The importance of profiling

Now that we know what profiling means, it is also important to understand how important and relevant it is to actually do it during the development cycle of our applications.

Profiling is not something everyone is used to do, especially with non-critical software (unlike peace maker embedded software or any other type of execution-critical example). Profiling takes time and is normally useful only after we've detected that something is wrong with our program. However, it could still be performed before that even happens to catch possible unseen bugs, which would, in turn, help chip away the time spent debugging the application at a later stage.

As hardware keeps advancing, getting faster and cheaper, it is increasingly hard to understand why we, as developers, should spend resources (mainly time) on profiling our creations. After all, we have practices such as test-driven development, code review, pair programming and others that assure us our code is solid and that it'll work as we want it. Right?

However, what we sometimes fail to realize is that the higher level our languages become (we've gone from assembler to JavaScript in just a few years), the less we think about CPU cycles, memory allocation, CPU registries, and so on. New generations of programmers learn their craft using higher level languages because they're easier to understand and provide more power out of the box. However, they also abstract the hardware and our interaction with it. As this tendency keeps growing, the chances that new developers will even consider profiling their software as another step on its development grows weaker by the second.

Let's look at the following scenario:

As we know, profiling measures the resources our program uses. As I've stated earlier, they keep getting cheaper and cheaper. So, the cost of getting our software out and the cost of making it available to a higher number of users is also getting cheaper.

These days, it is increasingly easy to create and publish an application that will be reached by thousands of people. If they like it and spread the word through social media, that number can blow up exponentially. Once that happens, something that is very common is that the software will crash, or it'll become impossibly slow and the users will just go away.

A possible explanation for the preceding scenario is, of course, a badly thought and non-scalable architecture. After all, one single server with a limited amount of RAM and processing power will get you so far until it becomes your bottleneck. However, another possible explanation, one that proves to be true many times, is that we failed to stress test our application. We didn't think about resource consumption; we just made sure our tests passed, and we were happy with that. In other words, we failed to go that extra mile, and as a result, our project crashed and burned.

Profiling can help avoid that crash and burn outcome, since it provides a fairly accurate view of what our program is doing, no matter the load. So, if we profile it with a very light load, and the result is that we're spending 80 percent of our time doing some kind of I/O operation, it might raise a flag for us. Even if, during our test, the application performed correctly, it might not do so under heavy stress. Think of a memory leak-type scenario. In those cases, small tests might not generate a big enough problem for us to detect it. However, a production deployment under heavy stress will. Profiling can provide enough evidence for us to detect this problem before it even turns into one.