问题
I need to write a web application which receives a lot of HTTP requests and takes a long time (30s to 2min) to process each request (in turn making other network requests) before returning a response.
Because there would be a lot of requests coming in and those connections are held open I'm thinking of going down an event driven route, which leads me to think Netty is appropriate.
If each request takes a long time to process, is that going to block netty's processing? Or can I receive a request and then asynchronously process it before returning a result to the request's connection?
回答1:
As long as you don't block the event loop, you will be able to serve a significant amount of concurrent requests (depending on the available memory, and the size of the context you're holding for each request).
What you need to do is to make sure you're making the outbound network requests in a non blocking manner. This normally looks like so (in your Netty inbound handler):
CompletableFuture<YourResultType> future = remoteTarget.getStuff();
future.thenApply(ctx::write);
You need to hold a reference to a context / channel if you're doing this outside of the handler of course.
Note that this is a simplified answer. If you're making several outbound requests and have some business logic, you need to stitch your code properly using continuations on the futures, or whatever non-blocking model you are using.
来源：https://stackoverflow.com/questions/54717928/async-processing-of-requests-in-java-webapp