Hi David,
In addition to interrupting the worker thread (which is a good idea). There are
a couple of useful things that you can do using the support from
java.util.concurrent. For example, setting a closed state:
@Component
public class MyClass {
private final AtomicBoolean closed = new AtomicBoolean();
@Activate
void start() {
new Thread(this::longStart).run()
}
@Deactivate
void stop() {
closed.set(true);
}
void longStart() {
for(int i = 0; i < 1000000; i++) {
if(closed.get()) {
break;
}
doSomething();
}
}
}
Also if your references are dynamic then you should treat them carefully
@Component
public class MyClass implements MySlowService {
private final AtomicReference<MyService> myRef = new AtomicReference<>();
@Reference(policy=DYNAMIC)
void setReference(MyService service) {
myRef.set(service)
}
void unsetReference(MyService service) {
// Note that it is *not* safe to just do a set null, see Compendium
112.5.12
myRef.compareAndSet(service, null);
}
public void longRunningTask() {
for(int i = 0; i < 1000000; i++) {
// This only works if the service object is not stateful, otherwise
we need
// to do a check and throw away an intermediate invalidated result
MyService myService = myRef.get();
doSomethingWithMyService(myService);
}
}
}
I hope you find these helpful.
Tim
> On 1 Aug 2018, at 05:44, David Leangen via osgi-dev <osgi-dev@mail.osgi.org>
> wrote:
>
>
> Hi!
>
> I am running into a situation where, what I think is happening is:
>
> Component A gets instantiated
> Component B
> - references A
> - gets satisfied once A is satisfied
> - kicks off a long-running process when one of its methods are called
> - the long-running process is run in a different thread, with a Promise
> Component A is no longer satisfied
> But
> - the long-running process is still running
> - the long-running process now references an invalid Component A
> - the long-running thread fails because of the invalid state of Component A
> Component B is no longer satisfied
>
>
> So, the long-running component messes things up, but its component has not
> yet shut down even though its process is still happily running in another
> thread.
>
> I can think of two possible solutions, but not sure which is best and not
> sure how to implement:
>
> 1) Figure out a way to share an ExecutorService between “related” components
> so that when one component
> shuts down it will signal to the other related components that their
> threads are now interrupted
>
> 2) In the long-running process, determine if the component that provides the
> required service
> is still active before continuing with the havoc-wreaking process
>
>
> Does this sound about right?
>
> How would I actually accomplish either of these?
>
>
> Thanks!
> =David
>
>
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