Background:I am working in a Java environment using Spring Boot, where I often encounter scenarios where global variable state management is critical, especially within singleton services. I have been exploring the idea of using annotations to automate cleanup global variable after used.
Goal:My objective is to streamline global variable management using annotations, enhancing code clarity and maintaining thread safety across singleton services.
Proposed Solution:I propose creating a custom annotation, let's call it@CleanAfterUse, that leverages ThreadLocal under-the-hood. This annotation would handle initialization, management, and cleanup of thread-local state automatically, reducing boilerplate code and potential errors.
Questions:
What are the best practices for implementing annotations in Java to manage ThreadLocal variables effectively?Are there alternative approaches within the Java ecosystem that could achieve similar thread-local state management goals?
- I'm not sure, in your scenario, how you know when to cleanup a global resource. Are you planning to create and destroy these resources on every use?JimmyJames– JimmyJames2024-07-05 18:54:06 +00:00CommentedJul 5, 2024 at 18:54
- @JimmyJames I'm just worried that this would encourage the casual use of globals. The biggest argument against them isn't technical. It's what they do to us humans.candied_orange– candied_orange2024-07-05 19:12:20 +00:00CommentedJul 5, 2024 at 19:12
- 2Can youedit your question to clarify something that might be ambiguous? Java doesn't have the concept of a literal global variable, at least not like some other languages where you declare an identifier as
global. Global can mean an object passed around by dependency injection from object to object, where "global" is more of a concept that a language feature.Greg Burghardt– Greg Burghardt2024-07-05 19:30:04 +00:00CommentedJul 5, 2024 at 19:30 - 1@MuhammadHaris Please edit your question to say what you actually mean, at the moment it's very confusing for a reader when you refer to "global variables" when you don't actually mean global variables.Philip Kendall– Philip Kendall2024-07-06 16:06:29 +00:00CommentedJul 6, 2024 at 16:06
- 1The problem with widely shared class level variables is shared mutable state. If you have some automatic fix for that please explain. Because that is a tall order. It’s not just “cleaning up”.candied_orange– candied_orange2024-07-06 19:24:40 +00:00CommentedJul 6, 2024 at 19:24
1 Answer1
According to Spring framework documentation section "Spring Framework / Core Technologies / The IoC Container / Bean Scopes" the IOC container supports following bean scopes.
| Scope | Description |
|---|---|
| singleton | (Default) Scopes a single bean definition to a single object instance for each Spring IoC container. |
| prototype | Scopes a single bean definition to any number of object instances. |
| request | Scopes a single bean definition to the lifecycle of a single HTTP request. That is, each HTTP request has its own instance of a bean created off the back of a single bean definition. Only valid in the context of a web-aware Spring ApplicationContext. |
| session | Scopes a single bean definition to the lifecycle of an HTTP Session. Only valid in the context of a web-aware Spring ApplicationContext. |
| application | Scopes a single bean definition to the lifecycle of a ServletContext. Only valid in the context of a web-aware Spring ApplicationContext. |
| websocket | Scopes a single bean definition to the lifecycle of a WebSocket. Only valid in the context of a web-aware Spring ApplicationContext. |
Alternatively to developing a new aspect to clean up an existing instance would it be suitable to use a new instance every time and make use of prototype scope?
The answer it is a question since Spring framework uses scopes related to beans and uses aspects on cross cutting concerns (e.g. for transactions, for exception handling so on and so forth)
Explore related questions
See similar questions with these tags.