Simpler Concurrency, Scalability & Fault-tolerance through …assets.en.oreilly.com/1/event/45/Akka_...

Akka:Simpler Concurrency, Scalability &

Fault-tolerance through Actors

Jonas Bonér@jboner

Tuesday, July 20, 2010

•Writing correct concurrent

applications is too hard

•Scaling out applications is

too hard

•Writing highly fault-tolerant

applications is too hard

We believe that...


It doesn’t have to

be like this

We need to raise the abstraction level


Locks & Threads

are...


...sometimes

plain evil


...but always the

wrong default


“Threads are to Concurrency as Witchcraft is to Physics”

“Hanging by a thread is the punishment for Shared State Concurrency”

- Gilad Bracha


Actorsone tool in the toolbox


• Implements Message-Passing Concurrency

• Share!NOTHING

• Isolated lightweight processes

•Communicates through messages

•Asynchronous and non-blocking

• Each actor has a mailbox (message queue)

Actor Model of Concurrency


Actor Model of Concurrency

• Easier to reason about

• Raised abstraction level

• Easier to avoid

–Race conditions

–Deadlocks

–Starvation

–Live locks


Introducing

STM

Persistent

Distributed

RESTful Secure

Agents

Dataflow Open Source

Actors


ARCHITECTURE

CORE

SERVICES


ARCHITECTURE

ADD-ON

MODULES


ARCHITECTURE

ENTERPRISE

MODULES


Akka Actors


Two different models

• Thread-based

• Event-based

– Very!lightweight (600 bytes per actor)

– Can easily create!millions!on a single workstation (6.5 million on 4 G RAM)

– Does not consume a thread


!"#$%&'($!)!"#$%

!*"##!&'()*+,!$+)$,-#!-$*',!.

!!./01")$!1"/!$'()*+,!/!0

!!-$2!,+$+#1+!/!.

!!!!!"#$!"#$%!/2!

!!!!!!$'()*+,!3/!4

!!!!!!5,#)*6)7$'()*+,8

!!9

9

Actors


03.&/)!-$*',:;

1"*!$'()*+,!/!<$*',=>?&'()*+,@

Create Actors

$'()*+, is an -$*',A+>


1"*!<$*',!/!<$*',=>7,$4!BC-$*',7::88

Create Actors

create actor with constructor arguments


1"*!$'()*+,!/!<$*',=>?&'()*+,@

$'()*+,:D*<,*

Start actors


1"*!$'()*+,!/!<$*',=>?&'()*+,@:D*<,*

Start actors


1"*!$'()*+,!/!<$*',=>?&'()*+,@:D*<,*

$'()*+,:D*'5

Stop actors


!*"##%BC-$*',!$+)$,-#!-$*',!.

%%&1$//0-$%-$2!#)#*!/!.

!!!!:::!EE!$<66+F!<>*+,!GD*<,*H!

!!9

!!&1$//0-$%-$2!DI(*F'J)!/!.

!!!!:::!EE!$<66+F!K+>',+!GD*'5H

!!9

9

init & shutdown callbacks


!*"##!A+$(,D#1+-$*',!$+)$,-#!-$*',!.

!!./01")$!1"/!$'()*+,!/!0

!!D+6>:#F!/!LD+,1#$+M,+$(,D#1+N

!!-$2!,+$+#1+!/!.

!!!!!"#$!"#$%!/2!

!!!!!!$'()*+,!3/!4

!!!!!!D+6>!O!"#$%

!!9

9

the self reference


1"*%J',%+,!/!<$*',!.

!!!"#$!P',%7>)8!/2!>)78

9

Actorsanonymous


$'()*+,!O!"#$%!

Send: !

fire-forget


1"*!,+D(6*!/!7<$*',!OO!B+DD<Q+8:<D?R*,#)Q@

Send: !!

uses Future under the hood (with time-out)


1"*!,+D(6*=5*#')!/!<$*',!OO!B+DD<Q+

1"*!,+D(6*!/!,+D(6*=5*#')

!!!!!!!!!!!!:Q+*=,S6D+7F+><(6*A+D(6*8

1"*!,+D(6*!/!,+D(6*=5*#'):Q+*=,S6D+7

!!!!)5/&4%,$4!ST$+5*#')7L"#U+F!'(*N888

Send: !!

returns an Option[ResultType] directly


EE!,+*(,)D!<!>(*(,+

1"*!>(*(,+!/!<$*',!OOO!B+DD<Q+

>(*(,+:<J<#*

1"*!,+D(6*!/!>(*(,+:Q+*

:::

V(*(,+D:<J<#*=)+7W#D*7>(*4X!>(*YX!:::88

V(*(,+D:<J<#*-667W#D*7>(*4X!>(*YX!:::88

Send: !!!

returns the Future directly


!*"##!R'U+-$*',!$+)$,-#!-$*',!.

