Reindexing a synchronous index by simply setting reindex property to true results in a synchronous operation which can cause an Oak instance to hang. To avoid this situation send indexing to a background thread. To do this, follow the steps below:
Note: Only the 'async="async-reindex"' will be removed as that controls which thread the indexing will happen on. The 'reindex-async' property is just a configuration flag which will not change automatically. The idea is that you'd set it once for the specific index definitions controlling all future reindexing. That is then expected that it stay in there and then you won't need to touch it again.
Remove the reindexing checkpoint (AEM 6.2 and older versions only)
During the process of async reindexing, a repository checkpoint is created. Once the indexing task has completed, it must be released as described below, to ensure smooth Revision Garbage Collection later on :
First, open the CheckpointManager MBean: