Both Java and Kotlin are languages that are heavily used in Distributed Systems, handling multiple asynchronous operations simultaneously. Blocking is not an option in such an environment, but let’s be honest, we crave for the easier synchronous world. That’s why JVM as a platform has an inherent focus on providing an easier option of multithreaded programming. Today, I’d like to compare two of such options - Kotlin Coroutines and Project Loom, that want to provide fibers and continuations to core Java.

1. TO B E CO N T I N U E D
K O T L I N C O U R O U T I N E S & P R O J E C T L O O M
A R T U R S KO W R O Ń S K I

4. A N Y B O D Y K O T L I N ?

5. B Y J E T B R A I N S
2 0 1 1

8. K O T L I N 1 . 3
1 0 . 2 0 1 8

9. K O T L I N 1 . 3
1 0 . 2 0 1 8
COROUTINES

10. W I L L T E A C H Y O U H O W C O R O U T I N E S W O R K S

11. W O N ’ T T E A C H Y O U H O W - T O - C O R O U T I N E

13. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

14. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

15. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

16. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

17. SYNCHRONOUS
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

18. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

19. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

20. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

21. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

22. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

23. CALLBACKS
fun main(args: Array<String>) {
getLocationsNearCoordinates("SW8 5YY, UK")
.success {location ->
val category = location.classification.category
if (category == "Store") {
getStoreDetails(location.id)
.success { locationWrapper ->
val openingHours = locationWrapper
.openingHours
.first()
.standardOpeningHours
println("Store Opening Hours: $openingHours")
}
}
if (category == "Office") {
payOfficeRent(location.id)
.success {
println("Invoice paid")
}
}
}
}

24. A LT E R N AT I V E S

25. COMPUTABLE FUTURES
fun combineAsync(name1: String, name2: String): CompletableFuture<Image>{
val future1 = CompletableFuture.supplyAsync(name1-> ...)
val future2 = CompletableFuture.supplyAsync(name2-> ...)
return future1.thenCombine(future2){i1,i2 -> ...}
}

26. REACTIVE EXTENSIONS
Observable<String> getTitle() {
return Observable.from(titleList);
}
Observable.just("book1", "book2")
.flatMap(s -> getTitle())
.subscribe(l -> result += l);
assertTrue(result.equals("titletitle"));

27. C O M P L E X I T Y

28. E X C E P T I O N H A N D L I N G I S H A R D

29. O V E R A L L I T ’ S H A R D

30. IMPERATIVE CODE
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

31. C O R O U T I N E S

32. 1 9 5 8

34. 1 9 6 3

35. NATIVE SUPPORT

36. NATIVE?

37. IMPERATIVE CODE
fun main(args : Array<String>) {
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
fun getLocationNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours
}
fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

38. COROUTINE CODE
fun main() {
GlobalScope.launch {
val location = getLocationsNearKnownPostcode().first()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
runBlocking {
delay(2000L)
}
}
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

39. COROUTINE CODE
fun main() {
GlobalScope.launch {
val location = getLocationsNearKnownPostcode().first()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
runBlocking {
delay(2000L)
}
}
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

40. COROUTINE CODE
fun main() {
GlobalScope.launch {
val location = getLocationsNearKnownPostcode().first()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
runBlocking {
delay(2000L)
}
}
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

41. COROUTINE CODE
fun main() {
GlobalScope.launch {
val location = getLocationsNearKnownPostcode().first()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
runBlocking {
delay(2000L)
}
}
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

42. COROUTINE CODE
fun main() {
GlobalScope.launch {
val location = getLocationsNearKnownPostcode().first()
val category = location.classification.category
if (category == "Store") {
val openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category == "Office") {
payInvoice(location.id)
println("Invoice paid")
}
}
runBlocking {
delay(2000L)
}
}
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

43. BLOCKING
THREAD
Function 1
Function 2

44. SUSPEND
Suspension Point
THREAD
Function 1
Function 2

45. SUSPEND
THREAD
Coroutine 1
Function 2
getLocationsNearKnownPostcode getOpeningHours
Function 3

46. C O N T I N U AT I O N S

47. C O N T I N U AT I O N S

48. DIRECT STYLE CODE
val location = getLocationsNearKnownPostcode()
val category = location.classification.category
ActionResult
Continuation
ACTION + RESULT & CONTINUATION

49. CONTINUATION PASSING STYLE
getLocationsNearKnownPostcode()
.success {location ->
val category = location.classification.category
}
Action
Result

50. CONTINUATION PASSING STYLE
getLocationsNearKnownPostcode()
.success {location ->
val category = location.classification.category
}
Action
Result
FANCY NAME FOR CALLBACKS

