RFR: 8333344: JMX attaching of Subject does not work when security manager not allowed [v13]

[Weijun Wang]

On Fri, 14 Jun 2024 15:26:54 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

>> JMX uses APIs related to the Security Mananger which are deprecated.  Use of AccessControlContext will be removed when Security Manager is removed.
>> 
>> Until then, updates are needed to not require setting  -Djava.security.manager=allow to use JMX authentication.
>
> Kevin Walls has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Unnecessary catches to remove

src/java.management/share/classes/javax/management/monitor/Monitor.java line 1542:

> 1540:             if (!SharedSecrets.getJavaLangAccess().allowSecurityManager()) {
> 1541:                 // No SecurityManager permitted:
> 1542:                 Subject.doAs(s, action); // s is permitted to be null

While `s` is permitted to be null, calling `Subject.doAs(null, action)` actually sets the current subject to null while calling `action`. This is not same as directly calling `action` where the current subject (could be non null) is used.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19624#discussion_r1641593366