Getting unusual behavior using a BufferedInputStream on a 5 GB file

Question

I have a utility that reads the first 1000 records of a file, the middle 1000 records of a file, and the last 1000 records of a file, to check for data integrity. It has worked like a champ for years on thousands of fairly large files, but has recently been behaving badly on files around 5 GB.
I use a BufferedInputStream with a 8192 buffer size to read the data.
I calculate the line number of the middle 1000 records. After processing the 1st 1000 records, I count the number of LF characters until I hit the beginning of the middle 1000 records. I have to process around 2.7 gigabytes before I find the byte I want
If the buffer has 8192 bytes in it, and I find the byte I want at position 6251, a subsequent read(_bigByteArr, 0, 8192) only returns 1941 bytes.
This is different behavior than with files < 4GB. On smaller files, the subsequent read(_bigByteArr, 0, 8192) returns the full 8192 bytes.
I'm thinking I'm hitting some internal limit (2147483647?). Has anyone else encountered this behavior, or have any ideas for work-arounds?

Answer 1

Thanks! I looked into using DataInputStream.readFully, but it would have been a little clumsy to implement, so I created a new read method that works:
     *     Wrapper around low-level read.
     *     this is needed because bi.read(bigByteArr,0,_maxBytes) does not
     *     guarantee that _maxBytes will be returned.
     private int read() throws IOException
          int bytesRead=0;
          int curByte=0;
          curByte = (int) _bi.read();
          if (curByte==-1) {
               bytesRead=-1;
          }//if
          else {
               bytesRead++;
               _bigByteArr[0]= (byte) curByte;
               for (int i = 1;i<_maxBytes;i++) {
                    curByte = (int) _bi.read();
                    if (curByte==-1) {
                         _bufOnLastChunk=true;
                         break;
                    }//if
                    _bigByteArr= (byte) curByte;
                    bytesRead++;
               }//for
          }//else
          //this was probably already flagged, but if equal to _maxBytes, need to flag
          if (bytesRead==_numBytes) {
               _bufOnLastChunk=true;
          }//if
          return bytesRead;
     }//read
Thanks again for your response and advise!