!!-$2!,+$+#1+!/!.

!!!!!"#$!ZD+,7)<U+8!/2!

!!!!!!EE!(D+!,+56C

!!!!!!D+6>:,+56C7L[#!N!3!)<U+8

!!9

9

Reply


!*"##!R'U+-$*',!$+)$,-#!-$*',!.

!!-$2!,+$+#1+!/!.

!!!!!"#$!ZD+,7)<U+8!/2!

!!!!!!EE!D*',+!<J<C!*I+!D+)F+,

!!!!!!EE!*'!(D+!6<*+,!',!

!!!!!!EE!D'U+JI+,+!+6D+

!!!!!!:::!/!D+6>:D+)F+,

!!9

9

Reply


!*"##!R'U+-$*',!$+)$,-#!-$*',!.

!!-$2!,+$+#1+!/!.

!!!!!"#$!ZD+,7)<U+8!/2!

!!!!!!EE!D*',+!<J<C!*I+!D+)F+,!>(*(,+

!!!!!!EE!*'!,+D'61+!6<*+,!',!

!!!!!!EE!D'U+JI+,+!+6D+

!!!!!!:::!/!D+6>:D+)F+,V(*(,+

!!9

9

Reply


EE!F+>#)+!*I+!$<D+!$6<DD

!"#$%!*"##!A+Q#D*+,7(D+,M!ZD+,8

EE!$,+<*+!<)F!D+)F!<!)+J!$<D+!$6<DD!U+DD<Q+

<$*',!O!A+Q#D*+,7(D+,8

EE!*(56+D

<$*',!O!7(D+,)<U+X!5<DDJ',F8

EE!6#D*D

<$*',!O!W#D*7LK#66NX!LK'KNX!L<6#$+N8

Good immutable messages


Akka Dispatchers


&'($!)!\#D5<*$I+,D!.

!!-$2!)+JST+$(*',]<D+FS1+)*\,#1+)\#D5<*$I+,7)<U+M!R*,#)Q8

!!-$2!)+JST+$(*',]<D+FS1+)*\,#1+)P',%R*+<6#)Q\#D5<*$I+,7)<U+M!R*,#)Q8

!!-$2!)+J"I,+<F]<D+F\#D5<*$I+,7<$*',M!-$*',A+>8

!!

!!-$2!)+JA+<$*',]<D+F"I,+<F^''6S1+)*\,#1+)\#D5<*$I+,7)<U+M!R*,#)Q8

!!-$2!)+JA+<$*',]<D+FR#)Q6+"I,+<FS1+)*\,#1+)\#D5<*$I+,7)<U+M!R*,#)Q8

9

Dispatchers


!*"##!BC-$*',!$+)$,-#!-$*',!.

!!D+6>:F#D5<*$I+,!/!\#D5<*$I+,D

!!!!:)+J"I,+<F]<D+F\#D5<*$I+,7D+6>8

!!

!!:::

9

<$*',:F#D5<*$I+,!/!F#D5<*$I+,!EE!K+>',+!D*<,*+F

Set dispatcher


1"*!F#D5<*$I+,!/

!!\#D5<*$I+,D:)+JST+$(*',]<D+FS1+)*\,#1+)\#D5<*$I+,

F#D5<*$I+,!!!!

