High CPU Usage With Classes Loaded Skyrocketing
May 30, 2014
We have a webservices application that uses Java 1.6.0_43, Spring 3.2.3, CXF 2.6.9 and deployed to Jboss 5.0.1 GA in a LINUX x86_64 centos box. It essentially uses apache httpclient (4.2.2) to call internal services and returns the results back to customers. The application has been running fine for a year or so until early this month when all of sudden, it loaded about 300K classes in a very short time during our regression tests and saturated the CPU usage ever since. Hence the application is no longer responding.
I have been trying to troubleshoot the problem for a while. Tried visualvm, dynatrace. thread dumps. heap dumps... None of them is very effective in capturing what are the classes that are loaded so many times and what path triggered that.
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Apr 8, 2014
Since I done a recent git pull on my project, for some reason now Im getting an error when starting Tomcat and rendering the index.jsp, but I dont understand whats changed, as this was working before.
The error:
org.apache.jasper.JasperException: /index.jsp (line: 4, column: 42) File "/blog.postTags" not found
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:42)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:443)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:133)
org.apache.jasper.compiler.TagLibraryInfoImpl.<init>(TagLibraryInfoImpl.java:168)
org.apache.jasper.compiler.Parser.parseTaglibDirective(Parser.java:410)
org.apache.jasper.compiler.Parser.parseDirective(Parser.java:475)
org.apache.jasper.compiler.Parser.parseElements(Parser.java:1427)
The index.jsp:
<!DOCTYPE html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="p" uri="blog.postTags" %>
<html>
<head><title>Blog Home</title></head>
<body>
<h1>Blog Home</h1>
<br />
<% out.println("Your IP address is " + request.getRemoteAddr()); %>
[code]....
I really am unsure as to why this has stopped working, I even rolled back to an earlier commit and this was definitely working before, but I havent changed anything, Initially when you start Tomcat is shows another error in the browser, but on a refresh its a null on this tag library?
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Feb 9, 2014
I would like to know why javax.faces.webapp.FacesServlet
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Jun 23, 2014
I am creating a webapp project , in which i have loaded my JSP page having JSTL tags in a DIV tag successfully but when user clicks on a radio button a jquery fires which loads that perticular div tag , and the html content in that div tag is then loaded again but not the JSTL content..
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May 19, 2015
While loading very huge xml file i m getting heap space error in myeclipse. So I wanted how to increase memory so that xml file will get loaded?
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Nov 4, 2014
I am creating a shopping list, with each element and object called product from the Item attribute class. Each product object has a description, price, and priority. From user input, I am able to create each product object, and then .add to my arraylist. I know that it successfully adds because I have it printed in each iteration of the do-while loop. Once the user indicates they want to quit, the loop ends. I then want to print each description, price, and quantity but this for loop will only print the last element over and over. Here is what I have:
ArrayList <ItemAttribute> list = new ArrayList<ItemAttribute>();
Scanner keyboard = new Scanner(System.in);
ItemAttribute product = new ItemAttribute();
public void findDescrPrice() {
/**
* Get the item name (description) for each list item
[code]...
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Jun 18, 2014
I have one Project -"A".Inside of that I use, .XLS to read data.
Structure - A/src/TestData
Inside of the TesetData - I have placed XLS files.
I have main method in TestDriver class.If I run this in Eclipse, running fine.But after exported to executable/runnable Jar, and ran via command line (command - jar -jar myjar.jar), I see issue: "Exception in thread "main" java.io.FileNotFoundException: srcTestDataTestCaseController.xls"
public static void main(String[] args)
throws Exception
{
ResultSet rs;
rs = readExcelData(testControllerName, sheetName, "");
}
As I use main() method which is static, I am getting error if I write like the below:
public void getXls(){
String testControllerName ="TestCaseController.xls"
TestDriver.getClass().getClassLoader().getResource (testControllerName);
}
How to read/access the XLS, after I exported as runnable jar
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Sep 3, 2014
i want to make an application that use vers high numbers, but can int, double, float, or long do that for me?
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Nov 19, 2014
I am trying to write a code that asks the user to enter a temperature for each day of the week and then it prints out the high temperature, the low temperature, and the average temperature. This is the code I have so far:
import java.util.*;
import java.text.DecimalFormat;
public class Lab10 {
public static void main(String[] args) {
java.util.Scanner input = new java.util.Scanner(System.in);
int high, low, i, sum;
double avg;
[Code] ....
There are a few issues that I am having.
