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:
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    - 'Overview': index.md
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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)
  }

  inline fun <T> RealConnection.withLock(action: () -> T): T {

   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

_2014-03-29_

 * Fix bug where the Content-Length header was not always dropped when

import java.lang.ref.WeakReference
import java.net.Socket
import java.util.concurrent.CopyOnWriteArrayList
import java.util.concurrent.ExecutorService
import java.util.concurrent.RejectedExecutionException
import java.util.concurrent.TimeUnit.MILLISECONDS
import java.util.concurrent.atomic.AtomicBoolean
import java.util.concurrent.atomic.AtomicInteger
import java.util.concurrent.locks.ReentrantLock
import okhttp3.Call
import okhttp3.Callback

### EventListener.Factory

In the preceding example we used a field, `callStartNanos`, to track the elapsed time of each event. This is handy, but it won’t work if multiple calls are executing concurrently. To accommodate this, use a `Factory` to create a new `EventListener` instance for each `Call`. This allows each listener to keep call-specific state.

 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package okhttp3

import java.util.concurrent.TimeUnit
import okhttp3.internal.concurrent.TaskRunner
import okhttp3.internal.connection.FastFallbackExchangeFinder
import okhttp3.internal.connection.ForceConnectRoutePlanner
import okhttp3.internal.connection.RealConnectionPool

import java.net.Proxy
import java.net.Socket
import java.net.SocketException
import java.security.cert.X509Certificate
import java.util.concurrent.TimeUnit.MILLISECONDS
import java.util.concurrent.locks.ReentrantLock
import javax.net.ssl.SSLPeerUnverifiedException
import javax.net.ssl.SSLSocket
import kotlin.concurrent.withLock
import okhttp3.Address
import okhttp3.Connection
import okhttp3.ConnectionListener
import okhttp3.Handshake

import java.io.Closeable
import java.io.IOException
import java.net.InetSocketAddress
import java.net.ServerSocket
import java.net.Socket
import java.util.concurrent.BlockingQueue
import java.util.concurrent.Executors
import java.util.concurrent.LinkedBlockingQueue
import java.util.logging.Logger
import okhttp3.TestUtil.threadFactory
import okhttp3.internal.closeQuietly
import okio.Buffer
import okio.BufferedSource

import assertk.assertions.isCloseTo
import assertk.assertions.isFalse
import assertk.assertions.isInstanceOf
import assertk.assertions.matchesPredicate
import java.util.Deque
import java.util.concurrent.ConcurrentLinkedDeque
import java.util.concurrent.TimeUnit
import okhttp3.ConnectionEvent.NoNewExchanges
import okhttp3.internal.connection.RealConnection
import okio.IOException
import org.junit.jupiter.api.Assertions