Concurrency
===========

This document describes the concurrency considerations for http/2 connections and the connection pool within OkHttp.

## HTTP/2 Connections

The HttpURLConnection API is a blocking API. You make a blocking write to send a request, and a blocking read to receive the response.

#### Blocking APIs

        # Redirect all contributing pages to contribute/*
        'contributing.md': 'contribute/contributing.md'
        'code_of_conduct.md': 'contribute/code_of_conduct.md'
        'concurrency.md': 'contribute/concurrency.md'
        'debug_logging.md': 'contribute/debug_logging.md'

nav:
  - 'Overview':
    - 'Overview': index.md
    - 'Stack Overflow': https://stackoverflow.com/questions/tagged/okhttp?sort=active

   This adds `OkUrlFactory`, `Cache`, and `@Deprecated` annotations for APIs
   dropped in 2.0.

## Version 1.5.4

_2014-04-14_

 * Drop ALPN support in Android. There's a concurrency bug in all
   currently-shipping versions.
 * Support asynchronous disconnects by breaking the socket only. This should
   prevent flakiness from multiple threads concurrently accessing a stream.

## Version 1.5.3

    misconfigured `ExecutorService` that limited the number of worker threads.
    If you're using `Call.enqueue()` this update should significantly improve
    request concurrency.

 *  **Fix: Lazily initialize the response cache.** This avoids strict mode
    warnings when initializing OkHttp on Android‘s main thread.

 *  **Fix: Disable ALPN on Android 4.4.** That release of the feature was

import okhttp3.Dispatcher
import okhttp3.internal.http2.Http2Connection
import okhttp3.internal.http2.Http2Stream
import okhttp3.internal.http2.Http2Writer

/**
 * Centralisation of central locks according to docs/contribute/concurrency.md
 */
internal object Locks {
  inline fun <T> Dispatcher.withLock(action: () -> T): T {
    contract { callsInPlace(action, InvocationKind.EXACTLY_ONCE) }
    return lock.withLock(action)
  }

Committer's Guides
------------------

 * [Concurrency][concurrency]
 * [Debug Logging][debug_logging]
 * [Releasing][releasing]

 [cla]: https://spreadsheets.google.com/spreadsheet/viewform?formkey=dDViT2xzUHAwRkI3X3k5Z0lQM091OGc6MQ&ndplr=1
 [concurrency]: https://square.github.io/okhttp/concurrency/
 [debug_logging]: https://square.github.io/okhttp/debug_logging/

Committer's Guides
------------------

 * [Concurrency][concurrency]
 * [Debug Logging][debug_logging]
 * [Releasing][releasing]

 [cla]: https://spreadsheets.google.com/spreadsheet/viewform?formkey=dDViT2xzUHAwRkI3X3k5Z0lQM091OGc6MQ&ndplr=1
 [concurrency]: https://square.github.io/okhttp/concurrency/
 [debug_logging]: https://square.github.io/okhttp/debug_logging/