Articles
Advanced Java

Analysis and optimization of too long message transmission between storm1.0 nodes

Preface: The performance test of the storm platform system recently found that occasionally oncebolt sends data to another twobolt, and it takes 500 milliseconds for twobolt to receive it for processing. Here, simply increasing the parallelism of twobolt can be solved, but the internal reason is the problem caused by the communication mechanism of storm. First introduce the background: the structure of a topology, spout (parallelism: 1) [processing performance: capacity 0.04], oncebolt (paralle

... Greyson
schedule 6 min read
Advanced Java

Redis persistence quick recall manual

The persistence mechanism provided by Redis:  1). RDB persistence: This mechanism refers to writing snapshots of data sets in memory to disk within a specified time interval.   2). AOF persistence: This mechanism will record every write operation processed by the server in the form of a log. The file will be read at the beginning of the Redis server to rebuild the database to ensure that the data in the database is complete after startup of.   3). No persistence: We can disable th

... Ashton
schedule 6 min read
Advanced Java

Strom serialization mechanism

Tuples in Storm can contain any type of object. Because Storm is a distributed system, Storm must know how to serialize and deserialize message objects when passing messages between different tasks. Storm uses the Kryo library to serialize objects. Kryo is a flexible and fast serialization library. Storm supports serialization of basic types, string, byte arrays, ArrayList, HashMap, HashSet, and Clojure's collection types by default. If you need to use other object types in the tuple, you need

... Kaden
schedule 9 min read
Advanced Java

In a word, clear distributed locks, process locks, thread locks

In the development of distributed cluster systems, thread locks often cannot support the use of all scenarios, and new technical solutions for distributed locks must be introduced.Thread lock, process lock, distributed lock Thread lock: Everyone is familiar with it. It is mainly used to lock methods and code blocks. When a method or code block uses a lock, at most only one thread is executing the code at the same time. When multiple threads access the locking method/code block of the same objec

... Hunter
schedule 10 min read
Advanced Java

Spring common annotation usage analysis

Spring does not adopt a strategy that is better than configuration. Spring requires that the Java files in the specified path be displayed. Spring will register all appropriate java classes as spring beans.Question: How does spring know which Java classes to deal with in the original bean class?This requires the use of annotations. Spring uses some special annotations to annotate bean classes.@Component: Standard an ordinary spring Bean class.@Controller: Annotate a controller component class.@S

... Kai
schedule 5 min read
Advanced Java

Storm from entry to giving up (3), giving up the use of StreamId features

Preface: StreamId is an important feature for implementing DAG directed acyclic graphs in storm, but from the actual production environment, this function actually affects the stability of the production environment, and our system will bring the overall service impossibility when iterating. use. StreamId is an important feature for implementing DAG directed acyclic graphs in Storm. The official also provides corresponding interface implementations to allow developers to flexibly construct thei

... Justin
schedule 7 min read
Core Java

How to perform API testing of microservices

As an architecture for building complex systems, microservices have gained huge appeal in the development community. Although people are beginning to understand that it is not a panacea for all application architecture problems, applications that share the challenges related to dependencies and scaling can benefit a lot from it.The adoption rate of microservices is rising, but the struggle related to understanding how to test microservices is also increasing. Toby Clemson from ThoughtWorks does

... Nathan
schedule 14 min read
Core Java

10 challenges and solutions for microservices

I am a cloud API developer and architect, and I am currently working on providing microservices based on Google GCP for large retail customers in the United States.The transition/implementation of microservices presents major challenges for the organization. Based on my exposure to microservices in production, I have identified these challenges and solutions.I wrote this article in June 2018. At present, the microservice architecture is not mature enough to completely solve all existing challeng

... Asher
schedule 4 min read
Core Java

What are the features of Java 11 that will be launched in 40 days, and how are they different from Java 9 and 10?

What are the upcoming features in Java 11 and how are they different from Java 9 and 10?Java 10 may be a newbie in the block, but now is the time to talk about Java 11. Oracle's move to a faster release cycle means that more features and capabilities are being developed at an unprecedented rate.Although we still have 6 months to release Java 11, we can already see our approach and see how we adapt. We can also understand whether we should upgrade to Java 9, 10, or whether we should wait for Java

... Vivian
schedule 7 min read
Java Back End Development

Import struts source code into eclipse

The prefabrication conditions are the same as importing the spring source code into eclipse. The steps for importing eclipse are directly given below.step:1. Download the source code of the corresponding version of struts   http://struts.apache.org/download.cgi  . What I downloaded here is struts-2.3.16-all.zip. After the download is complete, unzip it to a local directory.2. The source code of struts is managed by maven, so you need to download maven  http://maven.apache.org

