The "Objects" column (2nd column) shows the total number of instances for that class/package, and the retained size shows the size of that class and all of its members.
There are thus 70,000 TransportReplicationAction$ReroutePhase , and their total size is ~15.6 GB.
There are also 22,000 bulk requests:
3.8 million index requests:
Here is an example document:
However, my thread_pool.bulk.queue_size is only 50 for that node.
Additional info:
46 ingest/hot nodes
46 Logstash instances
thread_pool.bulk.queue_size: 50
thread_pool.bulk.size: 17
batch size for ES publish is 200 documents per request.
Each Logstash has 72 threads available for publishing.