Maybe this belongs in the performance forum, or maybe servlets. Please move as needed. The issue is, our home page is suddenly running slower and there have been no changes to our configuration nor have there been any major changes put into production. But our home page has gone from taking about half a second to load, to taking over 10 seconds.
I've attached a screen shot of the Firebug get request. It doesn't tell me much. The tomcat logs don't indicate a problem. Lambda probe shows that memory and thread usage is normal. Very low in fact. CPU utilization seldom goes over 5%.
Can anyone advise me on how to troubleshoot this issue?
"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." -- Ted Nelson
The bottom of firebug request break-up shows some time taking things.
Some png and java script files.
Did someone by any chance change the caching mechanism for JS and images?
"One of the best things you could do is to simplify a larger application into a smaller one by reducing its process and complexity - Fowler"
No changes in caching that I'm aware of and we aren't using a portlet server. I also notice that style.css and Styles.css seem to be a bottleneck. Those are legacy files that contain nothing but a single CSS rule for root:display=block. I don't think they are even used in our application anymore.
I renamed them and the page seems to be back to it's normal load time, but I have no idea why such a small css file would have that dramatic effect.
I see that a whole bunch of them drag and drag and then all slam in at once.
Tomcat doesn't do much magic with files like that, so the bottleneck is probably external. Although you claim that there's more than enough RAM, make sure that it's real RAM and not virtual, as a sudden inrush of paged memory is one possibility. Although that usually shows up as a CPU spike.
It's possible that the real problem isn't even in the server machine itself. Have you checked to see if there are heavy demands running elsewhere on the same network?
An IDE is no substitute for an Intelligent Developer.
I've narrowed this down to an asp page that is being displayed in an iframe. That little css file (style.css) is on the asp server. I haven't worked with iframes so I don't know if the external page is supposed to carry it's included js and css files with it, but when I created that css file on the local tomcat server that started this whole debacle.
I'm going to read up on iframes and do some testing, but it seems I shot myself in the foot with this one. Best intentions and all that...
So you can ignore the page context. What's killing you is fetching those particular items, and they should come back at the same speed whether they're requested from a web page or via a direct URL request of their own.
Based on that attachment you posted, it does show a pattern that most of the things served from within your local tomcat instance is extremely slow as compared to what's served from that 10.x.x.x host. Are you sure you don't have any firewall or anti-virus or any similar stuff on that local instance which might be interfering with these requests?