diff --git a/ExecutionContext/PThreadExecutionContext.swift b/ExecutionContext/PThreadExecutionContext.swift
index 38acae1..2f96330 100644
--- a/ExecutionContext/PThreadExecutionContext.swift
+++ b/ExecutionContext/PThreadExecutionContext.swift
@@ -26,6 +26,9 @@
     import Foundation
     import CoreFoundation
     import Result
+    #if os(Linux)
+        import Glibc
+    #endif
     
     private func thread_proc(pm: UnsafeMutablePointer<Void>) -> UnsafeMutablePointer<Void> {
         let pthread = Unmanaged<PThread>.fromOpaque(COpaquePointer(pm)).takeRetainedValue()
@@ -54,70 +57,137 @@
             pthread_create(thread, nil, thread_proc, UnsafeMutablePointer<Void>(Unmanaged.passRetained(self).toOpaque()))
         }
     }
+    
+    
+    private class RunLoopFinalizer {
+        private let rl: CFRunLoop!
+        init(_ runLoop: CFRunLoop!) {
+            self.rl = runLoop
+        }
+        deinit {
+            CFRunLoopStop(rl)
+        }
+    }
+    
+    private class RunLoopObject {
+        private var cfObject:AnyObject? = nil
+        private let task:SafeTask
+        private let finalizer:RunLoopFinalizer?
+        
+        init(_ task:SafeTask, runLoopFinalizer: RunLoopFinalizer?) {
+            self.task = task
+            self.finalizer = runLoopFinalizer
+        }
+        
+        func addToRunLoop(runLoop:CFRunLoop, mode: CFString) {
+            if cfObject == nil {
+                self.cfObject = createCFObject()
+            }
+            addCFObject(runLoop, mode: mode)
+        }
+        
+        func signal() {}
+
+        private func createCFObject() -> AnyObject? { return nil }
+        
+        private func addCFObject(runLoop:CFRunLoop, mode: CFString) {}
+    }
 
     private func sourceMain(rls: UnsafeMutablePointer<Void>) {
-        let runLoopSource = Unmanaged<RunLoopSource>.fromOpaque(COpaquePointer(rls)).takeUnretainedValue()
-        runLoopSource.cfSource = nil
+        let runLoopSource = Unmanaged<RunLoopObject>.fromOpaque(COpaquePointer(rls)).takeUnretainedValue()
+        runLoopSource.cfObject = nil
         runLoopSource.task()
     }
 
     private func sourceCancel(rls: UnsafeMutablePointer<Void>, rL: CFRunLoop!, mode:CFString!) {
-        let runLoopSource = Unmanaged<RunLoopSource>.fromOpaque(COpaquePointer(rls)).takeUnretainedValue()
-        runLoopSource.cfSource = nil
+        let runLoopSource = Unmanaged<RunLoopObject>.fromOpaque(COpaquePointer(rls)).takeUnretainedValue()
+        runLoopSource.cfObject = nil
     }
 
     private func sourceRetain(rls: UnsafePointer<Void>) -> UnsafePointer<Void> {
-        Unmanaged<RunLoopSource>.fromOpaque(COpaquePointer(rls)).retain()
+        Unmanaged<RunLoopObject>.fromOpaque(COpaquePointer(rls)).retain()
         return rls
     }
 
     private func sourceRelease(rls: UnsafePointer<Void>) {
-        Unmanaged<RunLoopSource>.fromOpaque(COpaquePointer(rls)).release()
+        Unmanaged<RunLoopObject>.fromOpaque(COpaquePointer(rls)).release()
     }
 
-    private class RunLoopSource {
-        private var cfSource:CFRunLoopSource? = nil
-        private let task:SafeTask
+    private class RunLoopSource : RunLoopObject {
         private let priority:Int
 
-        init(_ task: SafeTask, priority: Int = 0) {
-            self.task = task
+        init(_ task: SafeTask, priority: Int = 0, finalizer: RunLoopFinalizer?) {
             self.priority = priority
+            super.init(task, runLoopFinalizer: finalizer)
         }
 
         deinit {
-            if let s = cfSource {
+            if let s = cfObject as! CFRunLoopSource? {
                 if CFRunLoopSourceIsValid(s) { CFRunLoopSourceInvalidate(s) }
             }
         }
-
-        func addToRunLoop(runLoop:CFRunLoop, mode: CFString) {
-            if cfSource == nil {
-                var context = CFRunLoopSourceContext(
-                    version: 0,
-                    info: UnsafeMutablePointer<Void>(Unmanaged.passUnretained(self).toOpaque()),
-                    retain: sourceRetain,
-                    release: sourceRelease,
-                    copyDescription: nil,
-                    equal: nil,
-                    hash: nil,
-                    schedule: nil,
-                    cancel: sourceCancel,
-                    perform: sourceMain
-                )
-                self.cfSource = CFRunLoopSourceCreate(nil, priority, &context)
-            }
-            
-            CFRunLoopAddSource(runLoop, cfSource!, mode)
+        
+        private override func createCFObject() -> AnyObject? {
+            var context = CFRunLoopSourceContext(
+                version: 0,
+                info: UnsafeMutablePointer<Void>(Unmanaged.passUnretained(self).toOpaque()),
+                retain: sourceRetain,
+                release: sourceRelease,
+                copyDescription: nil,
+                equal: nil,
+                hash: nil,
+                schedule: nil,
+                cancel: sourceCancel,
+                perform: sourceMain
+            )
+            return CFRunLoopSourceCreate(nil, priority, &context)
         }
-
-        func signal() {
-            if let s = cfSource {
+        
+        private override func addCFObject(runLoop:CFRunLoop, mode: CFString) {
+            CFRunLoopAddSource(runLoop, (cfObject as! CFRunLoopSource?)!, mode)
+        }
+        
+        override func signal() {
+            if let s = cfObject as! CFRunLoopSource? {
                 CFRunLoopSourceSignal(s)
             }
         }
     }
     
