Developer Productivity Engineering: What’s in it for Java Developers?

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Dennis Ott Photography CC BY-NC-SA 2.0 https://www. ickr.com/photos/dennisott/4836474830/in/photostream/ Developer Productivity Engineering fl What’s in it for Java Developers? Brian Demers Developer Advocate Gradle BrianDemers bdemers

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Who is this guy? @BrianDemers | bdemers

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source: Silicon Valley @BrianDemers | bdemers

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VS @BrianDemers | bdemers

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VS @BrianDemers | bdemers

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Developer Productivity Engineering @BrianDemers | bdemers

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@BrianDemers | bdemers

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Code Code Wait Time for Local Build Debug Build Failure Lunch Code Sprint Wait Time for Local Build Waiting time for CI Build Investigate/Fix Flaky Tests Bottlenecks to Productivity are Everywhere

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“Bottlenecks in the toolchain are holding back the rockstar 10x developers” Pete Smoot, Software Architect, Dell Technologies It’s True at Dell, and Everywhere Else

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Developers code 52 minutes per day https://www.software.com/reports/code-time-report @BrianDemers | bdemers

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DPE is a new software development practice used by leading software development organizations to maximize developer productivity and happiness. Gradle is Pioneering DPE

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xkcd.com/303 This Doesn’t Have To Be Our Reality

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source: https://www.cshl.edu/quiz/brain-interrupted/ @BrianDemers | bdemers

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What Problems Does DPE Solve? This takes too long! This takes too long to fix This should have been observable

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Blank use will Builds background and Tests Take Tooat Long! Blank background use at will

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The anatomy and importance of fast feedback cycles PRODUCTIVITY Less idle/ wait time Less context switching More focused developers QUALITY FASTER FEEDBACK CYCLES More frequent builds KEY: Earlier quality checks Fewer downstream incidents Smaller change sets Few merge conflicts New behavior Effect KEY BENEFIT More efficient troubleshooting Faster MTTR

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Faster Builds Improve Creative Flow No. of Devs Build Time No. of local builds Team 1 Team 2 11 6 4 mins 1 mins 850 1010

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Multiple Acceleration Technologies are Best

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Build caching delivers fast build and test feedback cycles

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Build Caching ⬢ Introduced to the Java world by Gradle ⬢ Build caches are complementary to dependency caches, not mutually exclusive: in 2017 ⬢ Maven has an open source build cache ○ dependencies too ⬢ Used by leading technology ○ Can support both user local and remote caching for distributed teams A build cache accelerates building a single source repository companies like Google and Facebook ⬢ A dependency cache caches fully compiled ○ A build cache caches build actions (e.g. Gradle tasks or Maven goals)

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What is a Build Cache? Inputs ● Gradle Tasks ● Maven Goal Executions Outputs When the inputs have not changed, the output can be reused from a previous run.

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Cache Key/Value Calculation The cacheKey for Gradle Tasks/Maven Goals is based on the Inputs: cacheKey(javaCompile) = hash(sourceFiles, jdk version, classpath, compiler args) The cacheEntry contains the output: cacheEntry[cacheKey(javaCompile)] = fileTree(classFiles) For more information, see: https://docs.gradle.org/current/userguide/build_cache.html

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Remote Build Cache Savings at Dell 41% Savings from Cache

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https://reproducible-builds.org/

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fi Predictive Test Selection leads to greater ef ciencies

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https://research.facebook.com/publications/predictive-test-selection/

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Conventional Test Selection Approach

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Predictive Test Selection Approach 4% 3% 2% 2% 98% 96%

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Predictive Test Selection Savings at Dell 7 Day Period 41 Days Testing Savings Predicted

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Test distribution can make tests even faster

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How it works Autoscaler

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Existing solutions - CI fanout Test execution is distributed by manually partitioning the test set and then running partitions in parallel on several CI nodes. pipeline { stage(‘compile’) { … } parallelStage(‘test’) { step { sh ‘./gradlew :testGroup1’ } step { sh ‘./gradlew :testGroup2’ } step { sh ‘./gradlew :testGroup3’ } } } See https://builds.gradle.org/project/Gradle for an example of this strategy

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Assessment of existing solutions ⬢ Build Caching is great in many cases but doesn’t help when test inputs have changed. ⬢ Single machine parallelism is limited by that machine’s resources. ⬢ CI fanout does not help during local development, is inefficient (in particular on ephemeral CI agents or without build cache), requires manual setup and test partitioning, and result collection/aggregation

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Build Scans speeds up troubleshooting

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Improved Troubleshooting

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Build Scan - scans.gradle.com

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Without focus, problems can sneak back in… ⬢ Infrastructure changes ○ Binary management ○ Caching ○ CI agents ⬢ New annotation processors or versions of annotation processors ⬢ Build logic configurations settings ○ Build tool version and plugins ○ Compiler and/or Memory settings ⬢ Code refactoring ⬢ New office locations ⬢ Without observability, it is impossible to have a great and fast developer experience.

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“ You canBlank observe a lot by just watching.” background use at will - Yogi Berra, Catcher and Philosopher

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Performance Insights Are you tracking local build and test times?

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DPE Organizations Track Build and Test Times

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DPE Organizations Track Failure Rates

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Flaky Tests Are Everywhere 7 day period Test Flaky 299 times

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Dealing with Flaky Tests The test is flaky. What do you do now? a. Try it again b. Re-run it c. Re-run it again d. Ignore it and approve PR e. All of the above