Recommendations

Head back to the Blackfire dashboard... and click into the latest profile - the one with our COUNT query improvement - https://bit.ly/sfcast-bf-profile2.

The critical path is now much less clear... there are kind of two critical paths... but neither end in a node with a red background... which would indicate an obvious issue. This might mean that there aren't any more easy performance "wins" on this page... it might be fast enough!

Focus in Improvement, Not Absolute Time

The response time from the profile was 270 milliseconds. If you're not satisfied with that, remember two things. First, we're profiling Symfony in its dev environment. Switching to prod would be faster... we'll do that soon. And second, the time you see in a profile will never be quite as fast as the real thing, because when the probe is activated - the PHP extension that does all the profiling - it slows things down. So don't obsess over any absolute numbers. Instead, focus on finding ways to improve each number.

Switching to Symfony's prod Environment

The function that takes up the most exclusive time is from something called DebugClassLoader. Ah. Our local Symfony app is currently running in its dev environment, which adds a lot of debugging tools, like the web debug toolbar. That stuff also slows things down... which makes profiling less useful: the profiler is cluttered up with function calls that won't really be there in production. That extra noise makes finding the true performance issues harder.

So, let's switch our app to the prod environment while profiling.

Open up .env, find the APP_ENV variable, and change it to prod:

That will make things more realistic... but it also means that after... pretty much any change to our code, we will need to clear & warm the cache. No big deal: at your terminal, run:

php bin/console cache:clear

and then:

php bin/console cache:warmup

Ok, let's profile again! I'll refresh... just to make sure the page is working and... profile! I'll call this one [Recording] Show page in prod mode. Cool! 106 milliseconds is a huge improvement! Click to open the call graph: https://bit.ly/sf-bf-profile3

Now the function list and the call graph look a bit more useful. There's no super problematic, red-background node on the graph... but the function that takes up the most exclusive time - PDOStatement::execute() - at least makes sense: that's executing database queries.

Hello Recommendations

Back on our site, you may have noticed that each time we've profiled, a little exclamation icon showed up. If you clicked that, it would take you to a "Recommendations" section of the profile. The exclamation point was telling us that we're failing one or more Blackfire recommendations.

I dig this feature. Because Blackfire is written for PHP, it has special knowledge of how queries are made, how Composer works, Symfony, Magento and so many other things. The Blackfire team has used that knowledge to add a bunch of things that they call "recommendations". I call them "sanity checks".

For example, Blackfire counted our queries and said:

Hey! FYI - you've got a bunch of queries on this page... maybe you should try to have less than 10.

Yea, our 43 queries is pretty high. Does that mean we should immediately run into our code and fix it? Nah. It's just a good thing to keep on your radar.

There's also a recommendation that Doctrine annotation metadata should be cached in production. Honestly... I'm not sure why that's there - Symfony apps come with a config/packages/prod/doctrine.yaml file that takes care of caching these when you're in the prod environment. When I tried to reproduce this later... it went away. So let's ignore it for now. If it comes back later when we deploy to production, then I will want to look into it further.

Composer Autoloader Recommendation

The last recommendation is awesome:

The Composer autoloader class map should be dumped in production

By the way. if you don't know what something means, the cute question mark can help.

Look back at the function list: the second highest function was something related to Composer's autoload system. Blackfire nailed that this is an issue.

You may already know this, but when you deploy, you're supposed to run a special command - or add a special option - that tells Composer to dump an optimized autoload file. Blackfire is telling us that we forgot to do this locally.

Let's fix this: it will help clean up even more stuff on the profile. At your terminal, run:

composer dump-autoload --optimize

Perfect! Refresh the page... it works... and create another profile - I'll call this: [Recording] Show page after optimized autoloader. Click to view the call graph: https://bit.ly/sf-bf-profile4 and close the old one.

It's not significantly faster, but we've removed at least one heavy-looking function call from our list. That will help us focus on any real problems. Check out the recommendations now. Yea! The Composer one is gone. Later, we'll learn how to add custom assertions - which are basically a way to write your own custom recommendations.

Next, let's look deeper at what's going on with this PDOStatement::execute stuff. Is our page fast enough? Or can we discover some further, hidden optimizations?