Use the workQueue.

Author: johnno1962

Foundation/URLSession/URLSession.swift

@@ -198,7 +198,6 @@ open class URLSession : NSObject {
     /// - Note: It's a **concurrent** queue.
     internal let taskAttributesIsolation: DispatchQueue 
     internal let taskRegistry = URLSession._TaskRegistry()
-    fileprivate let identiferLock = NSLock()
     fileprivate let identifier: Int32
     fileprivate var invalidated = false
     fileprivate static let registerProtocols: () = {
@@ -407,7 +406,7 @@ extension URLSession._Request {
 
 fileprivate extension URLSession {
     func createNextTaskIdentifier() -> Int {
-        return identiferLock.synchronized {
+        return workQueue.sync {
             let i = nextTaskIdentifier
             nextTaskIdentifier += 1
             return i