JasperReport size limit

Question

Is there a way to set a limit on the size of a JasperReport? We just looked at a WebSphere 6.1 Heapdump and someone tried to create a report and it was 1.5GB of memory in the h

Answer 1

I'm not familiar with JasperReports, but you could wrap your I/O streams to ensure that the amount of data read/written does not exceed a defined limit.

OutputStream example:

public class LimitedSizeOutputStream extends OutputStream {

    private final OutputStream delegate;
    private final long limit;
    private long written = 0L;

    /**
     * Creates a stream wrapper that will throw an IOException if the write
     * limit is exceeded.
     * 
     * @param delegate
     *            the underlying stream
     * @param limit
     *            the maximum number of bytes this stream will accept
     */
    public LimitedSizeOutputStream(OutputStream delegate, long limit) {
        this.delegate = delegate;
        this.limit = limit;
    }

    private void checkLimit(long byteCount) throws IOException {
        if (byteCount + written > limit) {
            throw new IOException("Exceeded stream size limit");
        }
        written += byteCount;
    }

    @Override
    public void write(int b) throws IOException {
        checkLimit(1);
        delegate.write(b);
    }

    @Override
    public void write(byte[] b) throws IOException {
        checkLimit(b.length);
        delegate.write(b);
    }

    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        checkLimit(len);
        delegate.write(b, off, len);
    }

    @Override
    public void close() throws IOException {
        delegate.close();
    }

}

It is just as easy to wrap an InputStream.

Answer 2

Have you tried limiting the rows in the recordset returned from the database?

Answer 3

JasperReports now has "report governors" that limit the size of report output. For example, you can set these config params:

net.sf.jasperreports.governor.max.pages.enabled=[true|false]

net.sf.jasperreports.governor.max.pages=[integer]

See this posting on the JasperReports forums for more info.