On increasing concurrent http calls, thread count (akka.actor.default-dispatcher) keeps increasing causing readiness-probe to timeout

Hi all,
We observe that on increasing concurrent http calls to our service, thread count (akka.actor.default-dispatcher) keeps increasing (see screenshot from visualVM). Also after the requests stop, the thread count don’t go down. And most of these remain in PARK state.
Is this proportional increase of threads an expected behaviour? How do we control this and reuse the same actors or kill the actors after request has been served.

I’m running the shopping-cart example from lagom-samples.

  akka.actor.default-dispatcher {
      executor = "fork-join-executor"
      fork-join-executor {
           parallelism-min = 2
           parallelism-factor = 1.0
           parallelism-max = 6
        throughput = 1

Edit: Using thread-pool-executor as akka.actor.default-dispatcher stops serving any requests after multiple (20-30) concurrent requests. Even console goes unresponsive.

default-dispatcher  {
     type = Dispatcher
     executor = default-executor
     throughput = 1
     default-executor = { fallback = thread-pool-executor }
     thread-pool-executor = {
         keep-alive-time = 60s
         core-pool-size-min = 8
         core-pool-size-factor = 3.0
         core-pool-size-max = 64
         max-pool-size-min = 8
         max-pool-size-factor = 3.0
         max-pool-size-max = 64
         task-queue-size = -1
         task-queue-type = linked
         allow-core-timeout = on

In the akka docs introduction it highlights “Millions of actors can be efficiently scheduled on a dozen of threads”. So in that case why would we need to create threads proportional to number of concurrent requests

Cross-posted from In lagom: on increasing concurrent http calls, thread count (akka.actor.default-dispatcher) keeps increasing. How to control this behaviour? - Stack Overflow

It seems using blocking get for read-side DB calls was causing the spawn of new actors.
This answer from James Peter helped: https://stackoverflow.com/a/67053784/14278779