# [PATCH] daemon: enable SO_KEEPALIVE for all sockets 4 messages from 2016-05-25 to 2016-05-25. Participants: Eric Wong, Jeff King, Junio C Hamano. Thread: https://gitlist.dev/t/42446 ## Eric Wong, 2016-05-25 03:15 Subject: [PATCH] daemon: enable SO_KEEPALIVE for all sockets Message-ID: <20160525031505.5720-1-e@80x24.org> URL: https://gitlist.dev/e/20160525031505.5720-1-e%4080x24.org ``` While --init-timeout and --timeout options exist and I've never run git-daemon without them, some users may forget to set them and encounter hung daemon processes when connections fail. Enable socket-level timeouts so the kernel can send keepalive probes as necessary to detect failed connections. Signed-off-by: Eric Wong --- daemon.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/daemon.c b/daemon.c index 8d45c33..46dddac 100644 --- a/daemon.c +++ b/daemon.c @@ -669,6 +669,15 @@ static void hostinfo_clear(struct hostinfo *hi) strbuf_release(&hi->tcp_port); } +static void set_keep_alive(int sockfd) +{ + int ka = 1; + + if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) + logerror("unable to set SO_KEEPALIVE on socket: %s", + strerror(errno)); +} + static int execute(void) { char *line = packet_buffer; @@ -681,6 +690,7 @@ static int execute(void) if (addr) loginfo("Connection from %s:%s", addr, port); + set_keep_alive(0); alarm(init_timeout ? init_timeout : timeout); pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0); alarm(0); @@ -951,6 +961,8 @@ static int setup_named_sock(char *listen_addr, int listen_port, struct socketlis continue; } + set_keep_alive(sockfd); + if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) { logerror("Could not bind to %s: %s", ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen), @@ -1010,6 +1022,8 @@ static int setup_named_sock(char *listen_addr, int listen_port, struct socketlis return 0; } + set_keep_alive(sockfd); + if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) { logerror("Could not bind to %s: %s", ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)), ``` ## Jeff King, 2016-05-25 22:42 Subject: Re: [PATCH] daemon: enable SO_KEEPALIVE for all sockets Message-ID: <20160525224235.GE13776@sigill.intra.peff.net> URL: https://gitlist.dev/e/20160525224235.GE13776%40sigill.intra.peff.net In-Reply-To: <20160525031505.5720-1-e@80x24.org> ``` On Wed, May 25, 2016 at 03:15:05AM +0000, Eric Wong wrote: > While --init-timeout and --timeout options exist and I've never > run git-daemon without them, some users may forget to set them > and encounter hung daemon processes when connections fail. > Enable socket-level timeouts so the kernel can send keepalive > probes as necessary to detect failed connections. Makes sense. I wondered if there were any portability issues here, but it looks like the same code is found on the client side (but we'd still want it here for cases where the client thinks the connection is dead but the server does not realize it). -Peff ``` ## Junio C Hamano, 2016-05-25 22:44 Subject: Re: [PATCH] daemon: enable SO_KEEPALIVE for all sockets Message-ID: URL: https://gitlist.dev/e/xmqq37p5zrjk.fsf%40gitster.mtv.corp.google.com In-Reply-To: <20160525031505.5720-1-e@80x24.org> ``` Eric Wong writes: > While --init-timeout and --timeout options exist and I've never > run git-daemon without them, some users may forget to set them > and encounter hung daemon processes when connections fail. > Enable socket-level timeouts so the kernel can send keepalive > probes as necessary to detect failed connections. > > Signed-off-by: Eric Wong > --- This makes sense as a follow-up to e47a8583 (enable SO_KEEPALIVE for connected TCP sockets, 2011-12-06), I think. ``` ## Eric Wong, 2016-05-25 23:11 Subject: Re: [PATCH] daemon: enable SO_KEEPALIVE for all sockets Message-ID: <20160525231114.GA20691@dcvr.yhbt.net> URL: https://gitlist.dev/e/20160525231114.GA20691%40dcvr.yhbt.net In-Reply-To: ``` Junio C Hamano wrote: > This makes sense as a follow-up to e47a8583 (enable SO_KEEPALIVE for > connected TCP sockets, 2011-12-06), I think. Yes, a15d069a19867 for http, too; hat trick :> Anyways, it might've helped Savannah when they had networking problems: http://mid.gmane.org/20160524214102858920068@bob.proulx.com They might be running an old version that didn't send keepalive heartbeats during packing, too. But SO_KEEPALIVE will still help during init when --init-timeout is not set. Perhaps it also makes sense to squash the following xinetd setting into giteveryday.txt, too; since some users could be running out-of-date git but reading new documentation on the web: --- a/Documentation/giteveryday.txt +++ b/Documentation/giteveryday.txt @@ -390,6 +390,7 @@ service git server = /usr/bin/git-daemon server_args = --inetd --export-all --base-path=/pub/scm log_on_failure += USERID + flags = KEEPALIVE } ------------ + ```