On Wed, Aug 28, 2019 at 4:51 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > francis picabia <fpica...@gmail.com> writes: > > The server was running Moodle. The slow load time was noticed when > loading > > a quiz containing > > multiple images. All Apache log results showed a 6 seconds or a multiple > > of 6 for how long > > it took to retrieve each image. > > > Interestingly, if I did a wget, on the server, to the image link (which > was > > processed through a pluginfile.php URL) > > even the HTML page returned of "please login first" took consistently 6 > > seconds. Never 2, 3, 4, 5 or 7, 8, 9... > > So whatever was wrong, there was a 6 second penalty for this. > > Hmm ... some weird DNS behavior, perhaps? That is one way to explain > a pattern like this. How long does it take to "dig" or "nslookup" > your server name? > > regards, tom lane >
Nope, it isn't DNS related. The dev server uses same DNS service and was very fast to do the same actions. I also run the DNS server and would be aware of any complaints about the performance. I thought firewall for awhile but there was nothing there related to it. It all cleared up minutes after the *vacuum -a -v -z *was run, and was reported slow several days before this. I myself saw it consistently slow for the quiz for the 2.5 days I fought the problem. We're certain the vacuum made the difference in performance. If there is no way to log the "user time", I guess we'd need to log something like the connection and disconnection to get another idea on the time elapsing.
