Profiler#

PHP code profiling allows you to inspect how much time and how many calls were made to every single function in the code.

Quickly Setup PHP for Profiling#

Ensure, you have PHP installed.
Ensure Xdebug PHP extension is installed as well.
Make sure PHP zlib extension is enabled (recommended).

Check your php.ini setting:

xdebug.output_dir="<an output directory>"

Use the following launch.json setting:

{
    "name": "Launch Built-in server & Profile",
    "type": "php",
    "request": "launch",
    "runtimeArgs": [
        "-S", "localhost:8888", "-t", "."
    ],
    "noDebug": true, // <-- disable debugging
    "profile": true, // <-- enable profiling
    "openProfile": false, // <-- whether to open profiling results after session ends
}

After launching the built-in server using the launch configuration above, do a request to the web application. A new profile file (cachegrind.out.*.gz) will be created.

Opening Profiling Result#

Open the file containing your profiling data. By default, it is in form of cachegrind.out.*.gz.

Using Command Palette

Bring the Command Palette, and run Open Profile File (Xdebug Profiling Output).
Choose the file, and confirm.

Drag & Drop 'cachegrind.out.*.gz' File

Alternatively, if your profile file name is in form of cachegrind.out.*.gz, you can open the file right in the Visual Studio Code editor - using File/Open File menu.

Be aware, large files may take some time to open.

Inspecting Call Times#

The following view lists all the functions with the number of calls (Calls), time spent by the function body (Self Time), and time including nested calls (Time).

Inspecting Callers/Callees#

The Function Details view is focused on a single function; and displays all the calling functions and all the called functions, including the time information.

Highlighting Hot Paths#

The loaded profiling result file is analyzed, and hot paths are highlighted directly in the source code. Highlighting can be turned off in the profiling result view.