I have a application that reads a PDF, transform the content to collection of TIF files, and send them to Glass Fish Server for saving. Usually there are 1-5 pages and it works nice, but when I got a input file with 100+ pages... it throws error on the transfer. Java heap space at java.util.Arrays.copyOf(Arrays.java:2786) at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:94) Putting more resources is not a good option in my case, so I m looking for a way to optimize it somehow. I store the data in: HashMap<TifProfile, List<byte[]> Is there a better way to store or send them ? EDIT I did some tests and the final collections for PDF with 80 pages has size over 280mb (240 tiffs with different settings inside)