Step by Step Trouble Shooting

Performance SOP

Identify the Bottleneck

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

• client
• network
• server

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] or Firebug

IE9+ -> [F12]

IE8 -> fiddler2

Investigating the network traffic following the questions below the biggest problem area(s) should become apparent after a few minutes:

1. Are there one or more long running requests?

NO → #Client Side Issue

YES

↓

2. Is it a static resource?

YES (js, css, images...) → check #ZK Server Configuration → STILL SLOW → #Network Issue

NO (dynamic request into ZK application)

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

↓

3. Which PHASE of the request is slowest ? (examples based on Chrome developer tools)

CONNECTING (or one of Proxy, DNS Lookup, Blocking, SSL)

3.a) Is this a network problem (everything between browser and ZK Application)?

• test ping / trace route to different servers
• test dns lookup timing

YES → #Network Issue

NO → #Server Side Issue (application server responding slowly, or even times out)

SENDING

3.b) Is the request unreasonably big?

YES → #Client Side Issue

NO

↓

3.c)Is the bandwidth low?

• e.g. try upload the same amount of data to the server via ftp/scp to check possible upload speed

YES → #Network Issue

NO → #Server Side Issue (application server receiving slowly)

WAITING → #Server Side Issue (application server taking long time to prepare response)

4. receiving

Is the response unreasonably big? --> check ROD (Render on Demand) settings YES -> #Server Side Issue 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 Issue

Network Issue

not part of this SOP, ask your network administrator

Server Side Issue

ZK Server Configuration

• check debug mode → zk config should not be enabled (disabled by default)
  • http://books.zkoss.org/wiki/ZK_Configuration_Reference/zk.xml/The_client-config_Element/The_debug-js_Element

• check caching config → should not be disabled (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

• TODO ??? maybe more tweaks ???