Use BufferedInputStream to read from a tar file by mishail · Pull Request #402 · docker-java/docker-java
During my testing I've found that building an image with a fairly big context took a lot of time (several minutes) with docker-java. On the other hand, docker CLI was able to upload the very same context with the very same Dockerfile in 10-20 seconds.
After some profiling I've found out that we spent most time trying to read from a context's tar file, and it turned out we didn't use BufferedInputStream around FileInputStream.
Without the fix it took ~5 min to upload a ~153Mb context:
time="2015-12-14T20:27:45.165799084Z" level=info msg="POST /build?dockerfile=/Users/mikhail/.ahub/test_local/Dockerfile.sor.local&t=athena/sor:local"
time="2015-12-14T20:32:51.945725887Z" level=debug msg="[BUILDER] Use cached version: &{[/bin/sh -c #(nop) ENV JAVA_HOME=/usr/lib/jvm/jre/]}"
And with the fix it takes ~20 sec:
time="2015-12-14T20:34:52.298037218Z" level=info msg="POST /build?dockerfile=/Users/mikhail/.ahub/test_local/Dockerfile.sor.local&t=athena/sor:local"
time="2015-12-14T20:35:13.645568956Z" level=debug msg="[BUILDER] Use cached version: &{[/bin/sh -c #(nop) ENV JAVA_HOME=/usr/lib/jvm/jre/]}"