Model-based Feedback for Software Performance Improvement

(1)

Progetto PRIN PaCo (Performability-aware Computing)

Lucca, 25-26 giugno 2009

Model-based Feedback for

Software Performance Improvement

PhD student

Catia Trubiani

Advisor

Vittorio Cortellessa

Dipartimento di Informatica

Università degli studi di L’Aquila

Progetto PRIN PaCo (Performability-aware Computing)

Roadmap

»

_Motivation

»

_{Software Performance Analysis Process}

»

_{Our approaches}

»

_{Related work}

(2)

3

Lucca, 25-26 giugno 2009

Motivation

»

_{What to change to improve the software design?}

C

₂

C

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Architectural

Model

Requirements:

responseTime = 8sec

…

C

₂

’

C

₁

C

₂

’’

responseTime = 7sec

C

₂

C

₁

responseTime = 10sec

performance

analysis

C

₂

’

C

₂

’’

Software Performance Analysis Process

(annotated)

Architectural Model

Model2Model

Transformation

Performance

Model

Model Solution

Results Interpretation and

Feedback Generation

Performance

Indices

1

2

3

4 5.a

5.b

Performance

Antipatterns

5.c

6

(3)

5 A corresponding “Process”

Patient

_{Transformation}

Health

_Patient

Sick

Sickness

Analysis

Making Diagnosis and

Prescribing Treatment

Symptoms

1

2

3

4 5.a

5.b

6 »

_{Physician correspondances}

-

_{Patient -> Model}

-

_{Sick -> Performance}

-

_{Indices -> Symptoms}

(Performance) Antipatterns

»

_{W.J.Brown, R.C. Malveau, H.W. Mc Cornich III, and T.J.}

Mowbray. “Antipatterns: Refactoring Software,

Architectures, and Project in Crisis”, 1998.

»

_{What to avoid and how to solve (performance) problems!}

-

_{Look at negative features of a}

software system:

>

_{The definition includes common}

mistakes (i.e. “Bad practice”) in

software development as well as

their solutions

>

_{Conceptually similar to “Design}

Patterns”: recurring solutions to

common design problems

(4)

7 Performance Antipatterns

…

Move extensive processing so that it doesn’t impede high traffic or more important work. Extensive processing in

general impedes overall response time.

Extensive

Processing

Unbalanced

Processing

To alleviate the congestion, use the Shared Resources Principle

to minimize conflicts. At a point in execution

where only one, or a few, processes may continue

to execute.

Break large filters into more stages and combine very small

ones to reduce overhead. The slowest filter in a

“pipe and filter” architecture causes the

system to have unacceptable throughput.

“Pipe and

Filter”

Architectures

Restructure software or change scheduling algorithms to enable

concurrent execution. Processing cannot make

use of available processors.

Concurrent

Processing

Systems

One-Lane Bridge

Solution

Problem

Antipattern

»

_{C. U. Smith and L. G.Williams. “More new software performance antipatterns: Even}

more ways to shoot yourself in the foot”, 2003

Snapshot-based

Monitoring-based

Snapshot vs Monitoring

»

_{Snapshot: average values in a small interval of time}

»

_{Monitoring: multiple intervals of time (i.e., a set of}

several snapshots)

time

∆

(5)

9 Snapshot-based example

»

_{Cuncurrent Processing Systems}

Processing cannot make use of available processors.

Problem

Restructure software or change scheduling algorithms to enable

concurrent execution.

Solution

P

1

P

2

P

₃

arrivals

Monitoring-based example

»

_{One-Lane Bridge}

At a point in execution where only one, or a few, processes may

continue to execute.

Problem

To alleviate the congestion, use the Shared Resources Principle

to minimize conflicts.

(6)

11 Our Approach: Conceptual Framework

(1) Specifying

Antipatterns

(2) Detecting

Antipatterns

(3) Solving

Antipatterns

…

»

_{Main activities}

V.Cortellessa, A.Di Marco, R.Eramo, A. Pierantonio, C.Trubiani

“Approaching the model-driven generation of feedback to

remove software performance flaws”, to appear in the

proceedings of Euromicro SEAA 2009.

