text: Title: New trails are not being initiated after one ends
  Body: **Describe the issue**:
  The new trails are not being created/started after one ends. It started with two processes and after one or both were ended, no new process started.
  
  **Environment**:
  - NNI version: 2.10
  - Python version: 3.10.6
  - PyTorch/TensorFlow version: 2.8
  - Is conda/virtualenv/venv used?: cuda 11.7
  
  
  **Configuration**:
   - Experiment config:
  searchSpaceFile: search_space.json
  trialCommand: python3 model.py  # NOTE: change "python3" to "python" if you are using Windows
  trialGpuNumber: 1
  trialConcurrency: 2
  
  
  maxExperimentDuration: 156h
  maxTrialNumber: 200
  tuner:
    name: TPE
    classArgs:
      optimize_mode: maximize
  trainingService:
    platform: local
    useActiveGpu: True
    GpuIndices: 0,2
  
  