ServiceLoader double iterator issues

Posted by buge on Stack Overflow See other posts from Stack Overflow or by buge
Published on 2010-04-07T15:34:18Z Indexed on 2010/04/07 15:53 UTC
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Is this a known issue? I had trouble finding any search results.

When iterating over a ServiceLoader while an iteration already is in progress, the first iteration will be aborted. For example, assuming there are at least two implementations of Foo, the following code will fail with an AssertionError:

ServiceLoader<Foo> loader = ServiceLoader.load(Foo.class);
Iterator<Foo> iter1 = loader.iterator();
iter1.next();

Iterator<Foo> iter2 = loader.iterator();
while (iter2.hasNext()) {
    iter2.next();
}

assert iter1.hasNext();

This only seems to occur, if the second iterator really terminates. The code will succeed in this variation for example:

ServiceLoader<Foo> loader = ServiceLoader.load(Foo.class);
Iterator<Foo> iter1 = loader.iterator();
iter1.next();

Iterator<Foo> iter2 = loader.iterator();
iter2.next();

assert iter1.hasNext();

Is this a bug or a feature? :p

Is there a ticket for this already anywhere?

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