Running multiple environments in parallel using same container failed with container name conflict error.

[xeronm]

Hi,

I've faced with the following problem.
I use two environment with postgres container.
When I run in parallel mode tox -p, only first environment that use container succeeded, the second fails with container name conflict error.

docker.errors.APIError: 409 Client Error for http+docker://localhost/v1.43/containers/create?name=db-tox-31039: Conflict ("Conflict. The container name "/db-tox-31039" is already in use by container "9e91cc7f480abcc9ac28a8f47eb4520a6de4db3811b8c706d4371d80330ae97e". You have to remove (or rename) that container to be able to reuse that name.")
  flake: OK ✔ in 8.25 seconds
  py39-dj42-sqlite: OK ✔ in 1 minute 5.1 seconds
  py310-dj42-sqlite: OK ✔ in 1 minute 11.35 seconds
  py39-dj42-sqlite: OK (65.10=setup[5.71]+cmd[3.62,52.08,1.10,1.23,1.35] seconds)
  py39-dj42-postgres: OK (81.13=setup[11.72]+cmd[67.23,0.74,0.76,0.68] seconds)
  py310-dj42-sqlite: OK (71.35=setup[7.10]+cmd[3.36,57.53,0.91,1.00,1.45] seconds)
  py310-dj42-postgres: FAIL code 2 (7.19 seconds)
  isort: OK (7.47=setup[5.58]+cmd[1.90] seconds)
  flake: OK (8.25=setup[5.71]+cmd[2.54] seconds)
  evaluation failed :( (81.48 seconds)

The problem is in

def runas_name(container_name: str, pid: Optional[int] = None) -> str:
    ...
    pid = pid or os.getpid()
    return f"{container_name}-tox-{pid}"

Could you consider using either thread Id instead process Id or concatenate {env_name} with process id?

def runas_name(container_name: str, pid: Optional[int] = None) -> str:
    ...
    pid = pid or threading.get_ident()
    return f"{container_name}-tox-{pid}"