How does requires and exports behave in multithreaded code?

In Java, the `requires` and `exports` keywords are part of the Java Platform Module System (JPMS) introduced in Java 9. In a multithreaded application, the behavior of modules can influence how threads access shared resources. The `requires` clause specifies dependencies between modules, while the `exports` clause defines what is accessible to other modules.

When using these keywords in a multithreaded environment, it’s crucial to understand thread safety, as modules might be handling shared states. The isolation provided by modules can help in encapsulating behaviors, but developers must still ensure that shared resources are properly synchronized to avoid race conditions.

For example, a module exporting a resource should ensure that any mutable shared state is adequately protected, as multiple threads may attempt to access and modify it simultaneously. Proper use of synchronization techniques or concurrent data structures provided by Java can enhance the thread safety of such modules.