1. I can't for the life of me figure out how to make it print the low temperature
2. I had it running perfectly until I changed one thing and now I get a compile error saying that the last 5 statements are unreachable. (lines 32-37)
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Apr 21, 2014
This program will not give me the average high temperature for the week and I cannot figure out why! Every time it only spits out "0" whereas the average low temperature works great..
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Temps_Grid_Keenan extends JFrame
{
private static final long serialVersionUID = 1L;
private static final int WIDTH = 400;
private static final int HEIGHT = 500;
private JTextField high1Field, low1Field, high2Field, low2Field;
private JTextField high3Field, low3Field, high4Field, low4Field;
private JTextField high5Field, low5Field, high6Field, low6Field;
private JTextField high7Field, low7Field, ave_highField, ave_lowField;
[code]....
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Apr 7, 2014
I want to get current Computer CPU usage of my computer and display it in Console View of Eclipse? How can I achieve this?
My template code is:
Java Code: public class GetCPUUsage{
public static void main(String[] args){
System.out.println("CPU USAGE IS: ??????");
}
} mh_sh_highlight_all('java');
I added ??? as placeholder for CPU usage because I do not know how to retrieve RAM usage by Java.
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Aug 28, 2014
I am trying to figure out how to report the high and low scores with names from a file. The format is like:
6352 J@me$$
663843 BOBBBB1
etc...
This is my code so far.
import java.io.*;
import java.util.*;
public class Assignment1
{
public static void main(String[] args)throws IOException
[code]....
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Jul 17, 2014
I have a class as shown below. This class has a method addFilter with 2 parameters (type String and type Command1 )
public class Command1 {
public StringBuffer addFilter(String query, Command1 dataBase) {
//concrete implementation
return query;
}
}
I have another class Command2. Here I need a similar method. The only difference is in the type of parameters passed. (type String and type Command).
public class Command2 {
//TO DO:
public StringBuffer addFilter(String query, Command2 cmd) {
//concrete implementation
return query;
}
}
I have started by using Interface
public interface Helper {
public StringBuffer addFilter(String query, XXXXX parameter2);
}
I would like the classes Command1 and Command2 to implement the interface Helper and override it these two public classes.
However my problem is in dealing with the 2nd parameter. Am I right in my approach? How do I handle this issue?
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Sep 16, 2014
I am trying to code a program that orders 5 random numbers from high to low with the basic coding i know (im starting to learn theory of methods... so you can imagine) When i run the code i cant get all 5 numbers ordered but my logic says the code is right although it's pretty confusing.
I know you could code in a simpler way but first i wanna get it as it is right now. When i debug (on my own way cause i dont know how to actually use it) shows line 72 with yellow color.
public class NuevaCalculadora {
import java.util.Scanner;
public static void main(String[] args) {
[Code]....
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Jun 6, 2015
I'm trying to follow the Scene Builder tutorials on a 3200 X 1800 screen which makes the size of the content pane 3'' x 2" ....
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Aug 16, 2012
I created an instant messenger using java. When I have the Server that communicates between the clients and one client running on my Computer the CPU Usage is at 100%. It really slows down everything else I'm doing and I figure this might be an issue if I gave this to people to use. I don't want the client taking up a lot of CPU Usage if they're just running it in the background while doing other things on their computer. The program utilizes multithreading. Each thread is constantly being polled for input.
The Server, as seen below, has two threads. I explain what the threads do before the code. There is also another while loop running constantly in the server that is waiting for sockets to connect. The loop does not run constantly at the line socket.accept(); it stops and just waits.
The User, split into a menu and chat window, has two threads as well. I explain what the threads do before the code. After I originally posted I put a 100 ms sleep in all my threads. CPU Usage is still at 100%*
This thread listens for input from the user. The input tells the server what action to take. There is a thread running for every user currently connected to the server.
public void run()
{
try
{
input = new DataInputStream(user.getSocket().getInputStream());
output = new DataOutputStream(user.getSocket().getOutputStream());
[code]....
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Feb 21, 2014
What is the usage of garbage collector in java.
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Mar 18, 2015
I would like to limit my bandwidth usage when accessing/downloading files (similar to the --limit-rate 50K option for curl and wget) as the website has limited bandwidth. I am not exactly sure how to implement this, but I'm guessing it be accomplished via the BufferedReader? I have attached the current code below.
import java.io.OutputStream;
import java.io.BufferedReader;
import java.io.InputStreamReader;
[Code]....
