Step by Step Trouble Shooting

Performance SOP

Identify the Bottleneck

Usually the bottleneck can be found in one of these areas:

• network
• server
• client

To breakdown a slow performing web application is a good idea to start, where the bad performance is perceived... in the browser. Most modern browsers provide very sophisticated tools to start the search for the bottleneck and draw some conclusions, and exclude other possible causes easily.

Dev tools (Network)

Chrome [F12]

Firefox [F12] / Firebug

IE>9 [F12]

fiddler2 TODO

After a few minutes the biggest problem area should become clear, following the questions below:

Is there is one or more long running requests?

NO --> client side

YES -->

Is it a static resource?

YES (js, css, images ...) --> check debug mode zk config (disabled by default) http://books.zkoss.org/wiki/ZK_Configuration_Reference/zk.xml/The_client-config_Element/The_debug-js_Element --> check caching config (enabled by default) http://books.zkoss.org/wiki/ZK_Configuration_Reference/zk.xml/The_Library_Properties/org.zkoss.web.classWebResource.cache http://books.zkoss.org/wiki/ZK_Configuration_Reference/zk.xml/The_Library_Properties/org.zkoss.zk.WPD.cache http://books.zkoss.org/wiki/ZK_Configuration_Reference/zk.xml/The_Library_Properties/org.zkoss.zk.WCS.cache

??? maybe more tweaks ???

--> NONE of these --> network

NO dynamic request

- *.zul = full page request (can be followed by ajax requests)
- zkau/* = ajax request

Which stage of the request is slow ?

network (based on Chrome Developer tools -> Network -> Timing)

1. connecting (Proxy, DNS Lookup, Blocking, SSL)
 - slow proxy/DNS/Blocking/SSL/ (client -> proxy -> webserver/firewall -> appserver) = network or server side problem

Is this a network problem (everything between browser and ZK Application)? -> test ping / trace route to different servers -> test dns lookup timing YES --> ask your administrator to fix it ;)

NO = appserver responding slowly --> server side problem

2. sending

Is the request unreasonably big? YES -> client side problem NO

  	Is the bandwidth low? 

- try upload the same amount of data to the server, e.g. ftp/scp, to check upload speed YES --> ask your administrator to fix it ;) NO --> appserver reading slowly --> server side problem

3. waiting
  --> server side problem

4. receiving

Is the response unreasonably big? --> check ROD (Render on Demand) settings YES -> server side problem NO

  	Is the bandwidth low? 

- try download the same amount of data from the server, e.g. ftp/scp, to check download speed YES --> ask your administrator to fix it ;) NO --> appserver writing slowly --> server side problem