应用程序第一次运行正常，第二次运行后出现以下错误，重启之后运行第一次没问题，第二次又出现问题了。请问是什么原因呢？

警告: The web application [jConnect] is still processing a request that has yet to finish. This is very likely to create a memory leak. You can control the time allowed for requests to finish by using the unloadDelay attribute of the standard Context implementation. Stack trace of request processing thread:
 java.net.SocketInputStream.socketRead0(Native Method)
 java.net.SocketInputStream.read(Unknown Source)
 java.net.SocketInputStream.read(Unknown Source)
 java.net.SocketInputStream.read(Unknown Source)
 org.rosuda.REngine.Rserve.protocol.RTalk.request(RTalk.java:213)
 org.rosuda.REngine.Rserve.protocol.RTalk.request(RTalk.java:180)
 org.rosuda.REngine.Rserve.protocol.RTalk.request(RTalk.java:250)
 org.rosuda.REngine.Rserve.RConnection.eval(RConnection.java:231)
 com.main.service.Execute.getRobj(Execute.java:54)
 com.main.web.ExecuteR.doGet(ExecuteR.java:41)
 com.main.web.ExecuteR.doPost(ExecuteR.java:55)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
 org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
 org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
 org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
 org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
 org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
 org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
 org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
 org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)
 org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
 org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
 org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
 org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
 org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
 org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1132)
 org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
 org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
 org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
 java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
 java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
 org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
 java.lang.Thread.run(Unknown Source)

下面是我的代码：

1.servlet类

package com.main.web;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.rosuda.REngine.REXP;
import org.rosuda.REngine.Rserve.RConnection;
import org.rosuda.REngine.Rserve.RserveException;

import com.main.service.Execute;
import com.main.util.Rservel;

/**
 * Servlet implementation class ExecuteR
 */
@WebServlet("/ExecuteR")
public class ExecuteR extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ExecuteR() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String RSentences=request.getParameter("data");//这个例子必须到页面点击
        //System.out.println(RSentences);
        Execute wc=new Execute();
        REXP xp;
        try {
            xp = wc.getRobj(RSentences);//获得R对象
            wc.createPlot(xp,wc);//
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

2.com.main.service.Execute类

package com.main.service;


import java.awt.Graphics;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.HeadlessException;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;


import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;

import org.rosuda.REngine.REXP;
import org.rosuda.REngine.Rserve.RConnection;

import com.main.util.Rservel;

public class Execute extends JFrame{
private static final long serialVersionUID=1L;
static Image img;
    public static REXP getRobj(String RSentences) throws Exception{
        RConnection c=Rservel.getRConnection();
        c.setStringEncoding("utf8");//设置字符编码
        //返回R的版本
        REXP Rservesion=c.eval("R.version.string");
        System.out.println("12:"+Rservesion.asString());
        
        String [] arr = RSentences.split("\\s+");
        for(String RSentence : arr){
            System.out.println("done");
        }
        
        
        REXP xp=c.parseAndEval("jpeg('test.jpg',quality=90)");
        c.eval("install.packages('RColorBrewer')");
        c.eval("library(RColorBrewer)");
        c.eval("H <- c(7,12,28,3,41)");
        c.eval("colors<-brewer.pal(5,'Set1')");
        c.parseAndEval(" barplot(H,rep(1,5),col=colors);dev.off()");
        xp=c.parseAndEval("r=readBin('test.jpg','raw',3000*3000);unlink('test.jpg');r");
        c.close();
        return xp;
    }
    public void createPlot(REXP xp, JFrame f)throws Exception{
        Image image=Toolkit.getDefaultToolkit().createImage(xp.asBytes());
        BufferedImage bufferedImage=toBufferedImage(image);
        try {
           ImageIO.write(bufferedImage, "JPG", new File("./outImg/98.jpg"));
       } catch (IOException e) {
           e.printStackTrace();
       }
    }

    public  BufferedImage toBufferedImage(Image image) {  
        if (image instanceof BufferedImage) {  
            return (BufferedImage)image;  
         }  
         image = new ImageIcon(image).getImage();  
         BufferedImage bimage = null;  
         GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();  
        try {  
             
            int transparency = Transparency.OPAQUE;   
             GraphicsDevice gs = ge.getDefaultScreenDevice();  
             GraphicsConfiguration gc = gs.getDefaultConfiguration();  
             bimage = gc.createCompatibleImage(  
             image.getWidth(null), image.getHeight(null), transparency);  
         } catch (HeadlessException e) {  
         }  
        
        if (bimage == null) {   
            int type = BufferedImage.TYPE_INT_RGB;   
             bimage = new BufferedImage(image.getWidth(null), image.getHeight(null), type);  
         }  
         Graphics g = bimage.createGraphics();  
         g.drawImage(image, 0, 0, null);  
         g.dispose();  
        
        return bimage;  
    } 

}