The specified thread pool has been configured in association with the "GetData" Adapter Set and, in particular, with the "DEFAULT" Data Adapter (Note that a Data Adapter configured with no name takes the "DEFAULT" name).

When you see that message, it means that the tasks performed by the pool are very slow, or even blocked.
In particular, this pool is used to perform subscriptions and unsubscriptions to the associated Data Adapter. This may involve many invocations to the Data Adapter and also the Metadata Adapter and we assume that the blocks occur there.
You should just take a full thread dump of the Server JVM and this should allow you to find the points in which the threads are blocked.