Clarify the limitations on using the request and response from an application thread about servlet

[glassfishrobot]

• Issue Imported From: https://github.com/javaee/servlet-spec/issues/41
• Original Issue Raised By:@glassfishrobot
• Original Issue Assigned To: @glassfishrobot

[glassfishrobot]

@glassfishrobot Commented
Reported by rstoyanchev

[glassfishrobot]

@glassfishrobot Commented
gregwilkins said:
Note that just because tomcat and glassfish return non null values from these methods does not mean that they are "working".

In an environment where a request can be dispatched to one context, suspended by another context and then handled by yet another context, it is entirely undefined what values should be returned to an asynchronous thread calling any method dependant on the current context.

Jetty does return values to these methods depending on what context they are currently dispatched to, so if an async thread calls these methods before the original dispatch has returned, they will give non null value. If the request is not currently dispatched to a context, then these methods return their initial settings (contextPath==null, servletPath==null, pathInfo==requestedURI).

I think that only the request attributes should be asynchronously accessible (and my preference is to have an accessor method for these on AsyncContext).

[glassfishrobot]

@glassfishrobot Commented
rstoyanchev said:
Greg, I am certainly not in a position to say if the values returned from the request in Glassfish and Tomcat after a call to startAsync work in general. On the contrary, I stated it's not clear if the request can be used reliably in that scenario and asked for clarification.

From the point of view of a Servlet API user, there is an AsyncContext and it provides access to the request and response. With no further indication in the spec and the Javadoc, it's not obvious that as many attributes and operations are to be avoided altogether.

I think that only the request attributes should be asynchronously accessible (and my preference is to have an accessor method for these on AsyncContext).

Do I understand correctly all other parts of the request should not be accessible?

[glassfishrobot]

@glassfishrobot Commented
gregwilkins said:
definite agree that using the request methods asychronously is not reliable.

I'm not sure that access should be prohibited, but the javadoc should at least point out that the values returned may change (due to dispatches) and that the memory barriers for such changes are undefined.

[glassfishrobot]

@glassfishrobot Commented
This issue was imported from java.net JIRA SERVLET_SPEC-41