A DESCRIPTION OF THE REQUEST :
When attempting to overwrite a file that exists, Hotspot yields "File exists" and exits code 0.

I believe the problem is here:
 http://hg.openjdk.java.net/hsx/hsx25/hotspot/annotate/539144972c1e/src/share/vm/services/heapDumper.cpp#l449

I am not certain, but it appears if the boolean were changed to true, it would overwrite the specified file.
 _fd = os::create_binary_file(path, false);
to
 _fd = os::create_binary_file(path, true);

JUSTIFICATION :
Centralized virtual machine storage can use smaller attached disks per VM. For memory-intensive Java applications, memory can exceed allocated virtual disk resources. Making heap dumps with jmap and analyzing them off the server is the only way I know how to point to an offending class with excessive memory consumption without adding additional overhead with a profiler. If Hotspot were to write to the specified file regardless of existence, the target file could be a FIFO with an attached process that pipes the memory contents off-server, bypassing writing to disk.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Write the heap dump to the specified file regardless of its existence.
ACTUAL -
Prints to stdout:
Dumping heap to <file path> ...
File exists

Exitcode: 0


---------- BEGIN SOURCE ----------
#!/bin/bash

# Requires a running java process as the user running this script.

touch /tmp/test.hprof
jmap -dump:file=/tmp/test.hprof $(pgrep java)

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

CUSTOMER SUBMITTED WORKAROUND :
Potential bypasses include writing to a separate disk, a mount, or enlarging the disk on the virtual machine.