RHV: multiple operations failing, sanlock consuming a lot of memory and unresponsive hosts.

Issue

• Cannot migrate Virtual Machines to particular hypervisors
• Cannot start Virtual Machines to particular hypervisors
• Hypervisors in Not Responding state, with below message repeating:

Get Host Capabilities failed: Not enough resources: {'resource': 'jsonrpc', 'current_tasks': 80, 'reason': 'Too many tasks"

• Creating VMs from template, copying disks fail with:

vdsm.storage.exception.AcquireHostIdFailure: Cannot acquire host id: ("Timeout acquiring host id, cannot acquire Lease(name='fc439026-2696-4415-a548-97171de11b70', path='/dev/3050b111-d0e4-473f-8e04-1531ed4445e6/leases', offset=212860928) (id=6)",)

• Hypervisor is running out of memory, sanlock is using too much memory.