> On 15 May 2023, at 23:24, Brice Dutheil <brice.duth...@gmail.com> wrote: > > Hi, > > I do share some concerns of the community, however many have voiced it with a > better english that I could ever do. But I'd like to mention two things: > > 1. There is another usage that I think will be visibly impacted : in tests > it's often necessary to alter part of the system to stress some parts. In > doing so some libraries offer these capabilities, often by relying on an ad > hoc agent ; I hope this falls in the useful application of this mechanism. I > understand the goal is mostly about applications running in production, yet > it's likely the effect will be visible well before code reaches production.
The informational JEP linked at the beginning of this one (https://openjdk.org/jeps/8305968) refers to this use-case when it comes to both agents and other encapsulation-breaking mechanisms: > For white-box testing of code in user modules, build tools and testing > frameworks should automatically emit --add-exports, --add-opens, and > --patch-module for the module under test, as appropriate (for example, > patching the module under test with the contents of the test module allows > the testing of package access methods)… APM tools should require the > application to deploy their agents with the -javaagent or -agentlib option. > This explicitly grants the agent permission to instrument and modify classes. > Mocking libraries that employ an agent to change classes' behavior should do > the same. I.e. mocking libraries should load their agent at startup and have no need to load it dynamically. > > 2. I was wondering however about the relation of this JEP with the following > property : > > ``` > -Djdk.attach.allowAttachSelf=true > ``` > > This affects the attachment not agent loading, however I believe this JEP > should at least mention this property as well as it seems directly tied to > one of the mentioned problems about detecting who loads the agent. The JEP already does. It says: > To maintain integrity, JDK 9 and later releases prevent code from connecting > to the current JVM by default. Perhaps I’ll mention the property by name. — Ron
