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Community code review is Spark's fundamental quality assurance process. When reviewing a patch, your goal should be to help streamline the committing process by giving committers confidence this patch has been verified by an additional party. It's encouraged to (politely) submit technical feedback to the author to identify areas for improvement or potential bugs.
If you feel a patch is ready for inclusion in Spark, indicate this to committers with a comment such as: "I think this patch looks good". Spark uses the LGTM convention for indicating the strongest level of technical sign-off on a patch: simply comment with the word "LGTM". An LGTM is a strong statement with specific semantics. It should be interpreted as the following: "I've looked at this thoroughly and take as much ownership as if I wrote the patch myself". If you comment LGTM you will be expected to help with bugs or follow-up issues on the patch. Judicious Consistent, judicious use of LGTM's is a great way to gain credibility as a reviewer with the broader community.
It's also welcome for reviewers to argue against the inclusion of a feature or patch. Simply indicate this in the comments.
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