plugin.install/** * Created by Cuiyang on 2018/7/3. */const Alipay = require ('./alipayjsapi.min '). Apconst plugin = { intall () {vue.prototype . $alipay = Alipay Vue.alipay = Alipay }, alipay:alipay}export default pluginexport Const INSTALL = Plugin.installThe vue-plugin references

machine, then it is obvious that the two database data is not uniform problem. So in this case, we can first consider the use of read-write separation method.The database system structure after read and write separation is as follows:This structural change will also bring two problems:Synchronization of data between master and slave databasesApplication selection issues for the data sourceProblem Solving Scenarios:We can implement master-slave replication using MySQL's own master+slave.Use thir

Speaking of JSON parsing, there are many ways, whether it is from Google's Gson, or from other xxx, presumably everyone is familiar. Strolling around GitHub today, encountering a JSON parsing library, looks pretty good, and is said to be the fastest analytic josn solution available. Why the artifact, he is from the Ali team Fastjson.For the sake of convenience, refer to the following code.With Maven's classmates is more convenient, directly double-cli

"Want to head" can be more convenient to others anytime and anywhere with you, buy and sell baby, make Amoy friends! can be added anywhere on the internet, so that others know want want online status, as long as a little "contact me" business is coming, hehe. And you can add a number of Wang Wang, this shop has a number of customer service staff of the Wang Shop is very useful, the shopkeeper can set up a number of Wang Wang's customer service zone, the team is more powerful oh. This is Taobao

You can enter the menu in the upper-right corner of the Ali Wangwang, select system settings, and in the pop-up page, select "Security Settings"--prevent harassment and, if necessary, choose ' do not receive information from strangers '. Strangers refer to users who have never been contacted, and if they are sellers, use this function with caution. You can also select the "start to prevent harassment", the right Point "add", enter the information you

Ali telephone side of the afternoon, the whole journey of about 50 minutes, the other voice is very special, across the phone I can feel very serious appearance. Directly on dry goods 1. Briefly Introduce yourself 2. The difficulty of the whole project and how to solve it 3. How to ensure data consistency 4. How to optimize the database, specifically speaking 5. Hibernate caching mechanism 6. Mysql table Lock line Lock How to ensure that data does not

First, installation Online Installation Address: https://p3c.alibaba.com/plugin/eclipse/update 1. Click help–> Install New Software ...2. Click the Add button in the pop-up window, enter name (any) and location (plugin URL), click OK3. Check the contents of the plug-in, the installation can be step-by-step.Second, the use1. Scan. Item right Menu select "Ali Code protocol Scan".Scanning results are divided into three categories: Blocker (crash) Crit

Given a string, find the length of the oldest string that does not contain duplicate characters. Example: Given "ABCABCBB", the oldest string without repeated characters is "abc", then the length is 3. Given "BBBBB", the longest substring is "B", the length is 1. Given "Pwwkew", the eldest son string is "Wke", and the length is 3. Note that the answer must be a substring, and "Pwke" is a subsequence rather than a substring. In fact, this problem is very simple, but also because of their own fou

and attribute value), and information about the server (by passing a ServletContext object)1, with 1-5 working experience, in the face of the current popular technology do not know where to start, the need to break through the technical bottlenecks can add group.2, in the company for a long time, live very comfortable, but job-hopping when the interview hit the Wall. Need to study in a short time, job-hopping to get high salaries can add group.3, if there is no work experience, but the foundati

The long-awaited Ali Java Development Specification plug-in, finally released in 2017-10-14, this specification plug-in really Java developers must have tools, it is worth a praise. 1. Download and install the plugin Settings >> Plugins >> Browse repositories ... 2. Restart idea Tools >> Alibaba Coding Guidelines 3, Code analysis check list Settings >> inspections >> all-check code Check List 4, code check Right or shortcut key CTRL + Sh