!!!!:J#*I_+J"I,+<F^''6P#*I]'()F+F]6'$%#)Q`(+(+74008

!!!!:D+*&',+^''6R#a+74b8

!!!!:D+*B<T^''6R#a+74Yc8

!!!!:D+*d++5-6#1+"#U+e)B#66#D7b00008

!!!!:D+*A+f+$*#')^'6#$C7,$4!&<66+,A()D^'6#$C8

!!!!:K(#6F"I,+<F^''6

EventBasedDispatcherFluent DSL


MessageQueues

• Unbounded LinkedBlockingQueue• Bounded LinkedBlockingQueue• Bounded ArrayBlockingQueue

Bounded SynchronousQueue

Plus different options per queue


1"*!<$*',D!/!-$*',A+Q#D*,C:<$*',D

1"*!<$*',D!/!-$*',A+Q#D*,C:<$*',DV',?"g^S@

1"*!<$*',D!/!-$*',A+Q#D*,C:<$*',DV',7#F8

1"*!<$*',!/!-$*',A+Q#D*,C:<$*',V',7((#F8

-$*',A+Q#D*,C:>',+<$I7>)8

-$*',A+Q#D*,C:DI(*F'J)-66

ActorRegistry


Let it crash fault-tolerance


Stolen from

Erlang


9 nines


OneForOne fault handling strategy


AllForOnefault handling strategy


Supervisor hierarchies


-66V',=)+R*,<*+QC7

!!U<T_,=>A+*,#+DX!

!!J#*I#)"#U+A<)Q+8

=)+V',=)+R*,<*+QC7

!!U<T_,=>A+*,#+DX!

!!J#*I#)"#U+A<)Q+8

Fault handlers


6#)%7<$*',8!

()6#)%7<$*',8!

D*<,*W#)%7<$*',8

D5<J)W#)%?BC-$*',@

Linking


*,<5ST#*!/!W#D*7

!$6<DD=>?R+,1#$+ST$+5*#')@X!

!$6<DD=>?^+,D#D*+)$+ST$+5*#')@8

trapExit


!*"##!R(5+,1#D',!$+)$,-#!-$*',!.

!!03.&/)!D+6>:;

!!*,<5ST#*!/!W#D*7$6<DD=>?"I,'J<K6+@8

!!><(6*[<)F6+,!/!

!!!!R'U+7=)+V',=)+R*,<*+QC7hX!h00088

!!-$2!,+$+#1+!/!.

!!!!!"#$!A+Q#D*+,7<$*',8!/2!

!!!!!!6#)%7<$*',8

!!9

9

Supervision


!*"##!V<(6*"'6+,<)*R+,1#$+!$+)$,-#!-$*',!.

!!:::

!!&1$//0-$%-$2!5,+A+D*<,*7,+<D')M!"I,'J<K6+8!/!.

!!!!:::!EE!$6+<)!(5!'$2&/$!,+D*<,*

!!9

!!&1$//0-$%-$2!5'D*A+D*<,*7,+<D')M!"I,'J<K6+8!/!.

!!!!:::!EE!#)#*!"2)$/!,+D*<,*

!!9

9

Manage failure


Remote Actors


EE!(D+!I'D*!i!5',*!#)!$')>#Q

A+U'*+_'F+:D*<,*

A+U'*+_'F+:D*<,*7j6'$<6I'D*jX!kkkk8

Remote Server

Scalable implementation based on NIO (Netty) & Protobuf


•Client-initated and managed

•Server-initiated and managed

Two types of

remote actors


EE!U+*I'FD!#)!-$*',!$6<DD

D5<J)A+U'*+?BC-$*',@7I'D*X!5',*8!

D5<J)W#)%A+U'*+?BC-$*',@7I'D*X!5',*8

D*<,*W#)%A+U'*+7<$*',X!I'D*X!5',*8

Client-managedsupervision works across nodes


1"*!<$*',^,'TC!/!D5<J)W#)%A+U'*+?BC-$*',@7

!!LF<,%D*<,NX!

!!kkkk8

<$*',^,'TC!O!U+DD<Q+

Client-managedmoves actor to server

client manages through proxy


A+U'*+_'F+:,+Q#D*+,7

!!LD+,1#$+M#FNX!<$*',=>?BCR+,1#$+@8

Server-managedregister and manage actor on server

client gets “dumb” proxy handle

server part


1"*!I<)F6+!/!A+U'*+&6#+)*:<$*',V',7

!!LD+,1#$+M#FNX!

!!LF<,%D*<,NX!

!!kkkk8

I<)F6+!O!U+DD<Q+

Server-managed

client part


&6(D*+,:,+6<CB+DD<Q+7

!!$6<DD=>?"C5+=>-$*',@X!U+DD<Q+8

2&/%7+)F5'#)*!lm!&6(D*+,8!

!!D5<J)A+U'*+?"C5+=>-$*',@7!!

