On Wed, 1 Sep 2021 01:05:32 GMT, Mandy Chung <mch...@openjdk.org> wrote:
>> This reimplements core reflection with method handles. >> >> For `Constructor::newInstance` and `Method::invoke`, the new implementation >> uses `MethodHandle`. For `Field` accessor, the new implementation uses >> `VarHandle`. For the first few invocations of one of these reflective >> methods on a specific reflective object we invoke the corresponding method >> handle directly. After that we spin a dynamic bytecode stub defined in a >> hidden class which loads the target `MethodHandle` or `VarHandle` from its >> class data as a dynamically computed constant. Loading the method handle >> from a constant allows JIT to inline the method-handle invocation in order >> to achieve good performance. >> >> The VM's native reflection methods are needed during early startup, before >> the method-handle mechanism is initialized. That happens soon after >> System::initPhase1 and before System::initPhase2, after which we switch to >> using method handles exclusively. >> >> The core reflection and method handle implementation are updated to handle >> chained caller-sensitive method calls [1] properly. A caller-sensitive >> method can define with a caller-sensitive adapter method that will take an >> additional caller class parameter and the adapter method will be annotated >> with `@CallerSensitiveAdapter` for better auditing. See the detailed >> description from [2]. >> >> Ran tier1-tier8 tests. >> >> [1] https://bugs.openjdk.java.net/browse/JDK-8013527 >> [2] >> https://bugs.openjdk.java.net/browse/JDK-8271820?focusedCommentId=14439430&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14439430 > > Mandy Chung has updated the pull request incrementally with one additional > commit since the last revision: > > minor cleanup and more test case. So here's a benchmark that measures the impact on a real-world use case - the Jackson (de)serialization: https://gist.github.com/plevart/3cdc7c366d03822c915a7b3ccd579421 Visualized comparisons: jdk18+9 vs. mandy: https://jmh.morethan.io/?gists=f81f8e67ec74c3a5c8110a60ddbf38d7,e41df754bfb07df65714b113f7ed08f3 jdk18+9 vs. peter+vh2mh: https://jmh.morethan.io/?gists=f81f8e67ec74c3a5c8110a60ddbf38d7,9bf7e119ffb859e498772f47ba68c709 mandy vs. peter+vh2mh: https://jmh.morethan.io/?gists=e41df754bfb07df65714b113f7ed08f3,9bf7e119ffb859e498772f47ba68c709 Not so much of an impact on a real-world case as artificial benchmarks. ------------- PR: https://git.openjdk.java.net/jdk/pull/5027
