FULL PRODUCT VERSION :


A DESCRIPTION OF THE PROBLEM :
HPROF dumps of a heap containing huge primitive arrays are corrupt due to an integer overflow in DumpWriter::write_raw(void* s, int len).

Imagine there is a byte[] of length Integer.MAX_VALUE - 2.

See the dumper source code from JDK 9 (the same problem with earlier versions too):

void DumpWriter::write_raw(void* s, int len) {
  if (is_open()) {
    // flush buffer to make toom
    if ((position()+ len) >= buffer_size()) { // **** overflow here: position()+ len < 0, the branch is not executed
      flush(); /// *** not reached
    }

    // buffer not available or too big to buffer it
    if ((buffer() == NULL) || (len >= buffer_size())) {
      write_internal(s, len); // *** array bytes are immediately written, but the buffer was not flushed!
    } else {
//...
    }

THE PROBLEM WAS REPRODUCIBLE WITH -Xint FLAG: Did not try

THE PROBLEM WAS REPRODUCIBLE WITH -server FLAG: Yes

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Run the simple example below:

java -Xmx4G -cp . BigArray

2. Dump heap with jconsole or jmap

3. Open the HPROF file in any tool, e.g. MAT

4. Get an error message.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class BigArray {
  public static void main(String[] args) throws Exception {
    final byte[] array = new byte[Integer.MAX_VALUE - 2];

    System.out.println("Dump heap now...");
    System.in.read();
    System.out.println(array);
  }
}

---------- END SOURCE ----------