RFR: 8349206: j.u.l.Handler classes create deadlock risk via synchronized publish() method [v12]

[Daniel Fuchs]

On Wed, 2 Apr 2025 13:39:22 GMT, David Beaumont <duke at openjdk.org> wrote:

>> 8349206: j.u.l.Handler classes create deadlock risk via synchronized publish() method.
>> 
>> 1. Remove synchronization of calls to publish() in Handlers in java.util.logging package.
>> 2. Add explanatory comments to various affected methods.
>> 3. Add a test to ensure deadlocks no longer occur.
>> 
>> Note that this change does not address issue in MemoryHandler (see JDK-8349208).
>
> David Beaumont has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Reworking user warnings about synchronization and deadlocking based on Joe's comments.

src/java.logging/share/classes/java/util/logging/Handler.java line 61:

> 59:  * their {@link #publish(LogRecord)} method, or calls to {@code
> 60:  * super.publish()}, since these are always expected to need to process and
> 61:  * format user-supplied arguments.

I had to read this paragraph twice to realize it didn't say that subclasses shouldn't call
super.publish(). What about slightly changing the wording as follows:

Suggestion:

 * As such, general purpose {@code Handler} subclasses should not synchronize
 * their {@link #publish(LogRecord)} method, or call {@code
 * super.publish()} while holding locks, since these are typically expected to need to process and
 * format user-supplied arguments.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23491#discussion_r2024881280