I’ve realized that I misdiagnosed your problem.
When I tried to reproduce the error you’re getting, I realized that I had been thinking of the other error that occurs when a process cannot find a checked out connection. It looks like this:
11:14:40.287 [error] Task #PID<0.244.0> started from #PID<0.241.0> terminating
** (DBConnection.OwnershipError) cannot find ownership process for #PID<0.244.0>.
When using ownership, you must manage connections in one
of the four ways:
[...it goes on for a while...]
However, the error you’re getting must be caused by the test process exiting before another process stopped using the DB connection. I was only able to reproduce this as follows:
test "Task.Supervisor.async_stream" do
enum = [1, 2, 3]
stream =
Task.Supervisor.async_stream_nolink(
Module.TaskSupervisor,
enum,
fn item -> my_func(item, 2) end,
ordered: false,
max_concurrency: 1
)
_result = Enum.to_list(stream)
# We have to sleep here to allow the process spawned by my_func()
# to enter a transaction
on_exit(fn ->
Process.sleep(100)
end)
end
defp my_func(user_id, _n) do
Project.Repo.get(Project.User, user_id)
# I could only get the error to occur when I spawned another process here.
spawn(fn ->
# This transaction starts before the test process exits but it sleeps for a while
# to let the test process terminate. Then, when Project.Repo.get() is called, it'll
# raise the error
# Postgrex.Protocol (#PID<0.210.0>) disconnected: ** (DBConnection.ConnectionError) owner #PID<0.241.0> exited
Project.Repo.transaction(fn ->
Process.sleep(100)
Project.Repo.get(Project.User, user_id)
end)
end)
end
The full error I’m getting looks a bit different from yours, but I think it happen in a similar circumstance:
11:19:10.365 [error] Postgrex.Protocol (#PID<0.210.0>) disconnected: ** (DBConnection.ConnectionError) owner #PID<0.241.0> exited
Client #PID<0.247.0> is still using a connection from owner at location:
(elixir) lib/process.ex:228: Process.sleep/1
test/sandbox_test.exs:29: anonymous fn/1 in SandboxTest.my_func/2
(ecto_sql) lib/ecto/adapters/sql.ex:814: anonymous fn/3 in Ecto.Adapters.SQL.checkout_or_transaction/4
(db_connection) lib/db_connection.ex:1349: DBConnection.run_transaction/4
The connection itself was checked out by #PID<0.247.0> at location:
In the end, you were right about your tests running with async: false since that the default, so my analysis was wrong in that regard. However, I think there’s something else going on in your test suite outside of the code snippets you’ve shared so far.
