Skip to main content

Debugging slow VSCode TS project with tsc generateTrace

VS code feels slow. All of a sudden, saving took forever in a TS project. The first suspect was a recently added WallabyJS test runner extension. So I disabled all plugins but still, saving took several seconds.

My head then turned towards TS. Arrogantly I blamed some dependency but I had not a clue which one. Github TS wiki has some tips and tricks on what to do, including instructions to run a profiler. Turns out, a new profiling tool was introduced not too long ago in TS 4.1. 

The output looks like this.

Compiling the slowest source file takes more than 7 seconds!

There is one massively slow checkSourceFile call which, as the name says, compiles a single file. To my embarrassment, it was in my code 😱

The profiling output is rather hard to decipher. The UI shows which TS internal functions are called and references a separate JSON file containing the type names. In my case, the slow function(s) included some weird single character type names, so it was not much help.

The arguments are references to types.json file

I reverted to bisect debugging. I randomly removed code until all was back to normal. Turns out, the bug was in react-hook-form typing. I had an "extra" type in the form controllers reducing the performance massively. I did not dig too profoundly into why this happens, but I should definitely open an issue. 

After the fix, the source file was gone from the trace tool visualization and vscode is back to normal speed.

Still, a bit slow component to compile, but much better


Labels:

Comments

Post a Comment

Popular posts from this blog

I'm not a passionate developer

A family friend of mine is an airlane pilot. A dream job for most, right? As a child, I certainly thought so. Now that I can have grown-up talks with him, I have discovered a more accurate description of his profession. He says that the truth about the job is that it is boring. To me, that is not that surprising. Airplanes are cool and all, but when you are in the middle of the Atlantic sitting next to the colleague you have been talking to past five years, how stimulating can that be? When he says the job is boring, it is not a bad kind of boring. It is a very specific boring. The "boring" you would want as a passenger. Uneventful.  Yet, he loves his job. According to him, an experienced pilot is most pleased when each and every tiny thing in the flight plan - goes according to plan. Passengers in the cabin of an expert pilot sit in the comfort of not even noticing who is flying. As someone employed in a field where being boring is not exactly in high demand, this sounds pro...
Post a Comment
Read more

Bird is causing high CPU on my macOS

There is no lack of people complaining about MacOS Tahoe, mostly about rounded corners and inconsistent design decisions. I have not paid that much attentention to that, but there is one mac bug i have paid attention to. It hasn't been a visual or ux but rather few system processes pegging the CPU. trustd , alongside with ecosystemd and ecosystemanalyticsd all reported high CPU usage. I can't exactly recall when this started, it might have predated my Tahoe upgrade but anyway, the trio of processes all had high CPU usage. Sure, it may have been the virtual efficiency cores and whether it affeced battery life or slowed down other processes i don't know to be hon...
Post a Comment
Read more

Ousterhout's law

Back in the day, everyone was using Winamp. It is a music player with the user interface of a mixing console. The bloody thing had an equalizer on the front page! As an amateur music producer, I know that EQ is a powerful tool but making changes that sound good is difficult, to say the least. Mixing engineers spend considerable effort with the artist to balance the frequency ranges to arrive at the desired musical outcome. I bet the 15-year-old me butchered a lot of songs with the thing. Now we are using Spotify, a player with basically a search bar and a play button. I ran into something called Ousterhout's Law on the  Operating Systems: Three Easy Pieces book . Here is a quote from the book TIP: AVOID VOO-DOO CONSTANTS (OUSTERHOUT’S LAW) Avoiding voo-doo constants is a good idea whenever possible. Unfortunately, as in the example above, it is often difficult. One could try to make the system learn a good value, but that too is not straightforward. The frequent result: a configura...
Post a Comment
Read more