Just a non-well-informed thought: Are you not able to cache the results and combine multiple requests that would return the same results into a single first call and subsequent requests would read from the cache? That is to say comparing 50 calls to 300 calls, the likelihood of more of the requests actually asking the same thing and getting the same results is higher, so calling the DNSLookup only once for all the unique requests should result in a speed improvement.
Stephen Dickason Senior Developer - Managed Services Email: sdicka...@elcb.co.za ELCB Information Services (Pty) Ltd Customer Service Email e...@elcb.co.za * www.elcb.co.za E A S T L O N D O N Tel: +27(43) 704 0700 Fax: +27(43) 704 0701 J O H A N N E S B U R G Tel: +27(11) 879 6179 Fax: +27(11) 454 0384 P O R T E L I Z A B E T H Tel: +27(41) 373 0529 Fax: +27(86) 650 0135 Disclaimer -----Original Message----- From: TWSocket [mailto:twsocket-boun...@lists.elists.org] On Behalf Of Max Terentiev Sent: 18 September 2015 02:07 To: ICS support mailing Subject: [twsocket] TWSocket.Connet/GetHostByName bottleneck Hi, I develop smtp relay server using ICS. And I notice very big performance hit if many TSmtpCli's connects to remote MX server in parallel ! I use TDnsQuery to resolve domain's MX server then supply result to TSmtpCli. If I use 100+ TSmtpCli instances most of them waits for OnRequestDone after TSmtpCli.Connect call. Looks like problem in TWSocket.DnsLookup because they call WSocket_Synchronized_WSAAsyncGetHostByName but MSDN say: "The WSAAsyncGetHostByName function is not designed to provide parallel resolution of several names." So, if 100 TSmtpCli's perform Connect they can't do it in parallel because WSAAsyncGetHostByName works sequentially. So 300+ TSmtpCli's works slower than 50 TSmtpCli's because waits for WSAAsyncGetHostByName queue. Can you suggest some workaround to avoid this problem ? At this time I see this way: 1. Use TDNSQuery.MXLookup to resolve MX, then TDNSQuery.ALookup to resolve MX's IP. Then supply resolved MX IP to TSmtpCli to avoid GetHostByName. 2. Cache both MX and A results in my own DNS cache. But maybe you can suggest more efficient way ? Maybe some tuning or secret option in ICS ? Thanks for help ! --- With best regards, Max Terentiev. Business Software Products. AMS Development Team. supp...@bspdev.com -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
