Operation Could Not Be Completed: Too Many Open...

I've had this error showing up a lot in the Safari 3.2 and 4.0 beta activity window when loading multiple tabs of pages with many images (usually gallery type pages or blogs with lots of thumbnails). The result is that some images or other elements like style sheets don't load, leading to the blue question mark, or messed up formatting. Unfortunately, the activity window can't be stretched wide enough to see the whole error, but in fact it's "Operation Could Not Be Completed: Too Many Open Files". The error "socket(PF_ROUTE) failed: Too many open files" shows up in the Console as well, at least with Safari 4. I had also experienced similar problems with "Operation Timed Out" errors as well.

I've been pulling my hair out on this one, because it's rather inconsistent, not to mention annoying. You can usually get an individual page to load completely by refreshing it, but that kind of defeats the purpose of loading multiple tabs all at once. It's also less of a problem if more of those pages are already cached, but you never know for sure. Running your connection through a proxy also helps a bit, but not always.

I found a fix, but it's actually not Safari's "fault" per se. The issue lies in the allowable number of open files per user process, which is set by the system's launchd process at boot time. Note that Safari is not entirely innocent, as FireFox doesn't have this problem. It Seems that Safari just tries to load everything all at once, whereas FireFox does a better job of managing its load requests. Anyway if you run the following command in Terminal:

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sudo launchctl limit
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the following list should show up (with perhaps slightly different values)

cpu unlimited unlimited
filesize unlimited unlimited
data 6291456 unlimited
stack 8388608 67104768
core 0 unlimited
rss unlimited unlimited
memlock unlimited unlimited
maxproc 200 532
maxfiles 256 unlimited

The second column is a "soft limit" and the third column is a "hard limit", though to be honest I'm not exactly sure what the difference entails. The image loading problem is caused by hitting the maxfiles limit of just 256 files. The solution is to change maxfiles to 4096/unlimited, and also change maxproc to 1000/2000 since it's pretty low as well. That sounds like a pretty big change, but OS X server is supposed to change them to numbers like this when services like Apache are enabled, and Apple even mentions how to change maxproc at http://support.apple.com/kb/TS1659

To make these changes, run the following two commands in Terminal and restart the computer:

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echo "limit maxproc 1000 2000" | sudo tee -a /etc/launchd.conf
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echo "limit maxfiles 4096 unlimited" | sudo tee -a /etc/launchd.conf
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The commands add the two lines in quotes to the launchd.conf file in /etc/ (if no file exists yet, it creates it). That should clear up the loading issues. I haven't noticed any other problems with these increased numbers, but I'll report back if anything seems to go amiss. Hopefully this will be helpful to someone.