Adam,
Thanks for the contribution. Your technique is better than what is
currently used and will be applied to the code. The one thing that appears
to be missing is that you do not change the code
} else if (scopeLock == context) {
context.setAttribute (targetID, targetObject);
}
With your other change decribed below, scopeLock will never equal context,
so the instance will never be registered and you will create a new instance
with each invocation, effectively making the service have request scope.
Scott Nichol
----- Original Message -----
From: "Adam Moore" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, July 11, 2002 10:29 AM
Subject: RE: Constructor Deadlock
> Scenario: We have a class that implements a SOAP service. Service scope
is
> set to "application". In the constructor of that class we make a call to
a
> different service that is running on the same machine. Since these are
> different services with different service ids everything should run fine,
> since there are no recursion. However, a deadlock occurs when trying to
> invoke a call on the another service. The problem does not appear when you
> call another service from any service method, it only appears during
object
> creation.
>
> Reason: The block of code that gets the target object for a service has a
> synchronized block with an Object scopeLock ie: synchronized(scopeLock){}.
> If the service is of type "application", the scopeLock object is set to
the
> ServletContext object. Since there is only one ServletContext per servlet
> per JVM, we will be blocked if we try to call non-created service with
> "application" scope from the constructor of another service with same
scope.
> Everything goes fine if we call a service that is on another machine. SOAP
> may contain several services on a machine and the service location should
> not influence the behavior of other services which depend on it.
>
> Fix: When retrieving the target object with application scope, do not
> block on the ServletContext. Instead, block on the service providing
class.
> This will allow calls to be made to different services but still provide
the
> necessary blocking on nested service calls to the same service providing
> class and only one instance of the service will be created.
>
> Code fix: This bug was fixed by changing the value of the scopeLock when
the
> scope is of type "application." Currently the scopeLock for a type
> "application" is the ServletContext object, to fix the deadlock the
> scopeLock should be changed to the service provider class.
>
> The code fix involves modifying the following code snipet:
>
> Class: org.apache.soap.server.http.ServerHTTPUtils.java
> Method: getTargetObject (ServiceManager serviceManager,
> DeploymentDescriptor dd,
> String targetID,
> HttpServlet thisServlet,
> HttpSession session,
> SOAPContext ctxt,
> ServletContext context)
>
> 1. Add an additional throw clause to the method to throw
> ClassNotFoundException.
>
> 2. (File: org.apache.soap.server.http.ServerHTTPUtils.java,
Line
> #247)
>
> Replace:
>
> else if (scope == DeploymentDescriptor.SCOPE_APPLICATION) {
> scopeLock = context;
> }
>
> With:
>
> else if (scope == DeploymentDescriptor.SCOPE_APPLICATION) {
> scopeLock = Class.forName(className);
> }
>
> -----Original Message-----
> From: Adam Moore [mailto:[EMAIL PROTECTED]]
> Sent: Dienstag, 9. Juli 2002 17:36
> To: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]
> Subject: Constructor Deadlock
>
>
>
> I have a class that implements a SOAP service. In the constructor of
> that class, I want to make a SOAP call (using the Apache "Call" class)
> to a different service that is running in the same JVM, and everything
> hangs. Looking with jdb, it appears that the call is awaiting the
> response from the doPost(), but the called service is never actually
> invoked. Neither service can be called at this point from an external
> client.
>
> Environment:
>
> Sun JDK 1.3.1
> Tomcat 3.3.1
> Apache SOAP 2.3.1
>
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>
>
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