java performance tuning and optimization

StringBuffer's concurrent security version, performance is slightly less than stringbuider, and there is no concurrency processing problem, Therefore, it is natural to choose StringBuilder with better performance.Only three lines of code can solve the problem that I have been tossing for a while, the reason lies in the following reasons①: Preconceived ideas, always put performance problems and concurrent h

Java program performance optimization: finding out the culprit of memory overflow and java Performance Optimization I once worked on a small swing program when I first got into the line. I used

Java program performance optimization skills and java performance optimization skills 1. Optimize the loop bodyIf the number of loops is large, the problems with poor code processing in the loop body will be magnified. For (int I

Performance issues with Java EE applications are a very important issue for serious projects and products. In particular, enterprise-class applications, concurrent users, a large number of data transmission, business logic complex, occupy more system resources, so performance problems in enterprise-class applications become critical, it and the stability of the s

1 , JAVA Performance Tuning-do not use expressions in loop conditionsWhen we learn about Java Performance Tuning, we often see this passage: In the case of No compilation optimization,

monitor the connection pool found that only getting the connection did not release the connection operation, which appears to belong to 1. Due to the use of Eclipselink thought Entitymanager. Close () can release the connection, after reviewing the Eclipselink official documents, the original is improper use, the following is to obtain the connection details:Https://wiki.eclipse.org/EclipseLink/Examples/JPA/EMAPIJPA 2.0= Entitymanager.unwrap (java.sql.Connection. Class);... entitymanager.gettr

, the most important of which is how long the thread has been running. Consider this factor to allow each thread to get the chance to run. So, regardless of how low the priority of the thread is set, they always get the chance to run.In addition, the weight of the thread priority set on the different OS is different. On Unix-based systems, the execution time of a thread is a factor in the current priority of the dominant thread, which means that the thread priority set is rarely "referenced". On

Recreate the classic, uncover the face of the pseudo-tall, easy to handle jvm!1. JVM base (selection, memory model, GC, etc.)2. JVM Key Parameters3. JVM monitoring (commands, tools)4. Typical JVM performance issues (CPU, memory leak, thread lock, etc.)Address: http://edu.51cto.com/course/course_id-4868.htmlPS: with Tomcat video betterAddress: http://edu.51cto.com/course/course_id-4166.html"Video" Java JVM

1 , JAVA Performance Tuning-Move the Try/catch block out of the loopIt is said that the Try/catch block into the circulation body, will greatly affect performance. The use of the Try/catch module makes the Java virtual machine do a lot of extra work. It's like saying to ever

1234 [ ~]# cat gc.log.0 | grep ‘Full GC‘1.652: [Full GC (System) 1.652: [CMS: 0K->21718K(262144K), 0.0837910 secs] 48398K->21718K(458752K), [CMS Perm : 16462K->16457K(21248K)], 0.0841650 secs] [Times: user=0.08 sys=0.00, real=0.08 secs] 664643.879: [GC 664643.879: [ParNew: 134434K->3202K(196608K), 0.0068030 secs] 327839K->196659K(458752K) icms_dc=0 , 0.0070080 secs] [Times: user=0.03 sys=0.00, real=0.01 secs] 1.625, 664643.879 is the time that the GC occurred, the number of seconds

this area is mainly for the recovery of constant pool and unloading of type, in general, the recovery of this area "score" is very difficult to be satisfactory, especially the type of unloading, the condition is very harsh, but this part of the area of the recovery is really necessary.　　Instead, run a constant pool as part of the method area. class file In addition to the class version, fields, methods, interfaces, and other descriptive information, there is also a constant pool, for the compil

process-verify 00:10:24 minutesSection 90th class loading process-ready 00:05:40 minutes91st class loading process-parsing 00:14:04 minutesSection 92nd Class loading procedure-initialize 00:19:41 minutes93rd class loader 00:22:41 min94th Session Parent delegation Model 00:17:03 min95th Section Runtime stack frame structure 00:08:46 minSection 96th Local Variables table 00:20:48 min97th Operation Stack 00:08:36 min98th Session dynamic Connection 00:02:56 min99th section method return address and

** Copyright 2006 ATPCO Confidential and proprietary. All rights Reserved.*/Package com.zcd.test;Import Java.sql.Timestamp;public class Test {private int x;private static int staticx;public void stackaccess (int val) {int j = 0;for (int i = 0; i j + = 1;}}public void instanceaccess (int val) {int tempx=x;for (int i = 0; i TEMPX + = 1;}}public void staticaccess (int val) {int tempx=staticx;for (int i = 0; i TEMPX + = 1;}}public static void Main (string[] args) {System.out.println (New Timestamp (

1. Introduction:Javamelody can monitor Java or Java EE application servers in a running environment. It is displayed as a graph: Java memory and Java CPU usage, number of user sessions, JDBC connections, and HTTP requests, SQL requests, JSP pages and Business interface methods (EJB3, Spring, Guice), average execution t