Implementing Quality                         on Java projects                           Vincent Massol                    ...
Vincent Massol            • Speaker Bio               •       CTO XWiki SAS            • Your Projects               •    ...
What is Quality?Sunday, March 31, 13
The XWiki project in summary      •      9 years old      •      28 active             committers      •      7 committers...
Examples of Quality actions            • Coding rules (Checkstyle, ...)    • Ensure API stability            • Test covera...
Quality Tip #1                       API Stability                                        27 au 29 mars 2013Sunday, March ...
The Problem                       Class Not Found or Method Not                                   FoundSunday, March 31, 13
API Stability - Deprecations     /**      * ...      * @deprecated since 2.4M1 use {@link #transform(      *             B...
API Stability - CLIRR (1/2)     <plugin>       <groupId>org.codehaus.mojo</groupId>       <artifactId>clirr-maven-plugin</...
API Stability - CLIRR (2/2)        Example from XWiki 5.0M1 Release notesSunday, March 31, 13
API Stability - Internal Package                       Javadoc                       <plugin>                         <gro...
API Stability - Legacy Module                            Aspect Weaving                             <plugin>              ...
API Stability - Young APIs     /**       * ...       * @since 5.0M1       */     @Unstable(<optional explanation>)     pub...
API Stability - Next steps            • Annotation or package for SPI?            • Better define when to use the @Unstable...
Quality Tip #2                         JAR Hell                                        27 au 29 mars 2013Sunday, March 31,...
The Problem                       Class Not Found or Method Not                        Found or not working featureSunday,...
No duplicate classes @ runtime     <plugin>       <groupId>com.ning.maven.plugins</groupId>       <artifactId>maven-duplic...
Surprising results...            • Commons Beanutils bundles some classes from Commons                   Collections, appa...
Maven: dependency version issue     <dependencies>       <dependency>                                Will run logback 0.9....
Maven: ensure correct version     <plugin>       <groupId>org.apache.maven.plugins</groupId>       <artifactId>maven-enfor...
Quality Tip #3                       Test Coverage                                        27 au 29 mars 2013Sunday, March ...
The Problem                       More bugs reported, overall quality                        goes down and harder to debug...
Use Jacoco to fail the build     <plugin>       <groupId>org.jacoco</groupId>       <artifactId>jacoco-maven-plugin</artif...
Strategy            • When devs add code (and thus tests),                   increase the TPC percentage            •     ...
Quizz Time!    Step 1: Building on my local machine gives the following:     [INFO] --- jacoco-maven-plugin:0.6.2.20130203...
Quizz Answer    ... because the JVM is non deterministic!     private Map componentEntries = new ConcurrentHashMap();     ...
Quality Tip #4                       Functional Testing Stability                             (with Jenkins)              ...
The Problem                        Too many false positives leading to                       developers not paying attenti...
False positives examples         • The JVM has crashed         • VNC is down (we run Selenium tests)         • Browser cra...
Step 1: Groovy PostBuild Plugin (1/2)     def messages = [       [".*A fatal error has been detected by the Java Runtime E...
Step 1: Groovy PostBuild Plugin (2/2)     ... continued from previous slide...     if (!shouldSendEmail) {       def pa = ...
Step 2: Mail Ext Plugin    Pre-send Script     import hudson.model.*     build.actions.each { action ->       if (action i...
Results             + use the Scriptler plugin to automate configuration for all jobsSunday, March 31, 13
Quality Tip #5                       Bug Fixing Day                                        27 au 29 mars 2013Sunday, March...
The Problem                        Bugs increasing, even simple to fix                       ones, devs focusing too much o...
Bug Fixing Day         • Every Thursday         • Goal is to close the max number of bugs         • Triaging: Can be close...
ResultsSunday, March 31, 13
Conclusion                                    27 au 29 mars 2013Sunday, March 31, 13
Parting words            • Slowly add new quality check over time            • Everyone must be on board            • Favo...
Be proud of your Quality!                          “I have offended God and                       mankind because my work ...
