Joe McDonnell created IMPALA-10455:
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Summary: Reorder Maven repositories to have cleaner mirror
semantics
Key: IMPALA-10455
URL: https://issues.apache.org/jira/browse/IMPALA-10455
Project: IMPALA
Issue Type: Improvement
Components: Frontend, Infrastructure
Affects Versions: Impala 4.0
Reporter: Joe McDonnell
Using a Maven mirror to replace Maven Central can speed up the Impala build
substantially. However, the artifacts that are present in the toolchain s3
bucket are unlikely to be able to resolved by the mirror, because they are not
in Maven Central or other repositories. If the Maven mirror has a long list of
source repositories, a miss can be expensive, because it may try each of the
mirror's source repositories. It would be useful to exclude the s3 bucket Maven
repositories from the mirroring. For example, this settings.xml would do that:
{noformat}
<settings>
<mirrors>
<mirror>
<mirrorOf>external:*,!impala.cdp.repo</mirrorOf>
<name>mirror-repo</name>
<url>http://url.to.the.mirror/</url>
<id>mirror-repo</id>
</mirror>
</mirrors>
</settings>{noformat}
It mirrors everything that is not local and not from impala.cdp.repo (which
points to an S3 bucket).
Unfortunately, this rule doesn't work. Everything still tries the mirror. Maven
is trying repositories in the order that they are specified in the pom.xml, and
it sees cdh.rcs.releases.repo before it sees impala.cdp.repo (
[https://github.com/apache/impala/blob/master/java/pom.xml#L150
).|https://github.com/apache/impala/blob/master/java/pom.xml#L150)] It also
sees multiple banned repos (i.e. repos where both snapshots and releases are
disabled). Based on my testing, seeing the cdh.rcs.releases.repo causes it to
try the mirror, because it matches the mirrorOf conditions. It seems like the
banned repositories may also a problem, depending on how smart Maven is.
Reordering the repositories can fix these semantics. If the impala.cdp.repo
comes first (along with the impala.toolchain.kudu.repo), then anything that
matches that would avoid hitting the mirror. Specifically, it seems like the
best ordering would be impala.toolchain.kudu.repo (a local filesystem repo),
impala.cdp.repo (an s3 repo), then the normal server repos, and lastly the
banned repositories.
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