51. FROM KOTLIN FILE
suspend fun getLocationsNearKnownPostcode(): List<LocationWrapper> {
return getLocationsNearCoordinates("SW8 5YY, UK")
}
suspend fun getOpeningHours(id: String): Any {
return getStoreDetails(id).openingHours.first().standardOpeningHours
}
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

52. JVM BYTECODE
public final static getLocationsNearKnownPostcode(Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
L0
LINENUMBER 33 L0
LDC "SW8 5YY, UK"
INVOKESTATIC TescoLocationAPIKt.getLocationsNearCoordinates (Ljava/lang/String;)Ljava/util/List;
ARETURN
L1
MAXSTACK = 1
MAXLOCALS = 1
// access flags 0x19
// signature (Ljava/lang/String;Lkotlin/coroutines/Continuation<Ljava/lang/Object;>;)Ljava/lang/Object;
// declaration: getOpeningHours(java.lang.String, kotlin.coroutines.Continuation<java.lang.Object>)
public final static getOpeningHours(Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 1
L0
LINENUMBER 37 L0
ALOAD 0
INVOKESTATIC TescoLocationAPIKt.getStoreDetails (Ljava/lang/String;)LLocationWrapper;
INVOKEVIRTUAL LocationWrapper.getOpeningHours ()[LLocationOpeningHours;
INVOKESTATIC kotlin/collections/ArraysKt.first ([Ljava/lang/Object;)Ljava/lang/Object;
CHECKCAST LocationOpeningHours
INVOKEVIRTUAL LocationOpeningHours.getStandardOpeningHours ()Ljava/util/HashMap;
ARETURN
L1
LOCALVARIABLE id Ljava/lang/String; L0 L1 0
MAXSTACK = 1
MAXLOCALS = 2
// access flags 0x19
// signature (Ljava/lang/String;Lkotlin/coroutines/Continuation<Ljava/lang/Object;>;)Ljava/lang/Object;
// declaration: payInvoice(java.lang.String, kotlin.coroutines.Continuation<java.lang.Object>)
public final static payInvoice(Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 1
L0
LINENUMBER 41 L0
ALOAD 0
INVOKESTATIC TescoLocationAPIKt.payOfficeRent (Ljava/lang/String;)LLocationResult;
ARETURN
L1
LOCALVARIABLE id Ljava/lang/String; L0 L1 0
MAXSTACK = 1
MAXLOCALS = 2

53. TAKE A LOOK
public final static payInvoice(Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 1
L0
LINENUMBER 41 L0
ALOAD 0
INVOKESTATIC TescoLocationAPIKt.payOfficeRent (Ljava/lang/String;)LLocationResult;
ARETURN
L1
LOCALVARIABLE id Ljava/lang/String; L0 L1 0
MAXSTACK = 1
MAXLOCALS = 2

54. TAKE A LOOK
public final static payInvoice(Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 1
L0
LINENUMBER 41 L0
ALOAD 0
INVOKESTATIC TescoLocationAPIKt.payOfficeRent (Ljava/lang/String;)LLocationResult;
ARETURN
L1
LOCALVARIABLE id Ljava/lang/String; L0 L1 0
MAXSTACK = 1
MAXLOCALS = 2
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

55. TAKE A LOOK
public final static payInvoice(Ljava/lang/String;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@Lorg/jetbrains/annotations/Nullable;() // invisible
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0
@Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 1
L0
LINENUMBER 41 L0
ALOAD 0
INVOKESTATIC TescoLocationAPIKt.payOfficeRent (Ljava/lang/String;)LLocationResult;
ARETURN
L1
LOCALVARIABLE id Ljava/lang/String; L0 L1 0
MAXSTACK = 1
MAXLOCALS = 2
suspend fun payInvoice(id: String): Any {
return payOfficeRent(id)
}

56. CONTINUATION INTERFACE
public interface Continuation<in T> {
public val context: CoroutineContext
public fun resumeWith(result: Result<T>)
}

57. TAKE A LOOK
public final static main()V
L0
LINENUMBER 13 L0
GETSTATIC kotlinx/coroutines/GlobalScope.INSTANCE : Lkotlinx/coroutines/GlobalScope;
CHECKCAST kotlinx/coroutines/CoroutineScope
ACONST_NULL
ACONST_NULL
NEW kotlinx/coroutines/guide/compose01/CoroutineCodeKt$main$1
DUP
ACONST_NULL
INVOKESPECIAL kotlinx/coroutines/guide/compose01/CoroutineCodeKt$main$1.<init> (Lkotlin/coroutines/Continuation;)V
CHECKCAST kotlin/jvm/functions/Function2
ICONST_3
ACONST_NULL
INVOKESTATIC kotlinx/coroutines/BuildersKt.launch$default (Lkotlinx/coroutines/CoroutineScope;Lkotlin/coroutines/CoroutineContext;Lkotlinx/coroutines/
CoroutineStart;Lkotlin/jvm/functions/Function2;ILjava/lang/Object;)Lkotlinx/coroutines/Job;
POP
L1

