On Aug 12, 2009, at 6:08 AM, Ashish Jain wrote:
Hi,
Recently I have seen difference in the functionality of stop/start
and restart options available against each module. In case of stop/
start I see old classloaders
being discarded and new ones being created. In case of restart same
old classloaders are used.
I am attaching a sample DummyProject here and an explanation of how
it works
It has three classes: TestServlet , TestService and TestBean
1. Request comes to the TestServlet => Console prints “In TestServlet”
2. TestServlet makes a call to the TestService class. TestService
class has a static variable called testBean of type TestBean. This
variable is an initialized during class loading.
4. When the call comes to TestService, if the static variable is
created then the Console prints “In TestBean constructor”. In case
the static variables isn't created then this statement doesn’t get
printed to the console.
5. After which console prints “In TestService class”
Steps to run the application:
1. Deploy this application to WAS community edition
2. Start the application
3. Hit the <WAS url>/<context>/TestServlet
4. Check the console
If static variables are created then all the three statements must
appear as below in the console:
=> In TestServlet
=> In TestBean constructor
=> In TestService class
Restart the application and follow steps 2, 3 and 4. Notice only
first and last statements ('In TestServlet' & ' In TestService
class') appear indicating that static variables aren't created. But
when stop and the start this application, all the 3 statements appear.
I would like to know if this difference is intended or does it
require some fix so that restart behaves in a similar manner as stop/
start?
I'm not sure. My guess is that the differences are unintended, but I'd
have to spend some time to be sure... There may be some consequences
to changing this behavior. David J may have thoughts on this...
A Stop is going to stop a configuration, then unload the configuration
(which will destroy the ClassLoader).
A restart is going to stop a configuration, then start the same
configuration (reusing the same ClassLoader). Thus any static
initialization would have already occurred.
Personally, I think a Restart should be functionally equivalent to
Stop/Start.
--kevan
