On Thu, 23 Nov 2023 11:14:29 GMT, Erik Österlund <eosterl...@openjdk.org> wrote:
> The current logic for closing memory in panama today is susceptible to live > lock if we have a closing thread that wants to close the memory in a loop > that keeps failing, and a bunch of accessing threads that want to perform > accesses as long as the memory is alive. They can both create impediments for > the other. > > By using asynchronous handshakes to install an exception onto threads that > are in @Scoped memory accesses, we can have close always succeed, and the > accessing threads bail out. The idea is that we perform a synchronous > handshake first to find threads that are in scoped methods. They might > however be in the middle of throwing an exception or something wild like > there, where an exception can't be delivered. We install an async handshake > that will roll us forward to the first place where we can indeed install > exceptions, then we reevaluate if we still need to do that, or if we have > unwound out from the scoped method. If we are still inside of it, we ensure > an exception is installed so we don't continue executing bytecodes that might > access the memory that we have freed. > > Tested tier 1-5 as well as running test/jdk/java/foreign/TestHandshake.java > hundreds of times, which tests this API pretty well. This pull request has now been integrated. Changeset: 15946532 Author: Erik Österlund <eosterl...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/159465324fc45325d0df438991032ebca9229ca2 Stats: 222 lines in 8 files changed: 76 ins; 63 del; 83 mod 8310644: Make panama memory segment close use async handshakes Reviewed-by: jvernee, mcimadamore, pchilanomate ------------- PR: https://git.openjdk.org/jdk/pull/16792
