Re: Implement support for TCP_KEEPCNT, TCP_KEEPIDLE, TCP_KEEPINTVL

Where are we on this? I do think it solves a problem that some are
having, and it seems it would detect a disconnected client and abort a
long running query.

I am not very excited about adding four more GUC variables, and I am
thinking we could just have it use the OS defaults and see if we need
more later, so that would add only one GUC.

It compiles/tests fine on my BSD system.

---------------------------------------------------------------------------

Oliver Jowett wrote:
> Tom Lane wrote:
> > Oliver Jowett <oliver(at)opencloud(dot)com> writes:
> >
> >>Tom Lane wrote:
> >>
> >>>I'm not convinced that Postgres ought to provide
> >>>a way to second-guess the TCP stack ...
> >
> >
> >>Would you be ok with a patch that allowed configuration of the
> >>TCP_KEEPCNT / TCP_KEEPIDLE / TCP_KEEPINTVL socket options on backend
> >>sockets?
> >
> >
> > [ shrug... ] As long as it doesn't fail to build on platforms that
> > don't offer those options, I couldn't complain too hard. But do we
> > really need all that?
>
> Here's a patch that adds four new GUCs:
>
> tcp_keepalives (defaults to on, controls SO_KEEPALIVE)
> tcp_keepalives_idle (controls TCP_KEEPIDLE)
> tcp_keepalives_interval (controls TCP_KEEPINTVL)
> tcp_keepalives_count (controls TCP_KEEPCNT)
>
> They're ignored for AF_UNIX connections and when running standalone.
>
> tcp_keepalives_* treat 0 as "use system default". If the underlying OS
> doesn't provide the TCP_KEEP* socket options, the GUCs are present but
> reject any value other than 0.
>
> SHOW reflects the currently-in-use value or 0 if not applicable or not
> known. i.e. if you set it to 0 and you have the socket options
> available, SHOW will show the result of getsockopt() which is non-zero.
>
> A default install on my Linux system produces:
>
> template1=# show all;
> name | setting
>
> --------------------------------+----------------------------------------------
> [...]
> tcp_keepalives | on
> tcp_keepalives_count | 9
> tcp_keepalives_idle | 7200
> tcp_keepalives_interval | 75
> [...]
>
> I haven't had a chance to check it builds on other systems or to test
> that this handles actual network failures nicely yet.
>
> -O

