>From: Michael Bergknoff <[EMAIL PROTECTED]>
>Does the container maintain session state across
>a destroy/init sequence? If so is it up to each
>servlet to serialize or delete any objects stored
>in the session? For debugging, is it possible to
>control when the destroy method is called?
>
>Thanks,
>Mike
>[...]
Hi :-) I am not sure:
- IMHO, I think HttpSession doesn't has much relation
with one special MyServlet, session is "of"
webapps/container(not this webapp or that...), i.e.,
session is cross-webapp, so session is loaded by
another classloader which is different from the webapp
classloader which loads MyServlet. so even if the old
webapp classloader is destroyed/GCed, the session object
and its Class object and its classloader are still there.
- it seems that the following "events" are Not
always "together":
% MyServlet is loaded by webapp classloader
% and 1/n instance(s) is/are made
% init method is called by container
% destroy method is called by container
% 1/n instance(s) is/are destroyed/GCed
% another 1/n instance(s) is/are made again
% old webapp classloader is destroyed/GCed
% new webapp classloader is made again
% ...
i.e. I guess it is possible that:
destroy method is called, but the old instance of
MyServlet is still there(and/or the old webapp classloader
is still there).
- so if we are sure that all the objects which are put into
session by us are Not loaded by webapp classloader, I think
we can be sure that we don't need to consider the init/destroy
issue, if they are loaded by webapp classloader, And at the same
time when init/destroy is being called, the old webapp classloader
is destroyed/GCed and a new one is made, perhaps we will meet some
problem, for xample, ClassCastException or other...
- perhaps it is better to make all the following serialized:
% the objects which are put into HttpSession
% the objects which are put into ServletContext
Bo
May.06, 2001
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