The jmap tools ALWAYS fails on the last build jdk1.7.0b126 (and previous) build. To reproduce the bug:
1. Download jdk1.7.0b126
2. Compile attached test JMapTest.java
3. Run it
4. Try to make dump by the command:
jmap -dump:file=dump <pid>
where <pid> is a pid from item 3

jmap fails! I attached screenshot and the 2815_appcompat.txt file

The bug is reproducible ALWAYS.
Below is my PC config:

   Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 3 (2600.xpsp_sp3_gdr.100427-1636)
           Language: English (Regional Setting: Russian)
               BIOS: BIOS Date: 09/06/06 17:43:50 Ver: 08.00.12
          Processor: Intel(R) Core(TM)2 CPU 6400 @ 2.13GHz (2 CPUs)
             Memory: 3008MB RAM