+    private func timerCallback(timer: CFRunLoopTimer!, rlt: UnsafeMutablePointer<Void>) {
+        sourceMain(rlt)
+    }
+    
+    private class RunLoopDelay : RunLoopObject {
+        private let delay:CFTimeInterval
+        
+        init(_ task: SafeTask, delay: CFTimeInterval, finalizer: RunLoopFinalizer?) {
+            self.delay = delay
+            super.init(task, runLoopFinalizer: finalizer)
+        }
+        
+        deinit {
+            if let t = cfObject as! CFRunLoopTimer? {
+                if CFRunLoopTimerIsValid(t) { CFRunLoopTimerInvalidate(t) }
+            }
+        }
+        
+        private override func createCFObject() -> AnyObject? {
+            var context = CFRunLoopTimerContext(
+                version: 0,
+                info: UnsafeMutablePointer<Void>(Unmanaged.passUnretained(self).toOpaque()),
+                retain: sourceRetain,
+                release: sourceRelease,
+                copyDescription: nil
+            )
+            return CFRunLoopTimerCreate(nil, CFAbsoluteTimeGetCurrent()+delay, -1, 0, 0, timerCallback, &context)
+        }
+        
+        private override func addCFObject(runLoop:CFRunLoop, mode: CFString) {
+            CFRunLoopAddTimer(runLoop, (cfObject as! CFRunLoopTimer?)!, mode)
+        }
+    }
+    
     private extension ExecutionContextType {
         func syncThroughAsync<ReturnType>(task:() throws -> ReturnType) throws -> ReturnType {
             var result:Result<ReturnType, AnyError>?
@@ -143,6 +213,18 @@
             thread.start()
         }
         
+        func async(after:Double, task:SafeTask) {
+            let thread = PThread(task: {
+                let sec = time_t(after)
+                let nsec = Int((after - Double(sec)) * 1000 * 1000 * 1000)//nano seconds
+                var time = timespec(tv_sec:sec, tv_nsec: nsec)
+                
+                nanosleep(&time, nil)
+                task()
+            })
+            thread.start()
+        }
+        
         func sync<ReturnType>(task:() throws -> ReturnType) throws -> ReturnType {
             return try syncThroughAsync(task)
         }
@@ -150,7 +232,7 @@
     
     private class SerialContext : ExecutionContextBase, ExecutionContextType {
         private let rl:CFRunLoop!
-        private let ownRunLoop:Bool
+        private let finalizer: RunLoopFinalizer?
 
         #if !os(Linux)
         private static let defaultMode:CFString = "kCFRunLoopDefaultMode" as NSString
@@ -159,7 +241,6 @@
         #endif
         
         override init() {
-            ownRunLoop = true
             var runLoop:CFRunLoop?
             let cond = NSCondition()
             cond.lock()
@@ -172,22 +253,12 @@
             cond.wait()
             cond.unlock()
             self.rl = runLoop!
+            finalizer = RunLoopFinalizer(self.rl)
         }
         
         init(runLoop:CFRunLoop!) {
-            ownRunLoop = false
             rl = runLoop
-        }
-
-        deinit {
-            if ownRunLoop {
-                let runLoop = rl
-                performRunLoopSource(RunLoopSource({
-                        CFRunLoopStop(runLoop)
-                    },
-                    priority: -32768)
-                )
-            }
+            finalizer = nil
         }
         
         #if !os(Linux)
@@ -200,13 +271,18 @@
         }
         #endif
 
-        private func performRunLoopSource(rls: RunLoopSource) {
-            rls.addToRunLoop(rl, mode: SerialContext.defaultMode)
-            rls.signal()
+        private func performRunLoopObject(rlo: RunLoopObject) {
+            rlo.addToRunLoop(rl, mode: SerialContext.defaultMode)
+            rlo.signal()
+            CFRunLoopWakeUp(rl)
         }
         
         func async(task:SafeTask) {
-            performRunLoopSource(RunLoopSource(task))
+            performRunLoopObject(RunLoopSource(task, finalizer: finalizer))
+        }
+        
+        func async(after:Double, task:SafeTask) {
+            performRunLoopObject(RunLoopDelay(task, delay: after, finalizer: finalizer))
         }
         
         func sync<ReturnType>(task:() throws -> ReturnType) throws -> ReturnType {
@@ -240,6 +316,10 @@
             return try inner.sync(task)
         }
         
+        public func async(after:Double, task:SafeTask) {
+            inner.async(after, task: task)
+        }
+        
         public static let main:ExecutionContextType = PThreadExecutionContext(inner: SerialContext(runLoop: CFRunLoopGetMain()))
         public static let global:ExecutionContextType = PThreadExecutionContext(kind: .Parallel)
     }