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May 22, 2015
I am a beginning programmer and was learning how to make an XML. It was for a simple game and only needs to hold the highscores of three different levels. Here is what I coded:
try {
OutputStream fout= new FileOutputStream("highScores.xml");
OutputStream bout= new BufferedOutputStream(fout);
OutputStreamWriter out = new OutputStreamWriter(bout, "8859_1");
[code]....
My issue is that I run this code every time I create the program and the scores are reset to 0. How can I make a small change so that I only run this block of code and create the XML the first time the program is run?
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Dec 7, 2014
I'm trying to write a program that asks a user how many high scores they want on a table, then the users types the inital highscores and is repeatedly asked to place more high scores on the table, which if larger than any existing high score, will take its place and shift the other scores down.
Although for the shifting and inserting of that next score the code just doesnt seem to be working, the insertScore function is where im getting the main exception, and im not sure why?
import java.util.Arrays;
import java.util.Collections;
import java.util.Scanner;
public class HighScores {
public static void main(String[] args) {
[Code] .....
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Jun 17, 2014
Declaring the method as static precludes one from using any sort of object oriented programming, thus the method cannot access instance fields of the object if it needs to.
I created two short classes to sort of find out what this meant, but I feel I do not understand it well enough.
Test class (main):
package votek;
public class Test {
public static void main(String[] args) {
SomeMethod();
}
public static void SomeMethod() {
Character character = new Character();
character.totalLevel = 50;
System.out.println(character.totalLevel);
}
}
Character class:
package votek;
public class Character {
private int level = 0;
public Character() {
level = 50;
}
}
OR
Does it mean that making a static method in the class with private instances will prevent the method from using the private instances?
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Mar 7, 2015
I've spent almost 3 hours on googling about java beans and where it is usable. What I've figured out is that a bean has a public non-arg constructor, properties and getters/setters to manipulate them. I also know that a bean contains no logic, only fields. However, I don't fully understand why I need to use beans instead of normal classes even if a class can do the same things like a bean? Are beans used to store data or what?
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Feb 3, 2015
When it comes to Java EE I see many developers having trouble with the usage of transactions and exceptions and when to use what.
I see a full chapter of RESTful Web Services, but do you also relate these Web Services to their counterparts (SOAP Web Services)?
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Dec 6, 2014
I am stuck on what to put in my functions for this question: Write a program to maintain a list of the high scores obtained in a game. The program should first ask the user how many scores they want to maintain and then repeatedly accept new scores from the user and should add the score to the list of high scores (in the appropriate position) if it is higher than any of the existing high scores. You must include the following functions:
-initialiseHighScores () which sets all high scores to zero.
-printHighScores() which prints the high scores in the format: "The high scores are 345, 300, 234", for all exisiting high scores in the list (remember that sometimes it won't be full).
-higherThan() which takes the high scores and a new score and returns whether the passed score is higher than any of those in the high score list.
-insertScore() which takes the current high score list and a new score and updates it by inserting the new score at the appropriate position in the list
here are my functions the insertScore is missing because I am having troubles with it.
public static void initialiseHighScores (int[] scores, int size)
{
for (int i = 0; i < size; i++)
{
scores [i] = 0;
}
}
public static boolean higherThan (int[] scores, int size, int newScore)
{
[Code]...
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Jun 27, 2014
I found this method from the same link from which I found the Pandigital method. This method uses the algorithm of sieve of eratosthenes who was a greek mathematician and showed how to find prime numbers by taking an individual number and finding the multiples of it and cut them out for they will not be a prime number. From what I've seen this program gives the results much faster than the traditional way of searching for prime numbers by diving that number by the digits upto half of that number and check for divisiblity.
Well, here's the code
public int[] ESieve(int upperLimit) {
int sieveBound = (int)(upperLimit - 1) / 2;
int upperSqrt = ((int)Math.Sqrt(upperLimit) - 1) / 2;
BitArray PrimeBits = new BitArray(sieveBound + 1, true);
for (int i = 1; i <= upperSqrt; i++) {
if (PrimeBits.Get(i)) {
[Code] .....
As seen from the full program on the site [URL] .... this program was formely writen in C++ and from there I've scrapped out this method as the syntax are corresponding to that of Java, but one problem I faced was in finding the BitArray class in Java. I was unable to understand the approach of this program to find the prime numbers.
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Apr 7, 2014
I want to get current RAM usage of my computer and display it in Console View of Eclipse? How can I achieve this?
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