The job scheduler is part of the operating system that takes care of the alternation of the various tasks in the background, and that in practice decide who should do what, and especially when. It is a process that is constantly being optimized in the various iterations of Android, and that also in the future N release will have some important news.
One aspect in particular has been the subject of attention: that is what happens after you have taken a picture or when you enable the Wi-Fi after a period in which it was switched off. Many apps in your smartphone can indeed perform actions as a result of what the others do, such as automatic backups of photos or other, and if they were so many wanting to perform different tasks, could easily create a bottleneck at a certain occurrence conditions, just as the power of Wi-Fi, which allows the backup.
With Android N, instead of having the app that constantly seek to charge each image or data, the upload will take place in blocks, and especially when the job scheduler will communicate to the various apps that came their turn, thus preventing all want in practice jump the queue instead of creating a traffic jam. What does this mean? Less slowdowns at certain times and more consistent performance during the use of your device.
Until Lollipop, if a developer wanted to run a background task (for example, to request data from a server or simply run an intensive work for the processor), the application had to listen to certain events or schedule recurring alarms for checks. In addition, the app should be determining whether conditions (eg, internet access) were ideal or should postpone some work.
With that situation was born the idea of job scheduler for Android Lollipop. The mission was to act as a dispatcher application, responsible for launching those who are in the right conditions, so no longer need to monitor a manually whether or not we have the necessary conditions. Undoubtedly, it was a new breakthrough and a great improvement that now is even bigger.