So I've been running into some speed issues with my site which has been online for a few weeks now. It's an MVC3 site using MySQL on discountasp.net.
I cleaned up the structure of the site and got it working pretty fast on my local machine, around 800-1100ms to load with no caching. The strange thing is when I try and visit the live site I get times of around 15-16 seconds, sometimes freezing up as long as 30 seconds. I switched off the viewstate in web.config and now the local loads in 1.3 seconds (yes, oddly a little longer) and the live site is down to 8-9 seconds most of the time, but that's still pretty poor.
Without making this problem to specific to my case (since there can be a million reasons sites go slow), I am curious if there are any reasons why the load times between the local Visual Studio sever or IIS Express would run so fast while the live site would run so slow. Wouldn't anything code wise or dependency wise effect both equally? I just can't think of a reason that would affect the live site but not the local.
Any thoughts?
Further thoughts: I have the site setup as a sub-folder which I'm using IIS URL Rewriting to map to a subdomain. I've not heard of this causing issues before, but could this be a problem?
Further Further Updates: So I uploaded a simple page that does nothing but query all the records in the largest table I have with no caching. On my local machine it's averages around 110ms (which still seems slow...), and on the live site it's usually over double the time. If I'm hitting the database several times to load the page, it makes sense that this would heavily affect the page load time. I'm still not sure if the issue is with LINQ or MySQL or MVC in general (maybe even discountasp.net).
I had a similar problem once and the culprit was the initialization of the user session. Turns out a lot of objects were being read/write to the session state on each request, but for some reason this wasn't affecting my local machine (I probably had InProc mode enabled locally).
So try adding an attribute to some of your controllers and see if that speeds things up:
[SessionState(SessionStateBehaviour.Disabled)]
public class MyController : Controller
{
On another note, I ran some tests, and surprisingly, it was faster to read some of those objects from the DB on each request than to read them once, then put them in the session state. That kinda makes sense, since session state mode in production was SqlServer, and serialization/deserialization was apparently slower than just assigning values to properties from a DataReader. Plus, changing that had the nice side-effect of avoiding deserialization errors when deploying a new version of the assembly...
By the way, even 992ms is too much, IMHO. Can you use output caching to shave that off a bit?
So as I mentioned above, I had caching turned off for development, but only on my local machine. What I didn't realise was there was a problem WITH the caching which was turned on for the LIVE server, which I never turned off because I thought it was helping fix the slow speeds! It all makes sense now :)
Fixing my cache issue (IQueryable<> at the top of a dataset that was supposed to cache the entire table.. >_>) my speeds have increased 10 fold.
Thanks to everyone who assisted!
Related
I've heard often that deploying a traditional monolithic Rails app (i.e. no internal Web API, no message queue, no Redis/memcached server) to multiple servers can produce a bunch of bugs that are very hard to debug but I'm having a hard time coming up with some concrete examples despite a few hours of googling
Some obvious issues that I can think of are:
Observers - likely will not work properly as the observation is only propagated on one server and not all of them (assuming there is no Message Queue)
Sessions - would probably need to store these in the database which would need it's own host
Caches - any sweepers would have issues propagating invalidations between servers.
Anyone else care to contribute? I'd really appreciate any articles others may have come across or just general wisdom :)
Observers are just code callbacks.
They run on each process, on each server.
Sessions have defaulted to the cookie store for the last few years.
So multiple servers are no problem.
If you don't have enough space in your cookie then I suggest you may be doing something wrong.
Cache invalidation is indeed a problem.
But it always is.
One solution is to break your cache out into a standalone service.
Sites like Facebook have giant farms of memcache
I think scaling and clustering is always a hard problem.
But this seems to be an old argument against rails.
If anything the last few years have seen rails shine in this respect.
With ec2, nosql, and server automation becoming quite a norm in the community.
We have a MVC 3 application which has been deployed onto a newly built Windows 2008 R2 Web Edition server which is performing badly.
This application has been through development, quality assurance and user acceptance testing cycles on the same operating system (different boxes) with no performance issues.
The only difference we can see with the server is that it sits in the DMZ and as such has two network adapters configured, one for the internet, and one to punch through the firewall.
We have put all sorts of logging into the application and confirmed that up until the 'return ActionResult' everything is working correctly (ie ~500ms). It then takes 15 seconds to render the page.
We have tried turning on debug=false in the config file, i'm not sure what else to look for here, it seems like an environment issue.
Any suggestions please ? I am about to investigate if the thread pool size could be causing problems.
Also, if it helps the page is using multiple partial views, i have read others having problems with them.
Thanks,
Matt
Since the application performs ok in other environments I would suggest you investigate following:
Database - are you running against different database? How long the queries execute? If you have non-optimized database with million records on production, and only few records in test you want find performance problems soon enough.
Network - what is the latency between web box and database? If you loose 100ms for each database query just because of network than if your page triggers 50 queries you've lost 5secs. I've seen poorly configured routers / load balancers that were doing just that.
