Device server takes 10 s to start when a local interface address has no reverse DNS answer

Development C++
1

Hi folks,

Well the title says what the problem is.

On my machine it took 10s for a very simple Tango server to start.

The problem was caused by a network interface that has no reverse DNS answer

(docker0 here): Tango looks up every local address at startup and waits out

the full 10s resolver timeout on that one.

I had AI generate a script to reproduce it with a dummy pyTango server and

a patched `getnameinfo()`:

git clone https://gitlab.esrf.fr/denolf/tango-startup-dns.git

cd tango-startup-dns

./reproduce.sh

Details in READE.md (obviously all AI).

Cheers,

Wout

2

Hi Wout,

I have the same issue, caused by multiple NICs and IP aliases. My workaround on Windows 11 is to set a higher metric (=>lower value) for the Tango-related NIC. See this issue #1216. Here is my PowerShell funcition for switching the NIC metrics from PS terminal:

function ToggleLabNICMetric {
  $NIC            = "LABOR-NIC"
  $MetricTango    = 1
  $MetricInternet = 100

  # Metrik lesen - kein Admin noetig
  $current = (Get-NetIPInterface -InterfaceAlias $NIC -AddressFamily IPv4).InterfaceMetric

  if ($current -eq $MetricTango) {
	  $new  = $MetricInternet
	  $mode = "Internet-Modus (UNI-NIC primaer)"
  } else {
	  $new  = $MetricTango
	  $mode = "TANGO-Modus  (LABOR-NIC primaer)"
  }

  if (-not
([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)) {
	  Write-Host "Admin-Rechte erforderlich - UAC-Dialog folgt..." -ForegroundColor Yellow
	  $cmd = "Set-NetIPInterface -InterfaceAlias '$NIC' -AddressFamily IPv4 -InterfaceMetric $new; " +
			 "ipconfig /flushdns | Out-Null; " +
			 "Write-Host 'LABOR-NIC Metrik: $current -> $new  |  $mode' -ForegroundColor Green; " +
			 "Start-Sleep 2"
	  Start-Process powershell.exe -ArgumentList "-NoProfile -ExecutionPolicy Bypass -Command `"$cmd`"" -Verb RunAs
	  return  "LABOR-NIC Metrik = $new  |  $mode"
  }

  Set-NetIPInterface -InterfaceAlias $NIC -AddressFamily IPv4 -InterfaceMetric $new
  ipconfig /flushdns | Out-Null
}