I was wondering what modules of the Hangfire.Core or Hangfire.SqlServer is in charge of dequeing an enqueued job and processing it? And can we custom these methods?
@Jiarui_Hou, Hangfire.Core contains all the types and methods Hangfire brings, with abstracted job storage. Hangfire.SqlServer contain storage implementation related to SQL Server. But I don’t understand, what do you want to achieve. Can you detail your questions?
What I mean is that I’d like to have the capabilities of customizing Hangfire library methods if possible. For example, alter the built-in timer duration, so it dequeues jobs more or less frequently.
Hangfire is customizable a lot, but this concept is not well documented yet 
If you like to read the source code, you’ll receive the following ways to customize it:
- Add code before and after creating a background job (through client filters).
- Add code actions before and after performing a background job (through server filters). Please see CaptureCultureAttribute for example.
- Modify the state change pipeline, including introducing the new states (through state filters and custom states). See AutomaticRetryAttribute and QueueAttribute for examples.
- You can use extensible job storage to persist your own data.
- You can add new pages to the Hangfire dashboard (in 1.4 it will be possible to alter the dashboard menu either).
- You can add support for your own storage.
- Maybe other things I’ve missed
As you can see, there are a lot of work for the documentation 
Would you mind elaborating little on introducing new states. My jobs can take a long time to cancel and I would like a Cancelling state…