[Ace-users] [ace-users] ACE not detecting connection closing with keepalive enabled

[Douglas C. Schmidt]

Hi Yan,

   Thanks for using the PRF.

>ACE VERSION: 5.6.1, 5.5.3, 5.5.4
>
>HOST MACHINE and OPERATING SYSTEM:
>Fedora core 5 linux
>
>TARGET MACHINE and OPERATING SYSTEM, if different from HOST:
>Pentium M 1.8Ghz gcc 4.1.1
>
>Official RPMs from http://dist.bonsai.com/ken/ace_tao_rpm/
>
>DOES THE PROBLEM AFFECT:
>EXECUTION
>
>AREA/CLASS/EXAMPLE AFFECTED:
>ACE_Svc_Handler
>
>SYNOPSIS:
>If peer is disconnected and data is sent to peer before the socket =
>"senses" the error, handle_close() is not called for very long time
>
>DESCRIPTION:
>I am running the same code on windows and linux using ACE.
>I set keepalive values on both platforms so that I can detect connection =
>tear-off fast. The class I use it in, is derived class of =
>ACE_Svc_Handler<ACE_SOCK_STREAM, ACE_MT_SYNCH> Here's the code for =
>setting the keepalive:
>#define PROBES_FREQ_SECONDS 1
>#define KEEP_ALIVE_PROBES_SECONDS 4
>
>	option =3D 1;
>	peer().set_option(SOL_TCP, TCP_KEEPALIVE, &option, sizeof(option)); =
>#ifdef __linux__
>	// set keepalive idle time (wait IDLE seconds)
>	option =3D KEEP_ALIVE_PROBES_SECONDS;
>	peer().set_option(SOL_TCP, TCP_KEEPIDLE, &option, sizeof(option));
>
>	// set interval between probes (send CNT probes)
>	option =3D 3;
>	peer().set_option(SOL_TCP, TCP_KEEPCNT, &option, sizeof(option));
>
>	// set interval between probes (send probes with INTVL seconds apart)
>	option =3D PROBES_FREQ_SECONDS;
>	peer().set_option(SOL_TCP, TCP_KEEPINTVL, &option, sizeof(option)); =
>#endif // __linux__
>
>#ifdef _WIN32
>	// defined in MSTcpIP.h
>	struct tcp_keepalive settings, returned;
>	DWORD dwBytes;
>
>	memset(&settings, 0, sizeof(settings));
>	memset(&returned, 0, sizeof(returned));
>
>	settings.onoff =3D 1; // On
>	// how often to send keepalive probes
>	settings.keepalivetime =3D KEEP_ALIVE_PROBES_SECONDS * 1000;
>	// Resend if No-Reply
>	settings.keepaliveinterval =3D PROBES_FREQ_SECONDS * 1000;
>
>	int res =3D ACE_OS::ioctl(peer().get_handle(), SIO_KEEPALIVE_VALS,
>		reinterpret_cast<void*>(&settings), sizeof(settings),
>		reinterpret_cast<void*>(&returned), sizeof(returned), &dwBytes,
>		NULL, NULL);
>#endif
>
>This works fine both on windows and linux - when I disconnect peer's =
>network cable, handle_close() is called within 4-8 seconds.
>If I send something through that socket before handle_close() is called, =
>but after I disconnected the peer's network cable, handle_close() is =
>sometimes called after 20 minutes or so. This behavior is observed only =
>on linux, on windows my code works exactly as expected - connection =
>failure is detected always. The only platform dependent code I have is =
>stated above. Everything else is the same on windows and linux. The =
>version it worked for on windows is 5.5.4. I tried 5.5.4, 5.5.3 and =
>5.6.1 on linux and got the same result.
>
>
>Hope you can help by either clarifying something I'm missing or if this =
>is a bug in ACE.

This sounds like the behavior of Linux, not ACE.  I recommend you try
using the native C APIs to see if you get the same behavior.

Thnaks,

        Doug
-- 
Dr. Douglas C. Schmidt                       Professor and Associate Chair
Electrical Engineering and Computer Science  TEL: (615) 343-8197
Vanderbilt University                        WEB: www.dre.vanderbilt.edu/~schmidt
Nashville, TN 37203                          NET: d.schmidt at vanderbilt.edu