An example showing a jhat failure in the mlvm fork of Java 1.7 when used with the first example described here: Browsing Memory the JRuby Way.
I'm using JRuby 1.6.0.dev from from the tip of master.
$ jruby -v jruby 1.6.0.dev (ruby 1.8.7 patchlevel 249) (2010-07-31 9771a2b) (Java HotSpot(TM) 64-Bit Server VM 1.6.0_20) [x86_64-java]
There are no errors running the same tests using Java 1.6.0_20.
| [jruby]$ java -version | |
| openjdk version "1.7.0-internal-fastdebug" | |
| OpenJDK Runtime Environment (build 1.7.0-internal-fastdebug-stephen_2010_07_30_11_56-b00) | |
| OpenJDK Server VM (build 19.0-b03-fastdebug, mixed mode) | |
| [jruby]$ cat foo_heap_example.rb | |
| class Foo | |
| end | |
| ary = [] | |
| 10000.times { ary << Foo.new } | |
| puts "ready for analysis!" | |
| sleep | |
| [jruby]$ jruby foo_heap_example.rb | |
| ready for analysis! |
| [dev]$ java -version | |
| openjdk version "1.7.0-internal-fastdebug" | |
| OpenJDK Runtime Environment (build 1.7.0-internal-fastdebug-stephen_2010_07_30_11_56-b00) | |
| OpenJDK Server VM (build 19.0-b03-fastdebug, mixed mode) | |
| [dev]$ which jmap | |
| /usr/local/java-1.7.0/bin/jmap | |
| [dev]$ jps -l | |
| 77647 sun.tools.jps.Jps | |
| 77567 org/jruby/Main | |
| [dev]$ jmap -histo:live 77567 | |
| java.lang.NullPointerException | |
| at java.io.File.<init>(File.java:293) | |
| at sun.tools.attach.BsdVirtualMachine.findSocketFile(BsdVirtualMachine.java:252) | |
| at sun.tools.attach.BsdVirtualMachine.<init>(BsdVirtualMachine.java:65) | |
| at sun.tools.attach.BsdAttachProvider.attachVirtualMachine(BsdAttachProvider.java:63) | |
| at com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:213) | |
| at sun.tools.jmap.JMap.attach(JMap.java:296) | |
| at sun.tools.jmap.JMap.histo(JMap.java:218) | |
| at sun.tools.jmap.JMap.main(JMap.java:138) |