hi, how can i decrease the connection usage-counter check out ???

is it possible to block an connection to handle an SQL transactions? so no other SELECT or something else with an implicit COMMIT will break an transaction?

regards, volker.

According to some issues when ConnectionState enum (of $connectionFactory Closure/Class, which creates connection adapter) isn't Ready and retryWithDelay() function is called repeatedly.

I used to debug calls that used in your test.php file.

If you want better code readability you can use this variation of retryWithDelay() function (notice additional $selectConnectionDeferred):

protected function retryWithDelay(Deferred $deferred = null): \React\Promise\Promise
{
      if ($this->retryLimit !== null && $this->retryLimit < 1) {
          throw new ConnectionPoolException('No available connection to use');
      }

      $deferred ??= new Deferred();

      if (!$this->awaiting->contains($deferred)) {
          $this->awaiting->attach($deferred, 0);
      }

      if ($this->awaiting[$deferred] === $this->retryLimit) {
          $this->awaiting->detach($deferred);
          throw new ConnectionPoolException("No available connection to use; $this->retryLimit attempts were made");
      }

      $selectConnectionDeferred = new Deferred();

      $this->loop->addTimer($this->retryEverySec, function () use ($deferred, $selectConnectionDeferred) {
          $connectionAdapter = $this->selectConnection();

          if ($connectionAdapter) {
              $this->awaiting->detach($deferred);
              $selectConnectionDeferred->resolve(true);
              $deferred->resolve($connectionAdapter);
              return;
          }

          $this->awaiting[$deferred] = $this->awaiting[$deferred] + 1;
          $selectConnectionDeferred->resolve(false);
      });

      return $selectConnectionDeferred->promise()->then(function($connectionSelected) use ($deferred) {
          return $connectionSelected ? $deferred->promise() : $this->retryWithDelay($deferred);
      });
}