DO
$$
DECLARE
  c INT;
  conn_str TEXT DEFAULT
    'host=localhost port=5418 user=merlin.moncure dbname=postgres sslmode=disable';
  conn_count INT DEFAULT 50;

  remaining INT;
  running BOOL[];

  conn TEXT;

  active INT DEFAULT 0;

  timer TIMESTAMPTZ;
  inner_timer TIMESTAMPTZ;

  returned TEXT[];
  _found BOOL;

  num_queries INT DEFAULT 20000;
  queries INT DEFAULT num_queries;

  v BOOL;
  r RECORD;


  _query TEXT DEFAULT 'SELECT 0';

BEGIN
  CREATE EXTENSION IF NOT EXISTS dblink;

  PERFORM dblink_connect(
    'test' || s,
    conn_str)
  FROM generate_series(1,conn_count) s;

  RAISE NOTICE 'classic';
  timer := clock_timestamp();

  LOOP
    IF queries = 0 AND active = 0
    THEN
      EXIT;
    END IF;

    _found := false;

    FOR c IN 1..conn_count
    LOOP
      conn := 'test' || c;

      IF running[c] IS TRUE
      THEN
        IF NOT dblink_is_busy(conn) = 1
        THEN
          _found := true;

          PERFORM * FROM dblink_get_result(conn) AS R(V TEXT);
          PERFORM * FROM dblink_get_result(conn) AS R(V TEXT);

          running[c] := false;
          active := active - 1;
        END IF;
      END IF;

      IF queries > 0
      THEN
        PERFORM dblink_send_query('test' || c, _query);
        running[c] := true;
        active := active + 1;
        queries := queries - 1;

        IF queries % 1000 = 0
        THEN
          RAISE NOTICE '% queries to go!', queries;
        END IF;
      END IF;
     END LOOP;

     IF NOT _found
     THEN
       PERFORM pg_sleep(.001);
    END IF;
  END LOOP;

  queries := num_queries;
  running := array_agg(false) FROM generate_series(1, conn_count);

  raise notice '%', clock_timestamp() - timer;
  timer := clock_timestamp();


  RAISE NOTICE 'modified';
  LOOP
    IF queries = 0 AND active = 0
    THEN
      EXIT;
    END IF;

    IF active > 0
    THEN
      returned := dblink_wait_for_query(1.0, false);

      FOREACH conn IN ARRAY returned
      LOOP
        PERFORM count(*) FROM dblink_get_result(conn) AS R(V TEXT);
        PERFORM * FROM dblink_get_result(conn) AS R(V TEXT);

        c := substring(conn, 5)::INT;

        active := active - 1;
        running[c] := false;
      END LOOP;
    END IF;

    IF queries > 0
    THEN
      FOR r IN
        SELECT * FROM
        (
          SELECT * FROM unnest(running) WITH ORDINALITY AS R(x, n)
        )
        WHERE x IS FALSE
      LOOP
        PERFORM dblink_send_query('test' || r.n, _query);

        running[r.n] := true;
        active := active + 1;
        queries := queries - 1;

        IF queries % 1000 = 0
        THEN
          RAISE NOTICE '% queries to go! % active', queries, active;
        END IF;

        IF queries = 0 THEN
          EXIT;
        END IF;
      END LOOP;
    END IF;
  END LOOP;

  raise notice '%', clock_timestamp() - timer;

  PERFORM dblink_disconnect('test' || s) FROM generate_series(1,conn_count) s;

END;
$$ LANGUAGE PLPGSQL;