Contributions

»

_{(1) Specifying Antipatterns}

-

_{Structuring system elements}

-

_{Formalizing antipatterns as logical predicates on these elements}

-

_{Model-driven techniques: defining a metamodel for antipatterns}

(7)

13 Structuring system elements

»

_{Problem: software developers’ world (vocabulary) is intrinsically}

distant from performance analysts’ one.

»

_{What are the system elements needed for specifying performance}

antipatterns?

…

Structuring system elements

»

_{Different system elements of antipatterns can}

be organized into “Views”

C.M.Woodside. “A Three-View Model for Performance Engineering of concurrent software”, 1995.

Classes, components,

relationships among them,…

that contribute to model

static aspects

class

STATIC VIEW

component

client

supplier

operation

Interactions occurring between

classes, components,… that

contribute to model

dynamic aspects

DYNAMIC

VIEW

message

sender

receiver

Mapping classes, components, …

onto the hardware

resources to model

deployment aspects

DEPLOYMENT

VIEW

procesNode

queueLength

hwUtilization

Views overlapping!

…

(8)

15 Projection on system elements

class STATIC VIEW component client supplier operation DYNAMIC VIEW message sender receiver DEPLOYMENT VIEW procesNode queueLength hwUtilization

System

Service

…

Some proposals

»

_{Key Idea:}

_Neutral

_{structured data}

»

_Parametric

_{notations that can be instantiated}

with any concrete modeling notation (e.g.

UML+Marte, SPA, Aemilia, ADLs).

»

_{Notation-independent}

_approach

-

_{A first proposal: XML- b}

_{ased approach}

-

A second proposal: Model- driven approach

(9)

17 A first proposal : XML-based

»

_Neutral

_{structured data: an XML schema}

STATIC VIEW DYNAMIC VIEW DEPLOYMENT VIEW System Service

…

A first proposal : XML-based

»

_{Static View details}

(10)

19 Client/Supplier Paradigm

»

_{Flatten relations types}

Parent

Child

Whole

Part

aggregation generalization

Class A

Class B

association

client

supplier

client

supplier

…

A first proposal : XML-based

»

_{Dynamic View details}

(11)

21 A first proposal : XML-based

»

_{Deployment View details}

…

Formalizing antipatterns

»

_{Basic Idea: a performance antipattern is a logical}

predicate LP

_antipatName

»

_{A logical predicate is built with views predicates:}

StaticView predicate SP

_antipatName

, DynamicView

predicate DyP

_antipatName

, DeploymentView DeP

_antipatName

»

_{Each (static, dynamic, deployment)View predicate is}

built with a set of basic predicates BP

_i

LP

antipatName

= SVP

antipatName

∧ DyVP

antipatName

∧ DeVP

antipatName

*VP

antipatName

= *BP

1

(∧,

∧

) … (∧,

∧

) *BP

n

(12)

23 Formalizing antipatterns

»

_{How to define a basic predicate BP}

i

?

»

_{Supporting elements}

-

_{Auxiliary Functions F}

func

-

_{Thresholds Th}

threshold

>

_{System monitoring}

>

_{Heuristic evaluations}

…

Formalizing “Blob”antipattern

»

_{An example: how to formalize the performance}

antipattern “Blob”

Occurs when a single class or

component either 1) performs all

of the work of an application or

2) holds all of the applications

data. Either manifestation

results in excessive message

traffic that can degrade

performance.

Blob

Problem

Antipattern

(13)

25 Formalizing “Blob”antipattern

»

_{“Occurs when a single class or component (i.e. a software}

entity) either 1) performs all of the work of an application

or 2) holds all of the applications data”

-

_SBP

1

:∧E |

Class A

Class B

Class X

Class Y

…

F

numConnects

(E) ≥ Th

connect

auxiliary function

threshold

SVP

blob

Ξ SBP

1 …

Formalizing “Blob”antipattern

»

_“

_{Either manifestation results in excessive message traffic}

that can degrade performance.

“

-

_DyBP

1

:

Class A

Class B

Class X

Class Y

…

F

numMsgs

(E) ≥ Th

msgs

auxiliary function

threshold

DyVP

_blob

Ξ DyBP

₁

(14)

27 Formalizing “Blob”antipattern

»

_“

_{Either manifestation results in excessive message traffic}

that can degrade performance.

