Cq engine persistent map giving exception "Caused by: java.sql.SQLException: database is locked"

Question

I am trying to store my Java Cq engine map on disk. The map is huge and multiple threads are accessing it concurrently.

I am getting:

Caused by: java.sql.SQLException: database is locked

I am doing this to remove clear my heap space. Slow search is not problem.

DiskPersistence<PimcoImsModel, String> persistence = DiskPersistence.onPrimaryKeyInFile(PimcoImsModel.ID, new File(getSourceDb()));

memory = new ConcurrentIndexedCollection<PimcoImsModel> (persistence);