java application performance tuning interview questions

For most application development, microsecond optimizations are usually ignored or not, because there are more optimizations, but for the common libraries that are used to develop the provisioning system, most of the operations are usually on characters, numbers, strings, and bytes, and these system libraries are often called very frequently, For example, for a middleware, a single RPC request might involve hundreds or thousands of operations, so fine

Java Collection related interview questions and answers Interview questions1.JavaWhat is a collection frame? What are some of the advantages of a collection framework? There are collections in each programming language, and the original Java version contains several collect

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. 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 metho

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

integer.In other words, a mutex can only be used for mutually exclusive access to a resource, and it cannot implement multi-threaded mutex issues for multiple resources.The semaphore can realize multi-thread mutual exclusion and synchronization of multiple homogeneous resources.When the semaphore is a single-valued semaphore, it is also possible to complete mutually exclusive access to a resource.3. The lock and unlock of the mutex must be used by the same thread, the semaphore can be freed by

First, let's talk about the differences among final, finally, and finalize. Second, can Anonymous Inner Class (Anonymous internal Class) be extends (inherited) other classes, or implements (implemented) interface (interface )? Third, the difference between Static Nested Class and Inner Class is that the more you say, the better (the more general the interview questions are ). Fourth, the difference between

rewrite the aof file, the performance impact of this persistence is minimal, but the aof file will continue to grow, aof file over the General Assembly to affect the recovery speed of master restart. Master should not do any persistent work, including memory snapshots and aof log files, in particular, do not enable memory snapshots to persist, if the data is more critical, a slave open aof backup data, the policy is synchronized once per second.

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

inherit it. Subclass overwrites the finalize () method to sort system resources or perform other cleanup tasks. The finalize () method is called before the Garbage Collector deletes an object. Second, can anonymous inner class (anonymous internal class) be extends (inherited) other classes, or implements (implemented) interface (Interface )? An anonymous internal class is an internal class without a name. It cannot be extends (inherited) other classes, but an internal class can be used as an in

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

threads are not able to modify objects in the collection that is being traversed by iterator. At the same time, iterator allows the caller to delete elements from the underlying collection, which is not possible for enumeration.What is the difference between 17.HashSet and TreeSet?HashSet is implemented by a hash table, so its elements are unordered. The time complexity of the add (), remove (), contains () method is O (1).On the other hand, TreeSet is implemented by a tree-shaped structure in

XML interview questions include XSLT techniques for transforming XML files, xpath,xquery, and XML basics such as DTDs or schemas. This article will see 10 common XML interview questions and answers. Most of these questions are asked in a

Analysis and Summary of Baidu Java R D interview questions 1. Analysis of Common application scenarios in singleton mode. Among the 23 design modes, the singleton mode is the largest. It is easy to understand, but applicable to scenarios. Are you really familiar with this? The use of Singleton is because there is no

Java and C common technical interview questions 2015 (Continuous updates ...), 2015 updating 1. Differences between overwrite and overload Overload is an Overload. It uses the same name as an existing member to declare attributes or methods, but the parameter list is different from that of the original member. Override is mainly used for method rewriting between

Java programmer interview questions (86-115) 86. In Struts 2, how does Action obtain the data that the user inputs from the page, and how does it transmit its own data to the view? A: There are three ways for Action to retrieve data from the page: 1) accept parameters through the Action attribute 2) obtain parameters through the domain model 3) ModelDriven )

Java interview question Summary 2 (Continuous updates), java questions 1. How to format a date Answer:Date now = new Date (); SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd hh: mm: ss "); String formatNow = sdf. format (now ); The formatNow variable is the formatted date. 2. What are several implementation m

Java Multithreaded interview questions 1. What is the difference between processes and threads? A process is a stand-alone (self contained) operating environment that can be viewed as a program or an application. A thread is a task that is performed in a process. The Java

After JDK5, Java provides a more convenient security mechanism that uses lock locks for thread-locked operations and release operations without using synchronized . More clear. Example:Lock lock=new Reentrantlock ();Lock.lockCode that needs to be lockedLock.unlockWhy is lock more secure? Because synchronized may cause deadlock phenomenon, specifically about the deadlock phenomenon can refer to the operating system, there is no more to say.Summarize th

** 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 (