Increasing the performance of Gradle builds

Lately, I have been immersed into adding a bunch of new projects to our CI server. Although we have been using a distributed system to achieve a parallel build, at some point builds were taking a big amount of time. To put numbers: consider an scenario with 49 different projects (backend, frontend, mobile), in different branches (production, development) constantly building and deploying. There was an average waiting list to build projects of more than 20 minutes, with some projects taking more than 10 minutes to build and deploy. Something against the spirit of CI, really. After doing some research, I increased the performance of my builds in about one third. This is how to achieve it:

So with the problem detected, the next step was to find a solution: how to improve the performance of the builds. The first platform to improve was Android (15 from all our projects are Android based, which is around one third of the total). We are using Gradle build system and Android Studio. While is still great, is an on-going product with constant releases and has not reached its peak of performance yet . First, the important point was to identify the bottlenecks. I used the following script in our build.gradle file to detect which tasks were more problematic:

This code is relatively straight forward. For each task being executed by Gradle, will measure the time required, and when the build is finished will print the amount of time each task needed.

In order to perform a right benchmarking, I would use my computer with no extra program rather than the console, and run gradle clean assembleRelease. I run this in one of our ship projects with a quite typical structure for our company: a single project, containing 6 maven libraries and 2 local ones.

My first experiment shown nothing really surprising: I run gradle clean mergeReleaseResources, preDexRelease and dexRelease were the tasks more time consuming. Particularly:

Bildschirmfoto 2014-04-23 um 15.49.43

Pre-dexing is used for speeding up incremental builds. Pre-dexes dependencies of a module, so that they can just be merged together into the final dex file, but won won’t affect the release build (since you should be doing clean builds for release builds anyway). So we could get rid of this process during the release build:

While doing some research met two options to be used with gradlew:
–parallel executes parallel build for decoupled projects, leading to an increase in performance.
–daemon allows to execute our gradle as a daemon, speeding up the build time.

This options can be called from the console:

Or can be included in a gradle.properties file:

Combining all the points: I run again the same command and got the following:

Bildschirmfoto 2014-04-23 um 15.57.03

The increase in performance have been also successful in subsequent builds, and it is on average a 30% faster than the non-optimized version.

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