mirror of
https://git.yoctoproject.org/poky
synced 2026-05-09 17:39:31 +00:00
Etienne Cordonnier
b643d2bc17
As discussed in https://stackoverflow.com/a/4435752/1710392 , CPython has an optimization for statements in the form "a = a + b" or "a += b". It seems that this line does not get optimized, because it has a form a = a + b + c: data = data + "./" + f.split("/./")[1] For that reason, it does a copy of data for each iteration, potentially copying megabytes of data for each iteration. Changing this line causes SignatureGeneratorBasic::get_taskhash to take 0.06 seconds instead of 45 seconds on my test setup where SRC_URI points to a big directory. Note that PEP8 recommends explicitely not to use this optimization which is specific to CPython: "do not rely on CPython’s efficient implementation of in-place string concatenation for statements in the form a += b or a = a + b" However, the PEP8 recommended form using "join()" also does not avoid the copy and takes 45 seconds in my test setup: data = ''.join((data, "./", f.split("/./")[1])) I have changed the other lines to also use += for consistency only, however those were in the form a = a + b and were optimized already. Co-authored-by: JJ Robertson <jrobertson@snap.com> (Bitbake rev: 590ae6fde9da75db3a368e5c0d47920696c33ebf) Signed-off-by: Etienne Cordonnier <ecordonnier@snap.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org> (cherry picked from commit 195750f2ca355e29d51219c58ecb2c1d83692717) Signed-off-by: Steve Sakoman <steve@sakoman.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Bitbake
=======
BitBake is a generic task execution engine that allows shell and Python tasks to be run
efficiently and in parallel while working within complex inter-task dependency constraints.
One of BitBake's main users, OpenEmbedded, takes this core and builds embedded Linux software
stacks using a task-oriented approach.
For information about Bitbake, see the OpenEmbedded website:
https://www.openembedded.org/
Bitbake plain documentation can be found under the doc directory or its integrated
html version at the Yocto Project website:
https://docs.yoctoproject.org
Contributing
------------
Please refer to
https://www.openembedded.org/wiki/How_to_submit_a_patch_to_OpenEmbedded
for guidelines on how to submit patches, just note that the latter documentation is intended
for OpenEmbedded (and its core) not bitbake patches (bitbake-devel@lists.openembedded.org)
but in general main guidelines apply. Once the commit(s) have been created, the way to send
the patch is through git-send-email. For example, to send the last commit (HEAD) on current
branch, type:
git send-email -M -1 --to bitbake-devel@lists.openembedded.org
Mailing list:
https://lists.openembedded.org/g/bitbake-devel
Source code:
https://git.openembedded.org/bitbake/
Testing:
Bitbake has a testsuite located in lib/bb/tests/ whichs aim to try and prevent regressions.
You can run this with "bitbake-selftest". In particular the fetcher is well covered since
it has so many corner cases. The datastore has many tests too. Testing with the testsuite is
recommended before submitting patches, particularly to the fetcher and datastore. We also
appreciate new test cases and may require them for more obscure issues.