The update release 1.4.2_09 will include some serviceability improvement backports from JDK5.0.
The user visable changes these improvements bring should be documented in the release notes.
There will be additional flags, command line options, and changes to some error message outputs.

The core revisions are detailed at:
http://jpsesvr.sfbay.sun.com:8080/ctetools/html/ViewDetail.jsp?index=1353

The most significant flag change is adding the "OnError" flag. Descriptive information
can be brought back from 5.0.


  xxxxx@xxxxx   2005-03-19 23:27:13 GMT

(Piggy-backing on the same and relevant bug report): B
ackports of the "-XX:OnFirstJavaOutOfMemoryError"  flag 
as well as the jmap utility from JDK5.0 need mention / 
description in JDK1.4.2_09 materials.
  xxxxx@xxxxx   2005-03-29 18:55:37 GMT

N/A

Alan Bateman wrote concisely in his putback comment:
 
    
Fixed 6204527: Need mechanism to run user-defined script/command when OutOfMemoryError is thrown
    
To help diagnose the cause of an OutOfMemoryError we have added a new flag
(OnFirstJavaOutOfMemoryError) which can be used to specify a sequence of 
commands or scripts to execute the first time OOME is thrown. Like the
OnError option, commands are seperated using a semicolon, and %p is 
expanded to be the pid of the VM. 
    
Here are some examples to demonstrate how the flag can be used:
    
This example generates a HPROF heap dump:
  -XX:OnFirstJavaOutOfMemoryError="jmap -heap:format=b %p"
    
This example saves a summary of the objects in the perm gen to a file
and also grabs a core file:
  -XX:OnFirstJavaOutOfMemoryError="jmap -permstat %p > %p.out; gcore %p"
  xxxxx@xxxxx   2005-04-25 16:58:29 GMT