The complexities of handling concurrency successfully in a Node.js context can be overwhelming, especially if you are new to the concept and are sideswiped by bugs that emerge from it.

To prepare you for the troubleshooting tasks that lie in store when wrangling the code for an SQL database, here is a look at why concurrency can cause blocking and what steps you can take to overcome this.

A quick overview of concurrency complications

In order to function efficiently and swiftly, an SQL server takes advantage of concurrency in order to keep multiple processes running simultaneously. Conflicts can occur if two or more processes want to access and alter a specific resource at the same time, although this ‘blocking’ is actually essential to the smooth operation of databases, as explained  on this page.

The simplest way to understand the need for blocking is to think of a web-based banking platform that allows people to store, deposit, and withdraw cash as they see fit. So long as transactions take place one at a time, the balance can be tracked and maintained with ease. However, if two separate withdrawal requests are initiated simultaneously, this could create a doubling effect if there was not a block in place to ensure data integrity and avoid serious errors.

In an SQL environment, processes are assigned locks that allow them exclusive access to a resource until they have completed the necessary action. Locks are assigned to allow processes to take place in a logical sequence, delivering concurrency without the downsides, save the slight speed penalty.

Of course, locks and the blocking they generate can have their own concurrency hurdles to overcome, so a matter that seems straightforward on the surface quickly reveals its more intricate inner workings.

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