I just manually combined the separate files and the file loads just fine in qcachegrind. However, they show up in different tabs, so I then removed the header lines from each and the show as one tab/page load.

But I'd rather not have to do that, so hopefully there's a way to fix how xdebug generates the aggregated/appended file!

I think there are two issues here:

1. You can't use xdebug.profiler_append with compressed files. A compressed file can only really exist as a unitary unit, and wouldn't allow for appending. For the same reason you can't just append two .gz files and expect that to work.
2. There is no way to have a single profile from multiple requests. The original "profiler_aggregate" from Xdebug 2 did that, but it never really worked well, and also wasn't working as well as it should be. Reintroducing that could be part of my effort to rewrite the profiler (0002072, just created)

I will re-style this issue to address point 1 above, to disable compression when xdebug.profiler_append is set to 1, and do that as a bug fix for the 3.1.x series.

Does that work?

cheers,
Derick

1. That makes complete sense.
2. How is profiler_append supposed work, if you can't have a single profile from multiple requests? Perhaps you could add a bit more colour in the documentation for the setting?

I look forward to seeing what you come up with for the profiler rewrite!

Thanks so much for such an incredible tool - I only started web development 9 months ago and having xdebug for the past few months has made an incredible difference in my ability to learn and develop. I can't fathom how anyone has ever worked without it.

I've added a warning, with a fallback to uncompressed files, for Xdebug 3.1.x.

I have now also documented this on the website through https://github.com/xdebug/xdebug.org/commit/47a9e25999a6320c108b4d6bb5716f5218e89126 : https://xdebug.org/docs/errors#CFG-W-ZLIB-A