How to solve java.lang.OutOfMemoryError: Java heap

I am working in real time project.

Working: I am getting data from twitter and moving the output to cassandra database and then using Testrestfull webservice i am getting the output in json format. And then finally outputs are displayed in wep page. i am using glass fish server to connect web service and web page. it is an real time project so i am refreshing my page in every 5 second.

First few seconds i am not getting any error it works fine after 5 to 10 minutes i am getting this error in glass fish server.

Error: WARNING: StandardWrapperValve[genric.ApplicationConfig]: Servlet.service() for servlet genric.ApplicationConfig threw exception java.lang.OutOfMemoryError: Java heap space

I dont know why i am getting this error and how to solve this. Can any one help me.

This is my webservice code:

public String gettweets(String st)
{
 cluster=Cluster.builder().addContactPoint("localhost").build();    
 session=cluster.connect("space");
 String query ="select * from tweet_count where createdtime='"+st+"' allow filtering;";
 ResultSet result = session.execute(query);
 String text = "[";
 for(Row r : result){
    System.out.println(r.getString("tag_name"));
   text+="{\""+"x"+"\":\""+r.getString("tag_name")+"\",\""+"y"+"\":\""+r.getInt("count")+"\"},";

}
text=text.substring(0,text.length()-1);
text+="]";

    return text;
}

This is my web page code:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
</head>
<body onload="load();grid();marqueeload();" style="background-color:white">
<pre style="height:25px;background-color:black;">
<div id = "title" style = "text-align:center;font-size:20px;width:100%;"><span>REAL TIME TWITTER TRENDS</span></div>
</pre>      
<div><table>
<tr><td><lable>Select Date<lable></td><td>  :  </td><td><input id="datepicker" type="text" /></td></tr></table>
</div>
<div style = "width:100%">
<div id="container2" style = "width:670px;height:300px;float:left;background-color:white;border: 1px solid green;">
<div style = "text-align:center;font-size:20px;"><span1>CHART VIEW<span1></div>
<div id="container1"></div>
</div>
<div id="container3" style = "width:670px;overflow-y:auto;height:300px;float:right;background-color:white;border: 1px solid green;"> 
<div style = "text-align:center;font-size:20px;"><span1>GRID VIEW<span1></div>                                  
<div id="Grid"></div>
</div>
</div> 
<div style = "width:100%;border: 1px solid green;height:300px;float:left;background-color:white;">
<div style = "text-align:center;font-size:20px;"><span1>Trending tweets<span1></div>
<marquee id = "marqueeid" direction="up" height="200" scrollAmount=2 scrollDelay=130 class="sidelink" onMouseDown="this.stop()" onMouseOver="this.stop()" onMouseMove="this.stop()" onMouseOut="this.start()" vspace="10" >
</marquee>
</div>
<script type="text/javascript" language="javascript">

function marqueeload()
{

var str;

$.get("http://localhost:8080/WebApplication1/webresources/generic", function(str)
{
str=str.slice(12, str.length-14);
var div=document.getElementById('marqueeid');
div.innerHTML=str;
});
}

$(function () {

             $("#datepicker").ejDatePicker({
            select: "onSelected"
            });
 $("#datepicker").ejDatePicker({ enabled: true });
    });
 function onSelected(args) {
       var str = args.value;
       var newstr = str.split("/",3);
       if(newstr[0].length == 1){
        newstr[0] = '0'+newstr[0];
       }
       if(newstr[1].length == 1){
        newstr[1] = '0'+newstr[1];
       }
       var dat = newstr[2]+'-'+newstr[0]+'-'+newstr[1];
       window.datetweet = dat;
       $("#container1").ejChart("destroy");
       grid();
       load();
}
function load() {

var str;    
$.get("http://localhost:8080/WebApplication1/webresources/time/"+window.datetweet,      function(str)
{

str=str.slice(12, str.length-14);
var data=JSON.parse(str);



        $("#container1").ejChart(
                    {
                        primaryXAxis:
                        {
                            title: { text: 'Tagname' },
                            labelRotation: 45
                        },

                        primaryYAxis:
                       {

                           range: { min: 0, max: 1000, interval: 100 },
                           title: { text: 'Count' }


                       },
                        commonSeriesOptions: {
                            type: 'column', animation: true,
                            tooltipFormat: "#point.x# : #point.y#"
                        },


                        series: [
                            {
                                points: data,


                            }

                        ],
                        load:"loadTheme",
                                                    showTooltip: true,
                        needResize:true,

                        size: { height: 300 },
                        legend: { visible: false, position: 'top' }
                    });

});

    }

$(document).ready(function()
{

    $("#Grid").ejGrid({
    dataSource: [],
                     allowPaging: true,
                     allowSorting: true,

                     columns: [
                             { field: "x", headerText: "Trend Name", textAlign: ej.textAlign.Right, width: 10 },
                             { field: "y", headerText: "Count", textAlign: ej.textAlign.Right, width: 10 }
                    ]
                    });
 });

 function grid()
 {
    var str;

    var url="http://localhost:8080/WebApplication1/webresources/time/"+window.datetweet;

    $.get(url, function(str)
    {
        str=str.slice(12, str.length-14);
        var obj=JSON.parse(str);
        var instance = $("#Grid").ejGrid("instance");
        instance._dataManager = new ej.DataManager(obj);
        $("#Grid").ejGrid("model.dataSource", instance._dataManager);

    });

  }


window.setInterval(function() { load(); grid(); marqueeload(); }, 10000);

</script>

</body>

</html>

回答1:

An OOM or OOME (OutOfMemoryError) simply means that the JVM ran out of memory. When this occurs, you basically have 2 choices:

Allow the JVM to use more memory using the -Xmx VM argument. For instance, to allow the JVM to use 1 GB (1024 MB) of memory:
Improve/Fix the application so that it uses less memory.

For moer info please go through this link

http://www.mkyong.com/eclipse/eclipse-java-lang-outofmemoryerror-java-heap-space/

回答2:

Answer:

Properly close the session object and cluster object

eg :

session.shutdown();
cluster.shutdown();

Thanks to @ceiling gecko

回答3:

Try to configure your JVM to use more memory as shown before (-Xms750m -Xmx2048m -XX:MaxPermSize=1024m ).
Enable Garbage Collection logging (-Xloggc:/var/log/YOUR_APP/YOUR_APP-gc.log) and see how it behaves, how heap is growing. Probably you have a memory leak.
If so, take a HeapDump, use YourKit to open it and look for objects that use the largest amount of memory. Try to figure out why and fix it.