On Wed, 1 Jun 2022 21:40:43 GMT, Roger Riggs <rri...@openjdk.org> wrote:
> I don't think there is any benefit to the `try{} finally {fence}`. The
> reachabilityFence has no executable code. Its only purpose is to keep the
> reference in scope alive.
...reachability fence has no code, but puting it into finally block makes the
compiler see it on all possible exit paths from the try block (any possible
exceptions, returns, etc.) so the argument 'this' is protected from being GC-ed
until every possible code in try block is finished.
> Ditto, the try/finally is unnecessary.
I think it is necessary for reachability fence since try block has many exit
paths and accesses state cleaned up by Cleaner. Memory fence OTOH is not needed.
> Ditto try/finally is unnecessary.
Perhaps, because there may be only one exit path. But style-wise it is still
better to play safe for any possible future changes to this part of code.
Memory fence is not needed though as explained above.
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PR: https://git.openjdk.org/jdk/pull/8311
