We're submitting print jobs using a script to Google Cloud print via cURL and each request seems to take anywhere around 3.5 seconds to complete the request... Which seems like an eternity if your users are used to local printers ;)
This seems way to long for pushing a PDF to their service... As i havent seen any other issues regarding speed / response times I thought of posting it here...
What to do to debug the issue? (if there is anything to do at all?)
Related
I have done something silly and written a script for a website that does an ajax check every 2 seconds. In this case its using wordpress and its admin-ajax.php file every 2 seconds. This essentially burned up all the CPU power of the server, and made every site on the server run really slowly.
After a lot of detective work, i finally found the script and stopped it, so that it doesn't happen on new loads of that website. But looking at my apache log, i can see that it is still running in one browser somewhere.
Is there a way for me to stop that browser from requesting that ajax-call, or perhaps block it from my server? Or will I just have to wait until that browser is being refreshed or closed?
Try to use netstat or something similar through ssh to detect the IP and port of the unknown browser. Also you should try to reboot the server so it may will loose connection.
PS: It's pretty hard to give a clue or answer in the right direction without having any logs or evidence to ensure you answer to this question correctly.
I am using Meteor on Heroku (free tier) with MongoHQ. My app is very simple right now, it loads 3-4 entries from a Collection, but when I deploy it to Heroku, I am seeing ridiculous load times (1-2 minutes). The HTML is rendered immediately. When I deploy to Meteor.com's free server, load times are a lot lower but still about 15 seconds for 4 tiny pieces of data. I'm not seeing this whatsoever when I deploy locally, app pulls data from the DB right away.
It is worth noting that I don't think it's an "idling" issue for Heroku. Even if I already have one browser window with the app just opened, if I use a different browser and try again I still get 1-2 minute load times. Once the data is loaded, however, performance goes back to being great, I can read and write with no problems.
What am I missing? I'm not seeing any errors in the console, mongo shows several queries in the logs and shows that it is responding quickly with 4 documents, but apparently somewhere in the middle there's a traffic jam. Any help with this is greatly appreciated, if I can't get past this Meteor is useless for my needs right now.
UPDATE: I've been watching it closely in Firebug, and it looks like the performance is largely inconsistent. Sometimes a simple refresh will take 1 minute, sometimes it will take 10 seconds. But what I've noticed is that the times when its slow, it GETs the sockjs/info file, then right after that the sockjs POST is aborted (sometimes multiple times). When it runs fast, the POST and subsequent POSTs run smoothly
Slow:
GET http://pocleaderboard.herokuapp.com/sockjs/info 200 OK 22ms
POST http://pocleaderboard.herokuapp.com/sockjs/029/su0d77fb/xhr Aborted
GET http://pocleaderboard.herokuapp.com/sockjs/info 200 OK 27ms
POST http://pocleaderboard.herokuapp.com/sockjs/132/uljqusxd/xhr Aborted
GET http://pocleaderboard.herokuapp.com/sockjs/info 200 OK 28ms
POST http://pocleaderboard.herokuapp.com/sockjs/154/kcbr6a5p/xhr Aborted
Fast(er):
GET http://pocleaderboard.herokuapp.com/sockjs/info 200 OK 1.08s
POST http://pocleaderboard.herokuapp.com/sockjs/755/xiggb555/xhr 200 OK 1.02s
Meteor gets loaded that fast locally, because it doesn't depend on your internet connection and the files can just be read from your harddrive and don't need to be downloaded.
And once the data is loaded it's the same everywhere you host, because the client (you) perform all actions on your cached mongo database and then just wait for the server to say if the action was alright or not.
But for the Heroku loading times, I have no idea, Sorry!
UPDATE:
These are the long-pulls from SockJS that is used by Meteor.
Normally these pulls only get Aborted on a hot code push (when a file is added/changed/removed).
Either you or Heroku seem to write or change something in the directory.
Because then a hot code push may be initiated by Meteor.
Heroku may not support web-sockets, which means you're stuck with the slower polling approach. See this:
https://devcenter.heroku.com/articles/using-socket-io-with-node-js-on-heroku
I am wondering where this comes from : I have a 2 field form for a site that I am building and for some reason, the post request takes up to 13 seconds to complete, according to firebug... The script literally just sends an email in plain text with the user inputs and that's it, nothing complicated.