Try profiling each component of your system (db, network, web box) in order to find out where you're wasting all that time. Try http://code.google.com/p/mvc-mini-profiler/.
PS. You MUST have debug=false in your prod env.
Hi
I've been working on a medium sized MVC project. It works fine on the localhost at a good speed rate. In each page, there's a lot of server-side data retrieved, I use a lot of jquery to minimize the traffic to the server, but even then, the webpage loads very slowly. There are many events on which I retrieve json results, to get a specific number from the database and make calculations, this data takes a long time to be retrieved on the webpage, although on the localhost it is immediately shown. Also, when I submit pages, it takes awfully a lot of time to submit. I've published my project to GoDaddy's server and also my database is there. What could be the problem that is making the project that slow? How can I minimize it? And why is it only when the website is online and not on the localhost too?
As such, issue can be anywhere and only certain way to know is instrumenting the code. I will suggest that you add simple logging traces with date-time stamp in your server code (note that logging should be configurable, any logging framework (including System.Diagnostic.Trace) should support it) and check where the time is spent. For example, database trips can be expensive etc. If you don't find the culprit on server side code i.e. sever is serving the request in reasonable time then you have to look at the performance over network. Tools such as Fiddler (or Firefox) should help you here - sometimes issuing too many requests from browser is also problematic because browser may make only n concurrent requests or even server may have been configured to accept only n requests from particular client - this could result in serialization of request increasing total response time. These scenarios are difficult to catch on localhost because network latency is almost zero there. You may also use tool such as YSlow for related performance improvement suggestions. But please do your investigation first, find the bottlenecks and then ask for solutions to specific problems.
Run it in chrome. Turn on the developer tools. Expand the Console. watch for errors. Also from there you can monitor those network calls to see which is slow.
if MVC uses entity framework (based on LINQ), it will sure be slow
because LINQ is slow compared to the old ADO.NET
I have a website that is hanging every 5 or 10 requests. When it works, it works fast, but if you leave the browser sit for a couple minutes and then click a link, it just hangs without responding. The user has to push refresh a few times in the browser and then it runs fast again.
I'm running .NET 3.5, ASP.NET MVC 1.0 on IIS 7.0 (Windows Server 2008). The web app connects to a SQLServer 2005 DB that is running locally on the same instance. The DB has about 300 Megs of RAM and the rest is free for web requests I presume.
It's hosted on GoGrid's cloud servers, and this instance has 1GB of RAM and 1 Core. I realize that's not much, but currently I'm the only one using the site, and I still receive these hangs.
I know it's a difficult thing to troubleshoot, but I was hoping that someone could point me in the right direction as to possible IIS configuration problems, or what the "rough" average hardware requirements would be using these technologies per 1000 users, etc. Maybe for a webserver the minimum I should have is 2 cores so that if it's busy you still get a response. Or maybe the slashdot people are right and I'm an idiot for using Windows period, lol. In my experience though, it's usually MY algorithm/configuration error and not the underlying technology's fault.
Any insights are appreciated.
What diagnistics are available to you? Can you tell what happens when the user first hits the button? Does your application see that request, and then take ages to process it, or is there a delay and then your app gets going and works as quickly as ever? Or does that first request just get lost completely?
My guess is that there's some kind of paging going on, I beleive that Windows tends to have a habit of putting non-recently used apps out of the way and then paging them back in. Is that happening to your app, or the DB, or both?
As an experiment - what happens if you have a sneekly little "howAreYou" page in your app. Does the tiniest possible amount of work, such as getting a use count from the db and displaying it. Have a little monitor client hit that page every minute or so. Measure Performance over time. Spikes? Consistency? Does the very presence of activity maintain your applicaition's presence and prevent paging?
Another idea: do you rely on any caching? Do you have any kind of aging on that cache?
Your application pool may be shutting down because of inactivity. There is an Idle Time-out setting per pool, in minutes (it's under the pool's Advanced Settings - Process Model). It will take some time for the application to start again once it shuts down.
Of course, it might just be the virtualization like others suggested, but this is worth a shot.
Is the site getting significant traffic? If so I'd look for poorly-optimized queries or queries that are being looped.
Your configuration sounds fine assuming your overall traffic is relatively low.
To many data base connections without being release?
Connecting some service/component that is causing timeout?
Bad resource release?
Network traffic?
Looping queries or in code logic?
I have a simple Rails app deployed on a 500 MB Slicehost VPN. I'm the only one who uses the app. When I run it on my laptop, it's fast enough. But the deployed version is insanely slow. It take 6 to 10 seconds to load the login screen.
I would like to find out why it's so slow. Is it my code? (Don't think so because it's much faster locally, but maybe.) Is it Slicehost's server being overloaded? Is it the Internet?
Can someone suggest a technique or set of steps I can take to help narrow down the cause of this problem?
