| Hi,
I have several WebObjects 5.3.2 applications deployed in production running with Java 5, and I've found something worrying with stateless components. By the way, these applications are set to allow concurrent request.
I have an heavily used stateless component managing is own bindings synchronisation:
public class Cell extends WOComponent { // Private instance variable private Boolean _flag;
// Code removed for clarity... [...]
public boolean flag() { if(_flag == null) { // Initialize _flag to a Boolean instance: it can't be set to null [...] }
return _flag.booleanValue(); }
public boolean isStateless() { return true; }
public void reset() { super.reset();
// The only place in the variable is set to null _flag = null; }
public boolean synchronizesVariablesWithBindings() { return false; } }
But sometimes (less than 1% of concurrent requests), I get a NullPointerException on the "return _flag.booleanValue();" line! And this is only an evidence of the problem: sometimes I also get incorrect values. Normally, this can't be the case according to the WOComponent documentation:
<< Note that a stateless component's instance variables will remain valid for the duration of the phase (takeValuesFromRequest , invokeAction , appendToResponse ); this lets you use instance variables in the stateless components to hold things analogous to items in a WORepetition. >>
And IIRC, WebObjects use only one instance of a stateless component per thread. So I must conclude another thread called "reset()" on the same component instance, violating the WOComponent contract quoted above. This seems to be a bug in WebObjects... Can someone confirm this? Is their any workaround? I've tried to syncronize the stateless component in the appendToResponse method, but it leads to deadlocks on concurrent requests...
Kind regards,
-- Francis Labrie Saint-Bruno-de-Montarville, Quebec, Canada
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