I am wondering where that delay could come from, any idea ?
Here is a link to a dev version : http://vps-sd.com/sd2012/
I tend not to click links to sites I don't trust, but it could be either
1) Network latency. Are you on a vpn? Where is the dev server hosted? You can use traceroute or something like that to follow the request from the command line.
If both the client and the server are on your dev box this should not be an issue.
2) For really long requests, I think it is more likely something in your dev server is screwed up. It could be the code, or it could be that the dev server is having some issues. Did you log onto the dev server and look at its load? Has some process gone haywire? Has it used all its memory? Did you add some simple benchmarking code to the application server?
You need to diagnose where exactly the slowdown is.
Sometimes, perhaps once every few hundred AJAX requests and/or where AJAX requests are executing in quick succession, I've seen a request hang for up to several minutes before it completes. The weird thing is that the request completes successfully AND neither my machine or the server are really doing anything either (e.g. CPU and other resources are not spiking during the "hang").
I've noticed this issue with various web services too, so it isn't just my own website. It also isn't database related as it has happened on non-database sites. It also only seems to show up in non-localhost environments.
When I personally use AJAX, I am also using jQuery, so this might also be a jQuery issue. I also mostly use Firefox, so I don't know if this is just a Firefox issue or if it is an issue any browser could have. I've run into the issue on multiple computers in multiple locations.
If you have run into this issue before and "fixed" it, I would appreciate the solution you came up with.
Use a HTTP debugger like Firebug or Fiddler to track the AJAX requests to see how much time it takes (possible timeout issue due to server setting?) & what HTTP response status code it returns when it fails. Use the HTTP response status code to troubleshoot the issue.
I am using a modified version of the TaskCloud example to try and read/write my own data.
While testing on a a deployed version, I've noticed that the round-trip response time is slow.
From my Android device, I have a 100ms ping response to appspot.com.
I have changed the AppEngine application to do nothing (The Google Dashboard shows insignificant Average Latency.
The problem is that the time it takes for HttpClient client .execute(post) is about 3 seconds.
(This is the time when an instance is already loaded)
Any suggestions would be greatly appreciated.
EDIT: I've watched the video of Google I/O showing the CloudTasks Android-AppEngine app, and you can see that refreshing the list (a single call to AppEngine) takes about 3 seconds as well. The guy is saying something about performance which I didn't fully get (debuggers are running at both ends?)
The video: http://www.youtube.com/watch?v=M7SxNNC429U&feature=related
Time location: 0:46:45
I'll keep investigating...
Thanks for your help so far.
EDIT 2: Back to this issue...
I've used shark packet sniffer to find out what is happening. Some of the time is spent negotiating a SSL connection for each server call. Using http (and ACSID) is faster than https (and SACSID).
new DefaultHttpClient() and new HttpPost() are used for each server call.
EDIT 3:
Looking at the sniffer logs again, there is an almost 2 seconds delay before the actual POST.
I have also found out that the issue exists with Android 2.2 (all versions) but is resolved with Android 2.3
EDIT 4: It's been resolved. Please see my answer below.
It's difficult to answer your question since no detail about your app is provided. Anyway you can try to use appstats tool provided by Google to analyze the bottleneck.
After using the Shark sniffer, I was able to understand the exact issue and I've found the answer in this question.
I have used Liudvikas Bukys's comment and solved the problem using the suggested line:
post.getParams().setBooleanParameter(CoreProtocolPNames.USE_EXPECT_CONTINUE, false);
Often the first call to your GAE app will take longer than subsequent calls. You should make yourself familiar with loading and warm-up requests and how GAE handles instances of your app: http://code.google.com/intl/de-DE/appengine/docs/adminconsole/instances.html
Some things you could also try:
make your app handle more than one request per instance (make sure your app is threadsafe!) http://code.google.com/intl/de-DE/appengine/docs/java/config/appconfig.html#Using_Concurrent_Requests
enable always on feature in app admin (this will cost you)