docstr: Check that the work is distributed among all workers
docstr_tok: ["Check","that","the","work","is","distributed","among","all","workers"]
code: def test_all_workers_are_active_processes(self):
      """Check that the work is distributed among all workers"""
      WORKERS_COUNT = 10
  
      # Testing only ProcessPool since only it has the mechanism that waits for all workers to come online before
      # start finishes
      pool = ProcessPool(WORKERS_COUNT)
  
      pool.start(WorkerIdGeneratingWorker)
      for _ in range(100):
          pool.ventilate()
  
      active_worker_ids = [pool.get_results() for _ in range(100)]
      self.assertEqual(
          set(range(WORKERS_COUNT)), set(active_worker_ids)
      )
  
      pool.stop()
      pool.join()
  
imports: import time
  import unittest
  import numpy
  from multiprocessing import Process, Manager
  from psutil import pid_exists
  from petastorm.workers_pool import EmptyResultError
  from petastorm.workers_pool.dummy_pool import DummyPool
  from petastorm.workers_pool.process_pool import ProcessPool
  from petastorm.workers_pool.tests.stub_workers import CoeffMultiplierWorker, WorkerIdGeneratingWorker, WorkerMultiIdGeneratingWorker, SleepyWorkerIdGeneratingWorker, ExceptionGeneratingWorker_5, PreprogrammedReturnValueWorker
  from petastorm.workers_pool.thread_pool import ThreadPool
label_desc: Use image node_id 5 for calling the TestWorkersPool obj's underlying member method code with example usage: obj.test_all_workers_are_active_processes() without return types