CloudBees Build Acceleration includes a dependency optimization feature to improve performance. By learning which dependencies are actually needed for a build, CloudBees Build Acceleration can use that information to improve performance in subsequent builds.
When dependency optimization is enabled, eMake maintains a dependency information file for each makefile. If a build’s dependencies have not changed from its previous build, eMake can use that stored dependency information file for subsequent builds.
Enabling dependency optimization
You must first run a "learning" build with the dependency optimization feature enabled. To enable dependency optimization, set the following: --emake-optimize-deps=1
For the learning build, (because there is no stored dependency information file for that specific makefile) the argument only saves a new result. For subsequent builds, the argument enables the reuse of stored dependency information and saves a new file as appropriate. If you do not specify --emake-optimize-deps=1, then dependency information is not saved or accessed.
The following table describes dependency optimization-related options.
| eMake Option | Description |
|---|---|
--emake-assetdir=< path > |
Use the specified directory for assets such as saved dependency information. The default directory is named |
--emake-optimize-deps= < 0/1 > |
Use the saved dependency information file for a makefile when dependencies are the same and save new dependency information when appropriate. |
Dependency optimization file location and naming
Dependency information files are saved in the working directory where eMake was invoked under <assetdir>/deps. (The default asset directory is .emake.) The file is named from the MD5 hash of the root-relative path of the "main" makefile for the make instance that the dependency information file belongs to. For example:
-
If your eMake root is
/tmp/src, and your makefile is/tmp/src/Makefile, then the dependency information file is named after the MD5 hash of the string "Makefile". -
If your root is
/tmp/srcand your makefile is/tmp/src/foo/Makefile, the file is named after the MD5 hash of the string "foo/Makefile".