#### Per-Connection Locks

Each connection has its own lock. The connections in the pool are all in a `ConcurrentLinkedQueue`. Due to data races, iterators of this queue may return removed connections. Callers must check the connection's `noNewExchanges` property before using connections from the pool.

The connection lock is never held while doing I/O (even closing a socket) to prevent contention.

    server.bodyLimit = 7 * 512 * 1024
    val connection = server.url("/").toUrl().openConnection() as HttpURLConnection
    connection.setRequestMethod("POST")
    connection.setDoOutput(true)
    connection.setFixedLengthStreamingMode(1024 * 1024 * 1024) // 1 GB
    connection.connect()
    val out = connection.outputStream
    val data = ByteArray(1024 * 1024)
    var i = 0
    while (i < 1024) {

    // 3 different lookups in the connection pool!
    val pooled3 = routePlanner.planReusePooledConnection(this, routes)
    if (pooled3 != null) return pooled3.connection

    connection.withLock {
      connectionPool.put(connection)
      user.acquireConnectionNoEvents(connection)
    }

    user.connectionAcquired(connection)
    user.connectionConnectionAcquired(connection)
    return connection
  }

  /**
   * Close connection after reading the request but before writing the response. Use this to
   * simulate late connection pool failures.
   */
  object DisconnectAfterRequest : SocketPolicy

  /**
   * Half close connection (InputStream for client) after reading the request but before
   * writing the response. Use this to simulate late connection pool failures.
   */

    }
  }

  @Test
  fun testUrlConnectionDirect() {
    testRequest {
      val url = URI(mockServer.endpoint + "/person?name=peter").toURL()

      val connection = url.openConnection() as HttpURLConnection

      assertThat(connection.inputStream.source().buffer().readUtf8()).contains("Peter the person")
    }
  }

  @Test
  fun testUrlConnectionPlaintextProxied() {
    testRequest {

import okhttp3.internal.concurrent.TaskRunner
import okhttp3.internal.connection.CallConnectionUser
import okhttp3.internal.connection.FastFallbackExchangeFinder
import okhttp3.internal.connection.Locks.withLock
import okhttp3.internal.connection.RealCall
import okhttp3.internal.connection.RealConnection
import okhttp3.internal.connection.RealConnectionPool
import okhttp3.internal.connection.RealRoutePlanner
import okhttp3.internal.connection.RouteDatabase

    call: Call,
    connection: Connection,
  ) {
    logWithTime("connectionAcquired: $connection")

    delegate.connectionAcquired(call, connection)
  }

  override fun connectionReleased(
    call: Call,
    connection: Connection,
  ) {
    logWithTime("connectionReleased")

    delegate.connectionReleased(call, connection)
  }

 */
package okhttp3.internal.connection

import java.io.IOException
import java.util.concurrent.CopyOnWriteArrayList
import java.util.concurrent.LinkedBlockingDeque
import java.util.concurrent.TimeUnit
import okhttp3.internal.concurrent.Task
import okhttp3.internal.concurrent.TaskRunner
import okhttp3.internal.connection.RoutePlanner.ConnectResult
import okhttp3.internal.connection.RoutePlanner.Plan

            clientTestRule.wrap(
              object : EventListener() {
                override fun connectionAcquired(
                  call: Call,
                  connection: Connection,
                ) {
                  socketClass = connection.socket().javaClass.name
                }
              },
            ),
          )

okhttp3.internal.concurrent.TaskLoggerTest
okhttp3.internal.concurrent.TaskRunnerRealBackendTest
okhttp3.internal.concurrent.TaskRunnerTest
okhttp3.internal.connection.ConnectionPoolTest
okhttp3.internal.connection.ConnectionSpecSelectorTest
okhttp3.internal.connection.RouteExceptionTest
okhttp3.internal.connection.RouteSelectorTest
okhttp3.internal.http.CancelTest
okhttp3.internal.http.HttpDateTest
okhttp3.internal.http.StatusLineTest