Скачать или смотреть Java Okhttp3 v4 HTTP2 Client multiplexing and concurrency model explained

Today I explain how the Java / Kotlin Okhttp3 HTTP2 Client library handles multiplexing and it’s concurrency and threading model.

3 locks

Http2Connection - lock to update the internal state of connection (important, no IO blocking calls here)
HttpStream - wait/notify to block the application layer thread
Http2writer - to ensure only one thread writes it’s fragments at once (stop interleaving to a socket )

Threads

Application layer thread - actually makes the request and holds the locks. Blocks on httpstream wait/notify.
Single Socket Reader thread - reads messages of the socket and dispatched to the thread pool.
Do stuff later thread pool - maps responses to httpstream, then calls notify to wake the application later thread to continue processing. Threads Also used to respond to pings over the socket .. so not only application level threads gain the http2writer lock.

Connection Pooling
Used to find an open TCP connection / socket to a server with a matching Address.
If no matching socket address is in the pool, a new connection to the socket is established and put into the pool. Protocol is established here and saved.
HTTP2 connections are used simultaneously due to multiplexing (parallel reading/writing on the socket)
Idle and closed connections will be found by the do stuff later pool , and enabled for GC.

I hope you enjoy the video !

Spring boot Graphql series currently being made!

Okhttp
https://square.github.io/okhttp/

Okhttp github
https://github.com/square/okhttp/

Upgrading to OkHttp 4
https://square.github.io/okhttp/upgra...

Download okhttp3 v4 dependency
https://mvnrepository.com/artifact/co...

Have a go and have some fun!
Cheers!
Philip