“

-

_DeBP

1

:

-

_DeBP

2

:

class STATIC VIEW component client supplier operation DYNAMIC VIEW message sender receiver DEPLOYMENT VIEW procesNode netUtilization hwUtilization

F

maxHwUtil

(P

E

) ≥ Th

hwUtil

F

maxNetUtil

(P

E

) ≥ Th

netUtil

_DeVP

blob

Ξ DeBP

1 ∧

DeBP

2

Class A

Class B Class X Class Y …

option

1

Class A

Class B Class X Class Y …

option

2

…

Formalizing “Blob” antipattern

»

_{Blob problem formalization}

∧E |

F

(E) ≥ Th

∧ F

(E) ≥ Th

∧

LP

blob

= SVP

blob

∧ DyVP

blob

∧ DeVP

blob

SVP

blob

Ξ SBP

1

DyVP

blob

Ξ DyBP

1

DeVP

blob

Ξ DeBP

1

∧

DeBP

2

(15)

29 A second proposal : Model-driven

»

_{Defining a metamodel for antipatterns}

-

_{APML -> AntiPattern Modeling Language}

>

_{SML -> Software Modeling Language}

>

_{SML+ -> An enrichment of SML}

>

_{RML -> Refactoring Modeling Language}

APML

SML

SML+

RML

<<refine>> <<use>>

…

Metamodel for antipatterns

»

_{An excerpt of APML}

(16)

31 Metamodel for antipatterns

»

_{Software Modeling Language SML+}

…

Static View

Dynamic View

Deployment View

Metamodel for antipatterns

»

_{Static View of SML+}

(17)

33 Metamodel for antipatterns

»

_{Dynamic View of SML+}

…

Metamodel for antipatterns

»

_{Deployment View of SML+}

(18)

35 Modeling with APML

…

»

_{An example: how to model the performance}

antipattern “Blob”

:AntipatternSpecification name= “Blob” :StaticView :DynamicView :DeploymentView :AntipatternSubview :AntipatternSubview :AntipatternSubview :AntipatternSubview swEX: SoftwareEntity swEy: SoftwareEntity Px: ProcesNode Py: ProcesNode Pz: ProcesNode :BooleanRestriction type= “or” :Message sender= swEx receiver= swEy

swResources= swEx, swEy

maxUtil = realTypeHwRes swResources= swEx swResources= swEy maxBWused = realTypeBWused numConnects= intTypeNumCons numMsgs= intTypeNumMsgs intTypeNumMsgs : intType operator= max_equal value= “$th_msgs”

Our metamodel in concrete notations

»

_{Weaving Models to drive correspondences}

between our SML+ and a concrete modeling

notation (e.g. UML + Marte).

Weaving

Model

UML +

…

(19)

37 Antipatterns in concrete notations

»

_{High-order Transformations to drive}

correspondences between the antipattern model

in our SML+ and a concrete modeling notation

(e.g. UML + Marte).

APML

SML+

AP

SML+

APML

UML + MARTE

AP

UML + MARTE

c2

T[WM(SML+,

UML+MARTE)]

…

Contributions

»

_{(2) Detecting Antipatterns}

-

Most promising antipatterns

-

Model- driven techniques: translating the occurrence of

antipatterns with OCL expressions

(20)

39 Most promising antipatterns

Software

System Model

(annotated) Software

System Model

Requirements

Antipatterns

predicates

Complete

Antipatterns

List

Violated

Requirements

Filtered

Antipatterns

List

Ranked

Antipatterns

List

New

Software

System Model

Random

Moves

Existing

Alternatives

Detection activities

…

Which ones and in what order?

…

PA

1

R

j

…

R

1

Violated

Requirements

Performance

Antipatterns

»

_{How much a Performance Antipattern PA}

i

is

important for the Violated Requirement Rj?

(21)

41 A first proposal : XML-based

»

_{Java Engine for XML parsing}

import org.w3c.dom.*;

...

Document doc = newDocumentBuilder().parse(new

File(“swSystem.xml”));

NodeList listOfProcesNodes =

doc.getElementsByTagName(“procesNode”);

System.out.println(“Total number of processors: ”

+ listOfProcesNodes.getLength());

...

Loading XML file

Creating a list of

processing nodes

Printing the number of

processing nodes

…

A second proposal : Model-driven

»

_{Translating the occurrence of}

antipatterns with OCL expressions.

