I tried downgrading to Zeal 0.3.1. Normal CPU usage but search doesn't work and I can't even open any docsets, so that isn't useful.

I have reinstalled Zeal with apt and tried building it myself (various versions). Same results unfortunately.

Can you try to profile the app? I doubt there's anything in Zeal code causing the issue...

Sure! Any suggestions for what profiler I should use? What kind of information are you looking for? I've never done it and don't know what profiling means/does.

I'm reading through this stackoverflow question, but it's almost 10 years old so not sure how reliable the suggestions are.

I totally ignored this ticket, sorry.

perf is still the first tool to use, not much really changed in 10 years. Here's an article about some other tools.

I think I have this issue. Zeal keeps hovering around 85% CPU usage constantly, with or without any docsets installed. I'm on Arch Linux, Wayland, and Zeal 0.6.1.

I've attached perf data:

perf.zip

Somehow QNetworkAccessManager creates all the load. @chrisboeg can you check if disabling update check in the settings has any effect?

@trollixx Doesn't seem to make a difference.

@chrisboeg and @trollixx I think I discovered what the issue is. I went to Preferences > Content and at the bottom of the page checked "Disable advertisement on the welcome page". I restarted and now all is well.

Chris do you perhaps also block domains using a hosts file? For me that seems to be causing the problem. When I remove all domains from my hosts file Zeal works fine, regarding of the advertisement settings.

I also run a Pi-Hole which also blocks a bunch of domains. I noticed that after emptying my hosts file, the Pi-Hole blocked cdn.carbonads.com immediately after opening Zeal.

My guess is that when using a hosts file, Zeal keeps on trying to connect to that domain. The weird thing is that with a Pi-Hole the domain is still blocked but Zeal runs normally. There seems to be something about having the domain in the hosts file that causes a problem.

@guushoekman That seems to solve it for me!

I do not block anything using a hosts file, but I do run pi-hole on my home network, although I'm using vpn 100% of the time on the machine running zeal , so I dunno. At least disabling the advertisements made the problem go away for me, as far as I can see, having tested it for a few minutes.

@guushoekman thanks for figuring out the real reason!

Ads have been already removed from the master, so should not be a problem in the next release.

Fixed by 680a1ba, will be released in v0.7.0.

Hi @trollixx, the problem seems to have returned unfortunately. It's the same problem (and I think the same reason) but I think it has to do with individual docsets rather than parts of Zeal itself.

I have ads disabled and when opening Zeal everything is fine. But as soon as I open a docset my CPU starts going insane again. I checked it out and for the Bootstrap 4 docset, for example, I see an attempted connection with srv.carbonads.net as well as www.google-analytics.com.

Conversely, when I open the Django docset it doesn't try to connect to any domain, everything works as it should and CPU usage is normal.

So this seems to be the same underlying problem. Disabling / removing the ads makes Zeal itself work fine, but as long as the docsets still contain code that makes Zeal attempt to make connections to blocked domains then the problem will persist.

@trollixx you can quite easily replicate this issue by adding the above mentioned domains to your hosts file. Let me know if you want to try and/or need help with that.

For now I manually removed the carbonads javascript file and removed all mentions of www.google-analytics.com from the Bootstrap docset. After doing this opening the Bootstrap docset doesn't cause any problems anymore.

This seems like a workaround for now. @chrisboeg I'm tagging you here so if you run into any more problems you can try the same.

Of course removing the problematic domains manually isn't a long-term solution. I'll do it for now since Zeal is an integral part of my workflow (it's really great, thank you so much for your work on it!), but as soon as I update a docset it will mess up again.

Perhaps a proper solution would be to not have Zeal retry domains after they fail. Or even better: that docsets cannot connect to anything at all. I understand Zeal needs a connection in order to download the docsets, but the docsets themselves don't need a connection, right? I have no idea if that's even possible, but I think it would be great because that would not only solve this problem but also remove ads and analytics from all the docsets for people who don't block those domains already.

Zeal used to block all online access, but that was changed a while back (see #474).

I really want to say that it's an issue with docsets (which I have no power over), but maybe it's also a good idea to have an optional offline mode.