Future Kyle:
Apache 2.4 w/ mod_dav_svn on Debian (Buster) for svn distribution may see frequent timeouts when checking out or updating large repositories. Your client will fail with this error:
svn: E120106: ra_serf: The server sent a truncated HTTP response body
You will see the following your vhost error.log:
[cgid:error] [pid x:tid y] AH01239: cgid daemon process died, restarting
You will scratch your head and google around for a few hours, hitting the following red herrings along the way:
- mod_deflate will alleviate it slightly; your update will make it further before failing
- Turning off KeepAlive or adjusting timeouts will also seem to alleviate it slightly, but it's likely not clear to you how much it helped
Your solution appears to be, at this point in time, to set SVNAllowBulkUpdates prefer in your svn vhost. This will force clients to use bulk-updates instead skelta, which seems to be the crux of the issue. You're currently 10 minutes in to the checkout you were attempting without any problems.