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Implementing Quality on Java projects

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Gives 5 hands on tips on how to improve a specific aspect of Quality on Java projects

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Implementing Quality on Java projects

  1. 1. Implementing Quality on Java projects Vincent Massol Committer XWiki XWiki SAS @vmassol 27 au 29 mars 2013Sunday, March 31, 13
  2. 2. Vincent Massol • Speaker Bio • CTO XWiki SAS • Your Projects • XWiki (community-driven open source project) • Past: Maven, Apache Cargo, Apache Cactus, Pattern Testing • Other Credentials: • LesCastCodeurs podcast • Creator of OSSGTP open source group in Paris • 3 books: JUnit in Action, Maven: A Developer’s Notebook, BBWMSunday, March 31, 13
  3. 3. What is Quality?Sunday, March 31, 13
  4. 4. The XWiki project in summary • 9 years old • 28 active committers • 7 committers do 80% of work • 700K NCLOC • 11 commits/ day • 16 mails/daySunday, March 31, 13
  5. 5. Examples of Quality actions • Coding rules (Checkstyle, ...) • Ensure API stability • Test coverage • Code reviews • Track bugs • License header checks • Don’t use Commons Lang 2.x • Release with Java 6 • Use SLF4J and don’t draw Log4J/ • Ensure javadoc exist JCL in dependencies • Prevent JAR hell • Automated build • Release often (every 2 weeks) • Automated unit tests • Collaborative design • Stable automated • Test on supported functional tests environments (DB & Browsers)Sunday, March 31, 13
  6. 6. Quality Tip #1 API Stability 27 au 29 mars 2013Sunday, March 31, 13
  7. 7. The Problem Class Not Found or Method Not FoundSunday, March 31, 13
  8. 8. API Stability - Deprecations /** * ... * @deprecated since 2.4M1 use {@link #transform( * Block, TransformationContext)} */ @Deprecated void transform(XDOM dom, Syntax syntax) throws TransformationException;Sunday, March 31, 13
  9. 9. API Stability - CLIRR (1/2) <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <configuration> <ignored> <difference> <differenceType>7006</differenceType> <className>org/xwiki/.../MetaDataBlock</className> <method>org.xwiki....block.Block clone()</method> <to>org.xwiki.rendering.block.MetaDataBlock</to> <justification>XDOM#clone() doesnt clone the meta data</justification> </difference> ...Sunday, March 31, 13
  10. 10. API Stability - CLIRR (2/2) Example from XWiki 5.0M1 Release notesSunday, March 31, 13
  11. 11. API Stability - Internal Package Javadoc <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-javadoc-plugin <configuration> <excludePackageNames>*.internal.* </excludePackageNames> CLIRR <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <excludes> <exclude>**/internal/**</exclude> <exclude>**/test/**</exclude>Sunday, March 31, 13
  12. 12. API Stability - Legacy Module Aspect Weaving <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>aspectj-maven-plugin</...> ... <configuration> <weaveDependencies> <weaveDependency> <groupId>org.xwiki.rendering</...> <artifactId>xwiki-rendering-api</...> ... + “Legacy” ProfileSunday, March 31, 13
  13. 13. API Stability - Young APIs /** * ... * @since 5.0M1 */ @Unstable(<optional explanation>) public EntityReference createEntityReference(String name,...) { ... } + max duration for keeping the annotation!Sunday, March 31, 13
  14. 14. API Stability - Next steps • Annotation or package for SPI? • Better define when to use the @Unstable annotation • Not possible to add a new method to an existing Interface • Java 8 and Virtual Extension/Defender methods interface TestInterface {   public void testMe();   public void newMethod() default {     System.out.println("Default from interface");   } }Sunday, March 31, 13
  15. 15. Quality Tip #2 JAR Hell 27 au 29 mars 2013Sunday, March 31, 13
  16. 16. The Problem Class Not Found or Method Not Found or not working featureSunday, March 31, 13
  17. 17. No duplicate classes @ runtime <plugin> <groupId>com.ning.maven.plugins</groupId> <artifactId>maven-duplicate-finder-plugin</artifactId> <executions> <execution> <phase>verify</phase> <goals> <goal>check</goal> </goals> <configuration> <failBuildInCaseOfConflict>true</...> <exceptions> ...Sunday, March 31, 13
  18. 18. Surprising results... • Commons Beanutils bundles some classes from Commons Collections, apparently to avoid drawing a dependency to it... • Xalan bundles a lot of other projects (org/apache/xml/**, org/apache/ bcel/**, JLex/**, java_cup/**, org/apache/regexp/**). In addition, it even has these jars in its source tree without any indication about their versions... • stax-api, geronimo-stax-api_1.0_spec and xml-apis all draw javax.xml.stream.* classes • xmlbeans and xml-apis draw incompatible versions of org.w3c.dom.* classes 14 exceptions in total!Sunday, March 31, 13
  19. 19. Maven: dependency version issue <dependencies> <dependency> Will run logback 0.9.9 <groupId>org.slf4j</groupId> with slf4J-api 1.4.0 <artifactId>slf4j-api</artifactId> instead of 1.5.0! <version>1.4.0</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>0.9.9</version> <!-- Depends on org.slf4j:slf4j-api:1.5.0 --> </dependency> </dependencies>Sunday, March 31, 13