!!!!!!!!!!!!!!+)F5'#)*:I'D*X!

!!!!!!!!!!!!!!+)F5'#)*:5',*8

Cluster Membership


STManother tool in the toolbox


60

What is STM?


STM: overview• See the memory (heap and stack) as a transactional dataset

• Similar to a database

• begin

• commit

• abort/rollback

• Transactions are retried automatically upon collision

• Rolls back the memory on abort


• Separates Identity from Value

- Values are immutable

- Identity (Ref) holds Values

•Change is a function

•Compare-and-swap (CAS)

•Abstraction of time

•Must be used within a transaction

Managed References


1"*!,+>!/!A+>7B<5?R*,#)QX!ZD+,@788

1"*!(D+,D!/!,+>:Q+*

1"*!)+JZD+,D!/!(D+,D!3!7LK#66N!m2!ZD+,7LK#66N88

,+>:DJ<57)+JZD+,D8

Managed References


1"*!(D+,D!/!",<)D<$*#')<6B<5?R*,#)QX!ZD+,@78

1"*!(D+,D!/!",<)D<$*#')<6n+$*',?ZD+,@78

Transactionaldatastructures


03.&/)!",<)D<$*#'):W'$<6:;

<*'U#$!.

!!:::

!!<*'U#$!.!EE!)+D*+F!*,<)D<$*#')D!$'U5'D+

!!!!:::!EE!F'!D'U+*I#)Q!J#*I#)!<!*,<)D<$*#')

!!9

9

STM: API


Actors + STM = Transactors


!*"##!ZD+,A+Q#D*,C!$+)$,-#!",<)D<$*',!.

!!

!!./01")$%1"*!D*',<Q+!/!

!!!!",<)D<$*#')<6B<5?R*,#)QX!ZD+,@78

!!-$2!,+$+#1+!/!.

!!!!!"#$!_+JZD+,7(D+,8!/2

!!!!!!D*',<Q+!3!7(D+,:)<U+!m2!(D+,8

!!!!:::!

!!9

9

Transactors


Transactors


TransactorsStart transaction



Send message



Send message

Update statewithin transaction



Send message

Update statewithin transaction

Transaction fails


Transactors


TransactorsTransactionautomatically

retried


Agentsyet another tool in the toolbox


1"*!<Q+)*!/!-Q+)*7h8

EE!D+)F!>()$*#')!<DC)$I,')'(D6C

<Q+)*!D+)F!7;!3!48!

1"*!,+D(6*!/!<Q+)*78!EE!F+,+>

:::!EE!(D+!,+D(6*

<Q+)*:$6'D+

Agents

Cooperates with STMTuesday, July 20, 2010

(some of the) Modules


Akka Spring


lK+<)D2

!!l<%%<M<$*#1+m'Kf+$*!#F/jUC-$*#1+=Kf+$*j!

!!!!!!!!!!!!!!!!!!!!!!*<,Q+*/j$'U:K#a:BC^=o=j!

!!!!!!!!!!!!!!!!!!!!!!*,<)D<$*#')<6/j*,(+j!

!!!!!!!!!!!!!!!!!!!!!!*#U+'(*/j4000j!E2

!!:::

lEK+<)D2

Spring integration


6<%%<MD(5+,1#D#')!#F7jUCmD(5+,1#D',j8

!!6<%%<M,+D*<,*9D*,<*+QC!><#6'1+,7j-66V',=)+j!

!!!!!!!!!!!!!!!!!!!!!!!!!,+*,#+D7jpj!

!!!!!!!!!!!!!!!!!!!!!!!!!*#U+,<)Q+7j4000j8

!!!!6<%%<M*,<59+T#*D8

! !!6<%%<M*,<59+T#*8f<1<:#':e=ST$+5*#')6;<%%<M*,<59+T#*8

!!!!6;<%%<M*,<59+T#*D8

!!6;<%%<M,+D*<,*9D*,<*+QC8

!!6<%%<M<$*#1+9'Kf+$*D8

!!!!6<%%<M<$*#1+9'Kf+$*!*<,Q+*7j$'U:K#a:BC^=o=j!

!!!!!!!!!!!!!!!!!!!!!!!!6#>+$C$6+7j5+,U<)+)*j!

