The new IndexWriter in Lucene 4 uses a limited set of affinity tokens to hand to each thread.
The default is only 8, which gets exhausted quite easily in the way we use the IndexWriter; also there seems to be no high penalty in proposing an higher value other than a slight memory cost.
I'm proposing a default of 32 and to make this a configurable setting.
I've actually decided to not change the default, as we never do that normally.
32 seems to be a better value for Infinispan only, so Infinispan will have the option to change it but we don't need to do that in the engine.