gecko-dev/taskcluster
Gregory Szorc fbd5db6a52 Bug 1359965 - Support and generate tar.gz WPT archive; r=glandium
Several years ago there was a single zip file for all test files. Clients
would only extract the files they needed. Thus, zip was a reasonable
archive format because it allowed direct access to members without
having to decompress the entirety of the stream.

We have since split up that monolithic archive into separate,
domain-specific archives. e.g. 1 archive for mochitests and one
for xpcshell tests. This drastically cut down on network I/O
required on testers because they only fetched archives/data that
was relevant. It also enabled parallel generation of test archives,
we shaved dozens of seconds off builds due to compression being
a long pole.

Despite the architectural changes to test archive management, we
still used zip files. This is not ideal because we no longer access
specific files in test archives and thus don't care about single/partial
member access performance.

This commit implements support for generating tar.gz test archives.
And it switches the web-platform archive to a tar.gz file.

The performance implications for archive generation are significant:

before: 48,321,250 bytes; 6.05s
after:  31,844,267 bytes; 4.57s

The size is reduced because we have a single compression context
so data from 1 file can benefit compression in a subsequent file.
CPU usage is reduced because the compressor has to work less with
1 context than it does with N. While I didn't measure it, decompression
performance should also be improved for the same reasons. And of course
network I/O will be reduced.

mozharness consumers use a generic method for handling unarchiving.
This method automagically handles multiple file extensions. So as long
as downstream consumers aren't hard coding ".zip" this change should
"just work."

MozReview-Commit-ID: LQa5MIHLsms

--HG--
extra : rebase_source : 19ec875917546abc147b234a815e1a64c204b92a
2017-05-08 17:19:05 -07:00
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