58. TAKE A LOOK
Coroutine
Stack
Operation 1
Operation 2
Operation 3
SUSPEND FUNCTION
Operation 1
Operation 2
Operation 3
Operation 4
Operation 5
SUSPEND FUNCTION
Operation 4
Operation 5
State
Operation 1
Operation 2
Operation 3

59. P R O J E C T L O O M

60. O P E R AT I N G S Y S T E M S 1 0 1

61. KERNEL SPACE THREADS
P R O C E S S E S
K E R N E L T H R E A D S
OS
PROCESS
PROCESS
THREAD
THREAD
THREAD
THREAD

62. KERNEL SPACE THREADS
C P U S H E D U L E R
THREAD
Instruction 1
Instruction 2
Instruction 3
Instruction 4
THREAD
Continuation

63. OS
C P U S H E D U L E R
THREAD
THREAD
Instruction 1
Instruction 2
Instruction 3
Instruction 4

64. USER/KERNEL SPACE BORDER
CPU SHEDULER JVM
CONTEXT SWITCH

65. P R O J E C T M E T R O P O L I S

66. P R O J E C T VA L H A L L A

67. P R O J E C T PA N A M A

68. P R O J E C T A M B E R

69. P R O J E C T L O O M

70. USER/KERNEL SPACE BORDER
CPU SCHEDULER JVM
FORKJOINSCHEDULER
THREAD
THREAD
THREAD

71. USER/KERNEL SPACE BORDER
CPU SCHEDULER JVM
FORKJOINSCHEDULER
THREAD
Instruction 1
Instruction 2
Instruction 3
Instruction 4
Coroutines

72. CONTINUATION INTERFACE
public class Continuation implements Runnable {
public Continuation(ContinuationScope s, Runnable r)
public final void run()
public static void yield(ContinuationScope s)
public boolean isDone()
}

73. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

74. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

75. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

76. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

77. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

78. CONTINUATIONS
public static void main(String[] args){
ContinuationScope scope = new ContinuationScope("scope")
Continuation continuation = new Continuation(scope, () ->{
var location = getLocationsNearKnownPostcode()
var category = location.classification.category
if (category.equals(”Store”)) {
var openingHours = getOpeningHours(location.id)
println("Store Opening Hours: $openingHours")
}
if (category.equals(“Office")) {
payInvoice(location.id)
println("Invoice paid")
}
})
while (!continuation.isDone()) {
continuation.run();
}
}
public List<LocationWrapper> getLocationNearKnownPostcode() {
return getLocationsNearCoordinates("SW8 5YY, UK”).first()
}
public OpeningHours getOpeningHours(id: String) {
return getStoreDetails(id).openingHours
}
public void payInvoice(id: String) {
return payOfficeRent(id)
}

79. G E N E R AT O R S

80. FIBER
SCHEDULER + CONTINUATION
Thread Fiber
Strand

81. FIBER INTERFACE
Fiber.schedule(Executor executor, Callable callable)

82. G A I N S

83. T H R E A D S - ~ 1 M B

84. F I B E R - ~ 1 K B

85. N O M O R E T H R E A D P O O L S

86. L A C K O F C O M M O N A B S T R A C T I O N

87. D R A W B A C K S

88. L A C K O F J N I S U P P O R T

89. C A N N O T S U S P E N D U N D E R L O C K

90. T H R E A D L O C A L

91. INSTALLATION STEPS
ONLY FOR JAVA => 11
hg clone http://hg.openjdk.java.net/loom/loom
cd loom
hg update -r fibers
sh configure
make images

92. D O N E W H E N I T ’ S D O N E

93. 1 0 M I N U T E S B E F O R E M E E T U P

94. S O U R C E S
http://cr.openjdk.java.net/~rpressler/loom/Loom-Proposal.html
https://www.youtube.com/watch?v=YrrUCSi72E8
KOTLINCONF 2017 - DEEP DIVE INTO COROUTINES ON JVM BY ROMAN ELIZAROV
https://www.youtube.com/watch?v=vbGbXUjlRyQ
PROJECT LOOM: FIBERS AND CONTINUATIONS FOR JAVA BY ALAN BATEMAN
PROJECT LOOM: FIBERS AND CONTINUATIONS FOR THE JAVA VIRTUAL MACHINE

95. GQ U E S T I O N S ?