A wrapper of another {@link org.apache.lucene.index.MergeScheduler} that allowsto explicitly enable merge and disable on a thread local basis. The default is to have merges disabled.
This merge scheduler can be used to get around the fact that even though a merge policy can control that no new merges will be created as a result of a segment flush (during indexing operation for example), the {@link #merge(org.apache.lucene.index.IndexWriter,org.apache.lucene.index.MergeTrigger,boolean)}call will still be called, and can result in stalling indexing.