  20. 20. Maven: ensure correct version <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-enforcer-plugin</artifactId> <executions> <execution> <id>enforce-version-compatibility</id> <phase>verify</phase> <goals> <goal>enforce</goal> </goals> <configuration> <rules> <requireUpperBoundDeps/> </rules>Sunday, March 31, 13
  21. 21. Quality Tip #3 Test Coverage 27 au 29 mars 2013Sunday, March 31, 13
  22. 22. The Problem More bugs reported, overall quality goes down and harder to debug softwareSunday, March 31, 13
  23. 23. Use Jacoco to fail the build <plugin> <groupId>org.jacoco</groupId> <artifactId>jacoco-maven-plugin</artifactId> <executions> <execution><id>jacoco-prepare</id> <goals><goal>prepare-agent</goal></goals> </execution> <execution><id>jacoco-check</id> <goals><goal>check</goal></goals> </execution> </executions> <configuration> <check> <instructionRatio>${xwiki.jacoco.instructionRatio}</...> </check>}Sunday, March 31, 13
  24. 24. Strategy • When devs add code (and thus tests), increase the TPC percentage • Put the Jacoco check in “Quality” Maven Profile • Have a CI job to execute that profile regularly • About 15% overhead compared to build without checks • “Cheat mode”: Add easier-to-write testSunday, March 31, 13
  25. 25. Quizz Time! Step 1: Building on my local machine gives the following: [INFO] --- jacoco-maven-plugin:0.6.2.201302030002:check (jacoco-check) [INFO] All coverage checks have been met. Step 2: Building on the CI machine gave: [INFO] --- jacoco-maven-plugin:0.6.2.201302030002:check (jacoco-check) [WARNING] Insufficient code coverage for INSTRUCTION: 75.52% < 75.53% Non determinism! Why?Sunday, March 31, 13
  26. 26. Quizz Answer ... because the JVM is non deterministic! private Map componentEntries = new ConcurrentHashMap(); ... for (Map.Entry entry : componentEntries.entrySet()) { if (entry.getValue().instance == component) {   key = entry.getKey();     oldDescriptor = entry.getValue().descriptor;     break;   } }Sunday, March 31, 13
  27. 27. Quality Tip #4 Functional Testing Stability (with Jenkins) 27 au 29 mars 2013Sunday, March 31, 13
  28. 28. The Problem Too many false positives leading to developers not paying attention to CI emails anymore... leading to failing softwareSunday, March 31, 13
  29. 29. False positives examples • The JVM has crashed • VNC is down (we run Selenium tests) • Browser crash (we run Selenium tests) • Git connection issue • Machine slowness (if XWiki cannot start under 2 minutes then it means the machine has some problems) • Nexus is down (we deploy our artifacts to a Nexus repository) • Connection issue (Read time out)Sunday, March 31, 13
  30. 30. Step 1: Groovy PostBuild Plugin (1/2) def messages = [ [".*A fatal error has been detected by the Java Runtime Environment.*", "JVM Crash", "A JVM crash happened!"], [".*Error: cannot open display: :1.0.*", "VNC not running", "VNC connection issue!"], ... ] def shouldSendEmail = true messages.each { message -> if (manager.logContains(message.get(0))) { manager.addWarningBadge(message.get(1)) manager.createSummary("warning.gif").appendText(...) manager.buildUnstable() shouldSendEmail = false } }Sunday, March 31, 13
  31. 31. Step 1: Groovy PostBuild Plugin (2/2) ... continued from previous slide... if (!shouldSendEmail) { def pa = new ParametersAction([ new BooleanParameterValue("noEmail", true) ]) manager.build.addAction(pa) }Sunday, March 31, 13
  32. 32. Step 2: Mail Ext Plugin Pre-send Script import hudson.model.* build.actions.each { action -> if (action instanceof ParametersAction) { if (action.getParameter("noEmail")) { cancel = true } } }Sunday, March 31, 13
  33. 33. Results + use the Scriptler plugin to automate configuration for all jobsSunday, March 31, 13
  34. 34. Quality Tip #5 Bug Fixing Day 27 au 29 mars 2013Sunday, March 31, 13
  35. 35. The Problem Bugs increasing, even simple to fix ones, devs focusing too much on new features (i.e. scope creep) vs fixing Bugs created vs closed what existsSunday, March 31, 13
  36. 36. Bug Fixing Day • Every Thursday • Goal is to close the max number of bugs • Triaging: Can be closed with Won’t fix, Duplicate, Cannot Reproduce, etc • Close low hanging fruits in priority • Started with last 365 days then with last 547 days and currently with last 730 days (we need to catch up with 40 bugs!)Sunday, March 31, 13
  37. 37. ResultsSunday, March 31, 13
  38. 38. Conclusion 27 au 29 mars 2013Sunday, March 31, 13
  39. 39. Parting words • Slowly add new quality check over time • Everyone must be on board • Favor Active Quality (i.e. make the build fail) over Passive checks • Be ready to adapt/remove checks if found not useful enough • Quality brings some risks: • Potentially less committers for your project (especially open source) • Project seen as “less fun”Sunday, March 31, 13
  40. 40. Be proud of your Quality! “I have offended God and mankind because my work didnt reach the quality it should have.” Leonardo da Vinci, on his death bedSunday, March 31, 13
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