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Sapienz and SapFix are automated tools that Facebook now uses to find and fix problems across all of the company’s apps Facebook’s Getafix tool serves up templates for how to fix common coding errors to its SapFix system, which then recommends solutions to developers. A null pointer exception is like having the address to a house that was never built. It means a programmer has referred to an object that doesn’t actually exist because it was never described in the code.

Switch provisioning at Dropbox is handled by a Pirlo component called the TOR Starter. The TOR Starter is responsible for validating and configuring switches in our datacenter server racks, PoP server racks, and at the different layers of our datacenter fabric that connect racks in the same facility together. Writing the TOR Starter on top of the ClusterOps queue provides us with a basic manager-worker queuing service. We also have the ability to customize the queue to fit our needs in switch provisioning.