(22)

43 Contributions

»

_{(3) Solving Antipatterns}

-

_{Deciding which antipatterns to solve and in what order}

-

_{Planning a simultaneous combination of antipatterns solutions}

-

_{Model-driven techniques: solving antipatterns with difference}

models

…

Analysing some problems

»

_{Requirement problems}

-

_{Functional requirement}

>

_{Legacy components cannot be split or re-deployed}

-

Non- Functional requirement

>

_{Budget limitations}

»

_{Coherency problems}

-

_{Incoherences among antipattern solutions}

(23)

45 Discussion

»

_{Further issues}

-

_{What happens if antipatterns cannot be solved due to}

(functional/non- functional) requirements?

-

What happens if feedback cannot be applied due to

incoherences between antipattern solutions?

-

_{Which is the sequential order of antipatterns rules and}

how to better drive the refactoring?

-

An antipattern solution is able to introduce an other

antipattern?

…

Simultaneous solutions

Software

System Model

Ranked

Antipatterns

List

Candidate

Moves List

New Candidate

Software

System Model

…

Acquired

Knowledge

New

Software

System Model

Observed values

on New Candidate

[1] proceed with the next move [2] learning

[3] choose the best candidate up to now

S

0

S

1

S

n

…

{PA

1

, …, PA

x

}

{PA

2

, …, PA

y

}

“Move”: application of a simultaneous

set of antipattern solutions

(24)

47 A first proposal : XML-based

»

_{Basic Idea: solving a performance antipattern by the}

negation of the logical predicate ¬LP

_antipatName

»

_{The negative logical predicate is built with the}

negation of the views predicates

»

_{Each (static, dynamic, deployment)View predicate}

has to be negated

¬

LP

antipatName

=

¬

SVP

antipatName

∧

¬

DyVP

antipatName

∧

¬

DeVP

antipatName

¬

*VP

_antipatName

=

¬

(*BP

₁

(∧,

∧

) … (∧,

∧

) *BP

_n

)

…

A first proposal : XML-based

…

LP

blob

= SVP

blob

∧ DyVP

blob

∧ DeVP

blob

SVP

blob

Ξ SBP

1

DyVP

blob

Ξ DyBP

1

DeVP

blob

Ξ DeBP

1

∧

DeBP

2

»

_{An example: “Blob” problem formalization}

(25)

49 A first proposal : XML-based

…

»

_{An example: “Blob” solution formalization}

∧

E |

F

numConnects

(E) < Th

connect

∧

F

numMsgs

(E) < Th

msgs

∧

( F

maxHwUtil

(P

E

) < Th

hwUtil

∧ F

maxNetUtil

(P

E

) < Th

netUtil

)

¬LP

blob

=

¬

(SVP

blob

∧ DyVP

blob

∧ DeVP

blob

)

¬SVP

blob

Ξ ¬SBP

1

¬DyVP

blob

Ξ ¬DyBP

1

¬DeVP

blob

Ξ ¬DeBP

1

∧

¬DeBP

2

A second proposal : Model-driven

»

_{Solving antipatterns with difference}

models.

…

Architectural

Model

Solution

1

Solution

2

Solution

m

(26)

51 Related Work

»

_{V.Cortellessa, L.Frittella, “A framework for automated generation}

of feedback from software performance analysis”, 2007.

-

_{Informal interpretation matrices from the analysis of Layered}

Queueing Networks (LQNs)

»

_{T.Parsons, J.Murphy, “Detecting Performance Antipatterns in}

component-based enterprise systems”, 2008.

-

_{Performance antipattern detection (PAD) tool for Enterprise Java}

Bean (EJB) applications

»

_{J.Xu, “Rule-based automatic software performance diagnosis and}

improvement”, 2008.

-

_{Analysis of LQNs performance model for bottlenecks and long paths}

Ongoing work

»

_{Validate the scope of the whole approach across}

languagues, to assess the indipendence of any

concrete notation.

APML

…

specification

detection

UML+Marte

Stochastic

Process

Algebras

(27)

53 Future work

»

_{Real case studies to study the usability and the}

Model-based Feedback for Software Performance Improvement

Progetto PRIN PaCo (Performability-aware Computing)

Lucca, 25-26 giugno 2009