Static Analysis in Search of Performance Anti-Patterns Patrycja Wegrzynowicz Founder and CTO, Yonita Inc. Founder and CTO, Yon Labs and Yon Consulting

About me Past 10+ years of professional experience as software developer, architect, and head of software R&D PhD in Computer Science (automated code analysis) Speaker at JavaOne, JavaZone, ASE, OOPSLA, Jazoon, and others Present Founder and CTO of Yonita Inc., Yon Labs, and Yon Consulting Bridge the gap between the industry and the academia Future Who cares? Seize the day!

Agenda Performance issues Performance bottlenecks and how to deal with them Automated code analysis Semantic code query system Performance anti-patterns Code samples Code queries

PERFORMANCE ISSUES

This is Java.

Is Java slow? On most Intels Java is as fast or faster than C The Gaia Satellie and Data Processing William O’Mullane from European Space Astronomy Centre Jazoon 2010

Limited Resources Hardware OS Application Locks Pools FD Threads Network Processors RAMHD Memory

Sun’s SDK, Arrays.binarySearch, Joshua Bloch

The Way We Write Software Business Requirements Technology Stack Software Teams JSF JPA hibernate strut s Tapestr y iBati s JT A EJ B RM I GWT Swin g JS P JMS aw t JND I JD O

Performance Issues Root causes Bad architecture, design, or code Wrong configuration (app/db server, OS, RDBMS) Rarely insufficient hardware Bottlenecks usually unnoticed until happen Special conditions to happen: size of data, number of users The later discovered the more expensive to solve

Performance Tuning MIF cycle Dynamic analysis Log/traces Profiles Environments Testing Production Monitor Identify Fix

Our Code

A Single Spaghetti is Hard to See

(Anti-)Patterns in Our Spaghetti

Automated Code Performance Tuning + Automated code analysis Definions of performance anti-patterns

Detection of Performance Anti-Patterns Benefits Hints on performance on higher level of abstraction (architecture, design, programming constructs) instead of in terms of lower level concepts (CPU usage, memory consumptions etc.) Supports developers and development phase Promotes best practices (refactored solutions) Problems Lack of formalization, high-level concepts, textual description Implementation variants Size of code

AUTOMATED CODE ANALYSIS Think? Why think! We have computers to do that for us. – Jean Rostand

Semantic Code Query System Code query systems Explore relationships among program elements Structural and call-related predicates CodeQuest, JQuery Semantic code query systems Focus on behavior (in-depth data flow analysis) Behavioral predicates in addition to structural ones D-CUBED – my PhD thesis (focus on design patterns) Yonita – rewrite + queries

How does Yonita work? Analyses Parser Store Query Bytecode or Sources Asm/Recoder analyses: structural, call flow, data flow transitive closures relational (MySQL) or deductive (XSB) database SQL or Prolog (anti-)patterns bugs vulnerabilities...

Metamodel Structural elements Very similar to CodeQuest and Jquery Statements Instances Symbolic instances Behavioral predicates supporting call and data flows Output and input values Assignments

Instances Null New This Parameter Exception Multiple Return Instance Param Instance This Instance New Instance Null Instance Except. Instance … … …

Behavioral Predicates Calls makesCallConditionally(Callable, Callable) makesCallAlways(Callable, Callable) Input and output values hasInput(Callable, Instance) hasInput(Statement, Instance) hasOutput(Callable, Instance) hasOutput(Statement, Instance) Assignments assigns(Field, Instance)

Running Yonita Prototype Run Yonita to parse an application yonita [classes] [libs] –prolog –mysql MySQL configuration hibernate.cfg.xml Run MySQL console and ask queries (SQL) Prolog configuration -Dprolog.file=output.P -prolog=output.P Run XSB Prolog console and ask queries (Prolog) Yonita on Google App Engine In progress

PERFORMANCE ANTI-PATTERNS

Redundant Work – Example 1 (Web)

Multiple calls to database (7 calls!) Multiple security check Each call to getUser checks permissions What if getUser were a remote method?!

Redundant Work – Example 2 (agilefant)

Redundant Work – Example 2 (agilefant – sourceforge project) Thank you hibernate! Open Session in View Session cache

Redundant Work – Example 3 (agilefant) AJAX Calls

Redundant Work – Example 3 (agilefant) AJAX Calls

Redundant Work – Example 3 (agilefant) AJAX Calls

Redundant Work Description A time-consuming method is called many times on a single execution path Consequences A slower execution time Refactored solution Call the heavy method only once and store the result for further re- use Heavy

Redundant Work – Code Query redundantWork(X, Heavy) :- // method Heavy called at least twice... method(X), method(Heavy), isHeavy(Heavy), hasChild(X, Invocation1), methodInvocation(Invocation1, Heavy), hasChild(X, Invocation2), methodInvocation(Invocation2, Heavy), //...with the same parameters setof(I1, (hasInput(Invocation1, newInstance(I1)), All), setof(I2, (hasInput(Invocation2, newInstance(I2)), All). isHeavy(X) :- isWebService(X). isHeavy(X) :- isDatabaseService(X).

Fine Grained Remote Calls Entity Beans EJB1 EJB2 Remote Calls Remote calls have significant impact on application performance Client Bean getX() getY() getZ()

One by One Processing – Example 1 Add users to a group Performed in the web layer one by one Multiple calls to the service layer Multiple loads and updates each in a separate transaction! Multiple authorization!

One by One Processing – Example 2 Delete a group Detach a group from every user in a group one by one

One by One Processing Description The objects in a collection are processed one by one and a single processing requires a call to a time-consuming method (e.g. database access, remote call) Consequences A significant increase in time with the increase of collection size Refactored solution Consider batch processing Heavy

Unused Object – Example (richfaces 3.2.2)

Unused Object Description An object created (usually retrieved from a database), passed to further methods (usually a long chain of method calls), and than not used Consequences Higher memory consumption that may lead to performance issues Refactored solution Create objects only if you need them.

Unused Objects – Hibernate Mapping

Unused Objects - Standard Collection Mapping

Unused Objects - Immutable Collection

Summary We need to write better code! Performance anti-patterns High-level concepts Many implenentation variants Static analysis can help in discovery of performance issues Useful tool but it does not replace a traditional approach to performance tuning (measure, identify, fix)

Contact Patrycja twitter.com/YonLabs Yonita