Update:
Sorry forgot to mention. I'm running it under CentOS 5 using Phusion Passenger (AKA mod_rails or mod_rack).
If it is just slow on the first time you load it is probably because of passenger killing the process due to inactivity. I don't remember all the details but I do recall reading people who used cron jobs to keep at least one process alive to avoid this lag that can occur with passenger needed to reload the environment.
Edit: more details here
Specifically - pool idle time defaults to 2 minutes which means after two minutes of idling passenger would have to reload the environment to serve the next request.
First, find out if there's a particularly slow response from the server. Use Firefox and the Firebug plugin to see how long each component (including JavaScript and graphics) takes to download. Assuming the main page itself is what is taking all the time, you can start profiling the application. You'll need to find a good profiler, and as I don't actually work in Ruby on Rails, I can't suggest any: google "profile ruby on rails" for some options.
As YenTheFirst points out, the server software and config you're using may contribute to a slowdown, but A) slicehost doesn't choose that, you do, as Slicehost just provides very raw server "slices" that you can treat as dedicated machines. B) you're unlikely to see a script that runs instantly suddenly take 6 seconds just because it's running as CGI. Something else must be going on. Check how much RAM you're using: have you gone into swap? Is the login slow only the first time it's hit indicating some startup issue, or is it always that slow? Is static content served slow? That'd tend to mean some network issue (either on the Slicehost side, or your local network) is slowing things down, assuming you're not in swap.
When you say "fast enough" you're being vague: does the laptop version take 1 second to the Slicehost 6? That wouldn't be entirely surprising, if the laptop is decent: after all, the reason slices are cheap is because they're a fraction of a full server. You're using probably 1/32 of an 8 core machine at Slicehost, as opposed to both cores of a modern laptop. The Slicehost cores are quick, but your laptop could be a screamer compared to 1/4 of core. :)
Try to pint point where the slowness lies
1/ application is slow, or infrastructure (network + web server)
put a static file on your web server, and access it through your browser
2/ If it is fast, it is probable a problem with application + server configuration.
database access is slow
try a page with a simpel loop: is it slow?
3/ If it slow, it is probably your infrastructure. You can check:
bad network connection: do a packet capture (with Wireshark for example) and look for retransmissions, duplicate packets, etc.
DNS resolution is slow?
server is misconfigured?
etc.
What is Slicehost using to serve it?
Fast options are things like: Mongrel, or apache's mod_rails (also called passenger phusion or
something like that)
These are dedicated servers (or plugins to servers) which run an instance of your rails app.
If your host isn't using that, then it's probably defaulting to CGI. Rails comes with a simple CGI script that will serve the page, but it reloads the app for every page.
(edit: I suspect that this is the most likely case, that your app is running off of the CGI in /webapp_directory/public/dispatch.cgi, which would explain the slowness. This tends to be a default deployment on many hosts, since it doesn't require extra configuration on their part, but it doesn't give good performance)
If your host supports "Fast CGI", rails supports that too. Fast CGI will open a CGI session, and keep it open for multiple pages, so you get much better performance, but it's not nearly as good as Mongrel or mod_rails.
Secondly, is it in 'production' or 'development' mode? The easy way to tell is to go to a page in your app that gives an error. If it shows you a stack trace, it's in development mode, which is slower than production mode. Mongrel and mod_rails have startup options to determine whether to run the app in production or development mode.
Finally, if your database is slow for whatever reason, that will be a big bottleneck as well. If you do have a good deployment (Mongrel/mod_rails/etc.) in production mode, try looking into that.
Do you have a lot of data in your DB? I would double check that you have indexed all the appropriate columns- because this can make a huge difference. On your local dev system, you probably have a lot more memory than on your 500 mb slice, which would result in the DB running a lot slower if you have big, un indexed tables. You can also run the slow queries logger in MySql to pinpoint columns without indexes.
Other than that, yes- passenger will need to spool up a process for you if you have not been using the site recently. If this is the case, you should see a significant speed increase on second, and especially third and later page loads.
You might want to run a local virtual machine with 500 MB. Are you doing a lot of client-server interaction? Delays over the WAN are significant
You might want to check out RPM (there's a free "lite" version too) and/or New Relic's Tune Up.
Your CPU time is guaranteed by Slicehost using the Xen virtualization system, so it's not that. Don't have the other answers for you, sorry! Might try 'top' on a console while you're trying to access the page.
If you are using FireFox and doing localhost testing (or maybe even on LAN) you may want to try editing the network.dns.disableIPv6 setting.
Type about:config in the address bar and filter for network.dns.disableIPv6 and double-click to set to true.
This bug has been reported mainly from Vista OS's, but some others as well.
You could try running 'top' when you SSH in to see which process is heavy. If you also have problems logging you, perhaps you may try getting Statistics in the Slicehost manager.
If you discover it is MySQL's fault, consider decreasing the number of servers it can spawn.
512 seems decent for Rails application, you might have to check if you misconfigured too.