As you know bnd always produces a .jar file per bundle as its build output, and .jar files are actually zip files. And zip files can be used with and without compression.
I just found a simple way to speed up performance of builds, by using the -compression instruction to disable compression.
This can be used to control whether the .jar files bnd produces are compressed or not.
- DEFLATE: (default) compression is enabled
- STORE: no compression
Using STORE for no compression saves CPU cycles needed to compress the files.
I have now put the following into our cnf/build.bnd:
-compression: ${if;${driver;eclipse};STORE;DEFLATE}
This means that in Eclipse IDE when you are developing you will use STORE (no compression = faster, but bigger files). In all other builds (e.g. Maven, Gradle, Tycho etc. you will use DEFLATE (compressed, slower, smaller files). It uses the ${if} macro and the ${driver} macro.
The idea behind this tuning is my assumption , that locally in Eclipse you do not care about compression and thus larger files are acceptable, but instead you want things to be fast.
Impact
I did some poor mans measurements to give you an impression:
Full Workspace refresh
Doing a full workspace refresh rebuilds everything in your workspace:
-compression: DEFLATE: 70 seconds (avg)
-compression: STORE: 57s seconds (avg)
STORE was around 16-19% faster.
web-templates bundle
This bundle contains little java code, but lots of files (web templates, images etc.) which are copied to the .jar file.
I did 3 runs.
DEFLATE:
filesize: 9.459.121 bytes
BUILD FULL web-templates 1 file was built in 1.257 sec
BUILD FULL web-templates 1 file was built in 1.304 sec
BUILD FULL web-templates 1 file was built in 1.252 sec
STORE:
filesize: 28.791.742 bytes
BUILD FULL web-templates 1 file was built in 0.576 sec
BUILD FULL web-templates 1 file was built in 0.611 sec
BUILD FULL web-templates 1 file was built in 0.611 sec
STORE is > 50% faster.
core-services bundle
This bundle contains a lot of java files, but little other files.
DEFLATE
BUILD FULL core-services 1 file was built in 5.317 sec
BUILD FULL core-services 1 file was built in 5.446 sec
BUILD FULL core-services 1 file was built in 5.610 sec
STORE
BUILD FULL core-services 1 file was built in 4.687 sec
BUILD FULL core-services 1 file was built in 4.687 sec
BUILD FULL core-services 1 file was built in 4.736 sec
STORE is about 12% faster.
Conclusion
I think this is a reasonable speed up in build performance during developing OSGi bundles in the IDE with bndtools / bnd, where waiting time matters a lot, while filesize often is not that important.
Of course, it depends a little bit on the size of your workspace and the contents of your bundle. But I think this is a reasonable little trick to feel better pressing Cmd + s and drink less coffee 