Building Software at Every Change - Continuous Integration - page 87

Run Fast Builds
Stopping your development activities to wait for feedback slows the
rhythm of development for everyone on the project. Consequently,
builds that take a long time to complete often cast an unfavorable
shadow over the practice of CI. Rapid feedback in CI is crucial. The
shorter the duration of the integration build, the faster you will receive
feedback.
Integration Build Scalability and Performance
Your build scalability indicates how capable your build system
is of handling an increase in the amount of code that it integrates
and analyzes. Your build performance refers to the duration of
your build. Ideally, as your code base gets larger, your CI system
should be capable of handling this increase without much degra-
dation in performance.
If developers are not committing code to a version control reposi-
tory frequently, the reason may be a slow integration build. To begin to
reduce build duration, perform a high-level analysis of the integration
build environment to determine the bottlenecks. Next, analyze the
findings and determine the most appropriate improvement, then
attempt to make changes in the build process to reduce the build's
duration. Lastly, reevaluate the build duration to determine if further
improvements are warranted.
At a high level, here is an approach you can use to diagnose and
reduce a build's duration.
1. Gather build metrics.
2. Analyze build metrics.
3. Choose and perform improvements.
4. Reevaluate; repeat if necessary.