... Logan
schedule 3 min read
Java Back End Development

Description of Program arguments and VM arguments in Eclipse

When running the program, we can generally configure the run configuration. For example, after the tomcat source code is imported into eclipse, we can find that its running configuration is as follows:Among them, the element of the Program arguments configuration is the string array we pass in the main method, and the VM arguments are actually the runtime environment variables we need in the program. For example, in the above figure, catalina.home is designated as the location of the project. In

... Evan
schedule 2 min read
Java Back End Development

Algorithm of Greatest Common Divisor

The principle of the algorithm: For tossing and dividing: the greatest common divisor of i and j, that is, both i and j can divide it. In other words, the number k where i is more than n times j (i = j*n + k, i.e. i% j = k) should also be a multiple of the greatest common divisor. So it can be converted into finding the greatest common divisor of k and j. In the same way, for the more subtraction technique, the same reason, the part where i is greater than j is also a multiple of the greatest co

... Thomas
schedule 4 min read
Java Back End Development

Getting started with Jetty

OverviewLike tomcat, jetty is also a servlet engine. The magic of jetty is that jetty can not only be used as a container for a web application, it can even be used as a plug-in in a program to load the web application itself through the main function.Jetty is a Web server/servlet container that supports SPDY, WebSocket, OSGi, JMX, JNDI, JAAS. Jetty is very efficient and flexible. Google App Engine chose Jetty instead of Tomcat or other servers.Jetty has a slogan, "Don't deploy your application

... Alyssa
schedule 8 min read
Java Back End Development

Mysql lock preliminary

Storage engineTo understand mysql locks, we must start with the storage engine.The list of commonly used storage engines is shown in the figure below:The two most commonly used storage engines:Myisam is the default storage engine of Mysql. When create creates a new table, when the storage engine of the new table is not specified, Myisam is used by default. Each MyISAM is stored as three files on the disk. The file name is the same as the table name, and the extensions are .frm (storage table def

... Hudson
schedule 6 min read
Java Back End Development

In-depth study of java serialization and deserialization

When---When do you need to serialize and deserialize:Simply write a hello world program without serialization and deserialization. Writing a sorting algorithm does not require serialization and deserialization. But when you want to persist an object into a file, or you want to send an object from one network address to another network address through a network protocol, then you need to consider serialization and deserialization. In addition, if you want to make a deep copy of an object instance

... Evan
schedule 14 min read
Java Web Development

hadoop-3.2.0------>Introduction Fourteen Completely Distributed Timing Task

Service management Restart the service:service crond restartScheduled task settings 1. Basic syntax crontab[options] 2. Option description OptionsDescription-eEdit crontab timing tasks-lQuery crontab timing tasks-rDelete all crontab timing tasks of the current user 3. Parameter description Command: crontab -e: 1. Enter the crontab editing interface * * * * * Tasks performedprojectmeaningrangeFirst"*"The first few minutes of the day0-59the second"*"Hour of the day0-23The third"*"The day of the mo

... Serenity
schedule 2 min read
Java Web Development

hadoop-3.2.0------>Getting Started Thirteen Fully Distributed Clusters

Configure hadoop cluster startup script 1. Enter etc/hadoop in the root directory of hadoop 2. vi workers (after 3.0) vi salves (after 2.0) Note: The version after 3.0 is to modify the workers, the version of 2.0 is to modify the salves 3. Distribute to other nodes xync workers 4. Start dfs (start on hadoop01) sbin/start-dfs.sh 5. The startup error is as follows 6. In the /sbin path of the hadoop root directory: Add the following parameters to the top of the start-dfs.sh and stop-dfs.sh files co

... Grayson
schedule 2 min read
Java Web Development

Springboot integrated mybatis+jsp project structure: pom configuration file If you want to put the mapper file and dao layer together as shown below: modify the configuration file to

Project structure: pom configuration file <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.1.RELEASE</version> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!--jsp page use jstl tag--> <dependency> <groupId>javax.servlet&lt

... Natalie
schedule 3 min read
Java Web Development

Java time conversion

package com.example.administrator.huijianzhi.util; import android.annotation.SuppressLint; import com.example.administrator.huijianzhi.util.constant.TimeConstants; import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; import java.util.Locale; /** */ public final class TimeUtils { @SuppressLint("SimpleDateFormat") private static final DateFormat DEFAULT_FORMAT = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")

... Justin
schedule 36 min read
Java Web Development

jquery timestamp converted to date

1. Convert to year, month, and daynew Date(data.createDate).toLocaleDateString()//Convert the timestamp in json to year, month and day2. Accurate to the second function getMyDate(str){ var oDate = new Date(str), oYear = oDate.getFullYear(), oMonth = oDate.getMonth()+1, oDay = oDate.getDate(), oHour = oDate.getHours(), oMin = oDate.getMinutes(), oSen = oDate.getSeconds(), oTime = oYear +'-'+ getzf(oMonth) +'-'+ getzf(oDay) +''+ getzf(oHour) +':'+ getzf(oMin) +':'+getzf(oSen);// Last stitching tim

... Camden
schedule 2 min read
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