On 8/17/2026 4:59 PM, Dan Smith wrote:
On Aug 17, 2026, at 3:04 PM, Kevin Rushforth
<[email protected]> wrote:
That's an interesting question. And one I'll need to drill into when
I get to the WebView Java <--> JS bridge implementation. Up until
now, I've been assuming that we don't care much about whether value
objects leak. For small objects like the boxed primitive classes,
that seems a reasonable assumption (what does it mean to "leak" an
integer?). However, if a user-defined value object (e.g., a simple
value record) contains a large array of integers or a reference to a
user-defined identity object, then I think we do care.
Right. I think there are three kinds of value objects worth keeping in
mind:
- Small primitive data wrappers (the common case)
- Wrappers around identity pointers (including large strings and
arrays, totally reasonable in certain contexts)
- Large identity-free trees of value objects (discouraged)
Yes, that seems like a useful distinction.
Brian talked about holding onto the first category forever, while
releasing the second category once the identity object is otherwise
unreachable. That would probably be an acceptable outcome in practice,
although it leaves the potential for significant memory leaks caused
by the third category. But maybe the third category is a “shoot
yourself in the foot” situation.
On the other hand, if we take seriously the risk of memory leaks
caused by value objects, I’m not sure there’s any acceptable solution:
a value object that gets pinned forever can cause memory leaks, while
a value object that can get released at any future moment, possibly
even immediately, cannot be reliably cached—might as well just be left
out completely.
For WebView's JS bridge case we will need to document this limitation.
Based on the current JEP-401 spec / behavior, the warning will need to
cover both the second and third categories. I will likely call out
Optional specifically, given that it is an existing class that becomes
an identity class, but the general advice will apply to any value class.
-- Kevin
