Question

I have the following code which reads in the follow file, append a \r\n to the end of each line and puts the result in a string buffer:

public InputStream getInputStream() throws Exception {
    StringBuffer holder = new StringBuffer();
    try{
        FileInputStream reader = new FileInputStream(inputPath);


        BufferedReader br = new BufferedReader(new InputStreamReader(reader));
        String strLine;
        //Read File Line By Line
        boolean start = true;
        while ((strLine = br.readLine()) != null)   {
            if( !start )    
                holder.append("\r\n");

            holder.append(strLine);
            start = false;
        }
        //Close the input stream
        reader.close();
    }catch (Throwable e){//this is where the heap error is caught up to 2Gb
      System.err.println("Error: " + e.getMessage());
    }


    return new StringBufferInputStream(holder.toString());
}

I tried reading in a 400Mb file, and I changed the max heap space to 2Gb and yet it still gives the out of memory heap exception. Any ideas?

Answer 1

It’s an interesting question, but rather than stress over why Java is using so much memory, why not try a design that doesn’t require your program to load the entire file into memory?