!!!!!!!!!!!!!!!!!!!!!!!!*#U+'(*7j4000j8

!!!!!!6<%%<M,+D*<,*9$<66K<$%D!5,+7j5,+A+D*<,*j!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!5'D*7j5'D*A+D*<,*j;8

!!!!6;<%%<M<$*#1+9'Kf+$*8

!!6;<%%<M<$*#1+9'Kf+$*D8

6;<%%<MD(5+,1#D#')8

Spring integration


Akka Camel


!*"##!BC&')D(U+,!$+)$,-#!-$*',!40)5!&')D(U+,!.

!!-$2!+)F5'#)*Z,#!/!j>#6+MF<*<E#)5(*j

!

!!-$2!,+$+#1+!/!.

!!!!!"#$!UDQM!B+DD<Q+!/2!

!!!!!!6'Q:#)>'7j,+$+#1+F!qDj!>',U<*

!!!!!!UDQ:K'FC-D7$6<DD=>?R*,#)Q@88

!!9

9

Camel: consumer


!*"##!BC&')D(U+,!$+)$,-#!-$*',!40)5!&')D(U+,!.

!!-$2!+)F5'#)*Z,#!/!

!!!!jf+**CMI**5MEE0:0:0:0MccrrE$<U+6E*+D*j

!

!!-$2!,+$+#1+!/!.

!!!!!"#$!UDQM!B+DD<Q+!/2!

!!!!!!,+56C7j[+66'!qDj!>',U<*!

!!!!!!!!!!!!UDQ:K'FC-D7$6<DD=>?R*,#)Q@88

!!9

9

Camel: consumer


http://0.0.0.0:8877/camel/test1

http://0.0.0.0:8877/camel/test1

!*"##!&'U+*^,'F($+,!

!!$+)$,-#!-$*',!40)5!^,'F($+,!.

!!

!!-$2!+)F5'#)*Z,#!/!

!!!!j$'U+*FMEE6'$<6I'D*Mc444E*+D*j

9

Camel: producer


1"*!5,'F($+,!/!<$*',=>?&'U+*^,'F($+,@:D*<,*

1"*!*#U+!/!j&(,,+)*!*#U+M!j!3!,$4!\<*+

5,'F($+,!O!*#U+

Camel: producer


Akka Persistence


Akka Persistence API

EE!*,<)D<$*#')<6!&<DD<)F,<mK<$%+F!B<5!

1"*!U<5!/!&<DD<)F,<R*',<Q+:)+JB<5

EE!*,<)D<$*#')<6!A+F#DmK<$%+F!n+$*',!

1"*!1+$*',!/!A+F#DR*',<Q+:)+Jn+$*',

EE!*,<)D<$*#')<6!B')Q'mK<$%+F!A+>

1"*!,+>!/!B')Q'R*',<Q+:)+JA+>

Turns the STM into ACID


Get data by id

EE!*,<)D<$*#')<6!&<DD<)F,<mK<$%+F!B<5!

1"*!U<5!/!&<DD<)F,<R*',<Q+:Q+*B<57((#F8

EE!*,<)D<$*#')<6!A+F#DmK<$%+F!n+$*',!

1"*!1+$*',!/!A+F#DR*',<Q+:Q+*n+$*',7((#F8

EE!*,<)D<$*#')<6!B')Q'mK<$%+F!A+>

1"*!,+>!/!B')Q'R*',<Q+:Q+*A+>7((#F8


For Redis only (so far)

1"*!s(+(+M!^+,D#D*+)*`(+(+?S6+U+)*"C5+@!/!!!

!!A+F#DR*',<Q+:)+J`(+(+

1"*!D+*M%^+,D#D*+)*R',*+FR+*?S6+U+)*"C5+@!/

!!A+F#DR*',<Q+:)+JR',*+FR+*


Akka Deployment


Deploy as dependency JAR in WEB-INF/lib etc.

Run as microkernel

Soon OSGi-enabled, then drop in any OSGi container (Spring DM server, Karaf etc.)

Deployment


REST

Comet

Security

...and much more

Web

GuiceJTA

AMQP


Learn morehttp://akkasource.org


http://jonasboner.com/

http://jonasboner.com/

EOFTuesday, July 20, 2010

?Tuesday, July 20, 2010

Simpler Concurrency, Scalability & Fault-tolerance through …assets.en.oreilly.com/1/event/45/Akka_...

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