Integrated: 8282641: Make jdb "threadgroup" command with no args reset the current threadgroup back to the default

[Chris Plummer]

On Fri, 4 Mar 2022 05:37:25 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

> jdb has a probably very little used command called "threadgroup" which is used to set the current TheadGroup. The only purpose of the current ThreadGroup is as the default ThreadGroup to use for the "threads" command when no ThreadGroup argument is passed to it.
> 
> "threads" prints out every thread in the ThreadGroup specified as the first argument. If none is specified, it uses the current ThreadGroup. If the current ThreadGroup has not yet been specified, it automatically gets set to the top level ThreadGroup.
> 
> Once the current ThreadGroup has been set by using the threadgroup command, it's not that obvious how to reset it back to the default. It turns out the way to do this to set it to the "system" ThreadGroup, which is the top level ThreadGroup (and therefore the initial current ThreadGroup).
> 
> With this enhancement I've made it so if you use the "threadgroup" command with no argument, it resets the current ThreadGroup back to the top level ThreadGroup ("system"). Previously with no argument it produces an error for not specifying the ThreadGroup argument.

This pull request has now been integrated.

Changeset: ff766204
Author:    Chris Plummer <cjplummer at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/ff76620487c307514c435443bbaebc9a6c473f5d
Stats:     29 lines in 5 files changed: 15 ins; 3 del; 11 mod

8282641: Make jdb "threadgroup" command with no args reset the current threadgroup back to the default

Reviewed-by: kevinw, amenkov

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PR: https://git.openjdk.java.net/jdk/pull/7687