CODEWITHSUNDEEP
javamemory
user1713275
user1713275

Reputation: 1

java.lang.outofmemoryError java

I am trying to display 5000 records on page using JSP. But I am getting out of memory exception. I am doing it as,

<TABLE><tr><td>Header1</td><td>Header2</td><td>Header3</td><td>Header4</td><td>Header5</td></tr>");
    <%Test test = new Test();
         List myList = test.fetchdata();

        Iterator itr  = myList.iterator();
        while(itr.hasNext())
        {       
          Object[] row = (Object[]) itr.next();
          String hdr1 = (String) row[0];
          String hdr2 = (String) row[1];
          String hdr3 = (String) row[2];
          String hdr4 = (String) row[3];
          String hdr5 = (String) row[4];
              stringBuilder.append"<tr><td>'"+hdr1+"'</td><td>'"+hdr2+"'</td><td>'"+hdr3+"'</td><td>'"+hdr4+"'</td><td>'"+hdr5+"'</td></tr>");              
        }
 stringBuilder.append("</TABLE></body></html>");
 out.print(stringBuilder.toString()); 
  %>

1) if I want to decide to keep 5000 records on screen , is there anything wrong in my code

2) Or will this error will go if I use pagination etc ?

Upvotes: 0

Views: 160

Answers (2)

Fabian Lange
Fabian Lange

Reputation: 1856

Because your code example is somehow broken it is hard to say, but there are two places that cause the memory problem. A) your test.fetchdata() B) your append to the StringBuilder

Starting with B, if you are directly on the JSP you could try outputting it directly, rather than to use the StringBuilder. Depending on the JSP compiler it might produce smaller StringBuilders that should not take up much memory.

But most likely the Problem is in A. You get back a long list which already occupies a lot memory. You can only optimize by doing some lazy loading of results (in the iterator) or as you proposed yourself by pagination (which is recommendable, as all the comments indicate :-) )

And there is one last option maybe worth trying when there are lots of duplicate strings. inside the fetchdata() method use .intern() before you store the String in the array. This prevents multiple identical strings to take up additional heap at the cost of a bit cpu time for calculating this.

Upvotes: 1

Logan
Logan

Reputation: 2374

I was thinking something more like this with append.

    List myList = test.fetchdata();

    Iterator itr = myList.iterator();

    StringBuilder stringBuilder = new StringBuilder("");

    while (itr.hasNext()) {
        Object[] row = (Object[]) itr.next();
        String hdr1 = (String) row[0];
        String hdr2 = (String) row[1];
        String hdr3 = (String) row[2];
        String hdr4 = (String) row[3];
        String hdr5 = (String) row[4];
        stringBuilder.append("<tr><td>'").append(hdr1)
                .append("'</td><td>'").append(hdr2).append("'</td><td>'")
                .append(hdr3).append("'</td><td>'").append(hdr4)
                .append("'</td><td>'").append(hdr5).append("'</td></tr>");
    }
    stringBuilder.append("</TABLE></body></html>");
    out.print(stringBuilder.toString());

Or possibly refactoring that into this.

    List myList = test.fetchdata();

    Iterator itr = myList.iterator();

    StringBuilder stringBuilder = new StringBuilder("");

    while (itr.hasNext()) {
        Object[] row = (Object[]) itr.next();
        stringBuilder.append("<tr><td>'").append(row[0])
                .append("'</td><td>'").append(row[1]).append("'</td><td>'")
                .append(row[2]).append("'</td><td>'").append(row[3])
                .append("'</td><td>'").append(row[4]).append("'</td></tr>");
    }
    stringBuilder.append("</TABLE></body></html>");
    out.print(stringBuilder.toString());

Upvotes: 0

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