How do I contribute code?
Get an account on the Apache Jira.
Find a JIRA that you would like to work on (or file one if you have discovered a new issue!). If no-one is working on it, assign it to yourself only if you intend to work on it shortly. Ramp-up JIRAs are a great place to look for your first patch ideas.
Jira has a whitelist of users that are permitted to modify Jiras. Mail the email@example.com list and request access to assign Jiras to yourself. Please provide your Apache Jira username in the email.
Except for the very smallest items, it’s a very good idea to discuss your intended approach either on the JIRA or on the firstname.lastname@example.org mailing list. You are much more likely to have your patch reviewed and committed if you’ve already got buy-in from the core Impala team before you start.