> Index: doc/src/sgml/runtime.sgml
> ===================================================================
> RCS file: /projects/cvsroot/pgsql/doc/src/sgml/runtime.sgml,v
> retrieving revision 1.315
> diff -c -r1.315 runtime.sgml
> *** doc/src/sgml/runtime.sgml 23 Apr 2005 03:27:40 -0000 1.315
> --- doc/src/sgml/runtime.sgml 3 May 2005 01:44:02 -0000
> ***************
> *** 889,894 ****
> --- 889,961 ----
> </listitem>
> </varlistentry>
>
> + <varlistentry id="guc-tcp-keepalives" xreflabel="tcp_keepalives">
> + <term><varname>tcp_keepalives</varname> (<type>boolean</type>)</term>
> + <indexterm>
> + <primary><varname>tcp_keepalives</> configuration parameter</primary>
> + </indexterm>
> + <listitem>
> + <para>
> + Controls the use of TCP keepalives on client connections. When enabled,
> + idle connections will be periodically probed to check that the client
> + is still present. If sufficient probes are lost, the connection will
> + be broken. This option is ignored for connections made via a
> + Unix-domain socket.
> + </para>
> + </listitem>
> + </varlistentry>
> +
> + <varlistentry id="guc-tcp-keepalives-idle" xreflabel="tcp_keepalives_idle">
> + <term><varname>tcp_keepalives_idle</varname> (<type>integer</type>)</term>
> + <indexterm>
> + <primary><varname>tcp_keepalives_idle</> configuration parameter</primary>
> + </indexterm>
> + <listitem>
> + <para>
> + On systems that support the TCP_KEEPIDLE socket option, specifies the
> + number of seconds between sending keepalives on an otherwise idle
> + connection. A value of 0 uses the system default. If TCP_KEEPIDLE is
> + not supported, this parameter must be 0. This option is ignored for
> + connections made via a Unix-domain socket, and will have no effect
> + unless the <varname>tcp_keepalives</varname> option is enabled.
> + </para>
> + </listitem>
> + </varlistentry>
> +
> + <varlistentry id="guc-tcp-keepalives-interval" xreflabel="tcp_keepalives_interval">
> + <term><varname>tcp_keepalives_interval</varname> (<type>integer</type>)</term>
> + <indexterm>
> + <primary><varname>tcp_keepalives_interval</> configuration parameter</primary>
> + </indexterm>
> + <listitem>
> + <para>
> + On systems that support the TCP_KEEPINTVL socket option, specifies how
> + long, in seconds, to wait for a response to a keepalive before
> + retransmitting. A value of 0 uses the system default. If TCP_KEEPINTVL
> + is not supported, this parameter must be 0. This option is ignored
> + for connections made via a Unix-domain socket, and will have no effect
> + unless the <varname>tcp_keepalives</varname> option is enabled.
> + </para>
> + </listitem>
> + </varlistentry>
> +
> + <varlistentry id="guc-tcp-keepalives-count" xreflabel="tcp_keepalives_count">
> + <term><varname>tcp_keepalives_count</varname> (<type>integer</type>)</term>
> + <indexterm>
> + <primary><varname>tcp_keepalives_count</> configuration parameter</primary>
> + </indexterm>
> + <listitem>
> + <para>
> + On systems that support the TCP_KEEPCNT socket option, specifies how
> + many keepalives may be lost before the connection is considered dead.
> + A value of 0 uses the system default. If TCP_KEEPINTVL is not
> + supported, this parameter must be 0. This option is ignored for
> + connections made via a Unix-domain socket, and will have no effect
> + unless the <varname>tcp_keepalives</varname> option is enabled.
> + </para>
> + </listitem>
> + </varlistentry>
> +
> </variablelist>
> </sect3>
> <sect3 id="runtime-config-connection-security">
> Index: src/backend/libpq/pqcomm.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql/src/backend/libpq/pqcomm.c,v
> retrieving revision 1.176
> diff -c -r1.176 pqcomm.c
> *** src/backend/libpq/pqcomm.c 22 Feb 2005 04:35:57 -0000 1.176
> --- src/backend/libpq/pqcomm.c 3 May 2005 01:44:03 -0000
> ***************
> *** 87,93 ****
> #include "libpq/libpq.h"
> #include "miscadmin.h"
> #include "storage/ipc.h"
> !
>
> /*
> * Configuration options
> --- 87,93 ----
> #include "libpq/libpq.h"
> #include "miscadmin.h"
> #include "storage/ipc.h"
> ! #include "utils/guc.h"
>
> /*
> * Configuration options
> ***************
> *** 577,582 ****
> --- 577,583 ----
> if (!IS_AF_UNIX(port->laddr.addr.ss_family))
> {
> int on;
> + socklen_t size;
>
> #ifdef TCP_NODELAY
> on = 1;
> ***************
> *** 587,599 ****
> return STATUS_ERROR;
> }
> #endif
> ! on = 1;
> ! if (setsockopt(port->sock, SOL_SOCKET, SO_KEEPALIVE,
> ! (char *) &on, sizeof(on)) < 0)
> {
> ! elog(LOG, "setsockopt(SO_KEEPALIVE) failed: %m");
> return STATUS_ERROR;
> }
> }
>
> return STATUS_OK;
> --- 588,645 ----
> return STATUS_ERROR;
> }
> #endif
> !
> ! if (pq_setkeepalives(tcp_keepalives, port) != STATUS_OK)
> ! return STATUS_ERROR;
> !
> ! /* Grab default keepalive values, then apply
> ! * our GUC settings.
> ! */
> ! #ifdef TCP_KEEPIDLE
> ! if (getsockopt(port->sock, SOL_TCP, TCP_KEEPIDLE,
> ! (char *) &port->default_keepalives_idle, &size) < 0)
> ! {
> ! elog(LOG, "getsockopt(TCP_KEEPIDLE) failed: %m");
> ! return STATUS_ERROR;
> ! }
> ! #else
> ! port->default_keepalives_idle = 0;
> ! #endif
> !
> ! #ifdef TCP_KEEPINTVL
> ! if (getsockopt(port->sock, SOL_TCP, TCP_KEEPINTVL,
> ! (char *) &port->default_keepalives_interval, &size) < 0)
> {
> ! elog(LOG, "getsockopt(TCP_KEEPINTVL) failed: %m");
> return STATUS_ERROR;
> }
> + #else
> + port->default_keepalives_idle = 0;
> + #endif
> +
> + #ifdef TCP_KEEPCNT
> + if (getsockopt(port->sock, SOL_TCP, TCP_KEEPCNT,
> + (char *) &port->default_keepalives_count, &size) < 0)
> + {
> + elog(LOG, "getsockopt(TCP_KEEPCNT) failed: %m");
> + return STATUS_ERROR;
> + }
> + #else
> + port->default_keepalives_idle = 0;
> + #endif
> +
> + /* Set default keepalive parameters. This should also catch
> + * misconfigurations (non-zero values when socket options aren't
> + * supported)
> + */
> + if (pq_setkeepalivesidle(tcp_keepalives_idle, port) != STATUS_OK)
> + return STATUS_ERROR;
> +
> + if (pq_setkeepalivesinterval(tcp_keepalives_interval, port) != STATUS_OK)
> + return STATUS_ERROR;
> +
> + if (pq_setkeepalivescount(tcp_keepalives_count, port) != STATUS_OK)
> + return STATUS_ERROR;
> }
>
> return STATUS_OK;
> ***************
> *** 1158,1160 ****
> --- 1204,1305 ----
> /* in non-error case, copy.c will have emitted the terminator line */
> DoingCopyOut = false;
> }
> +
> + int
> + pq_setkeepalives(bool onoff, Port *port)
> + {
> + int on = (onoff ? 1 : 0);
> +
> + if (IS_AF_UNIX(port->laddr.addr.ss_family))
> + return STATUS_OK;
> +
> + if (setsockopt(port->sock, SOL_SOCKET, SO_KEEPALIVE,
> + (char *) &on, sizeof(on)) < 0)
> + {
> + elog(LOG, "setsockopt(SO_KEEPALIVE) failed: %m");
> + return STATUS_ERROR;
> + }
> +
> + return STATUS_OK;
> + }
> +
> + int
> + pq_setkeepalivesidle(int idle, Port *port)
> + {
> + if (IS_AF_UNIX(port->laddr.addr.ss_family))
> + return STATUS_OK;
> +
> + #ifdef TCP_KEEPIDLE
> + if (idle == 0)
> + idle = port->default_keepalives_idle;
> +
> + if (setsockopt(port->sock, SOL_TCP, TCP_KEEPIDLE,
> + (char *) &idle, sizeof(idle)) < 0)
> + {
> + elog(LOG, "setsockopt(TCP_KEEPIDLE) failed: %m");
> + return STATUS_ERROR;
> + }
> + #else
> + if (idle != 0)
> + {
> + elog(LOG, "setsockopt(TCP_KEEPIDLE) not supported");
> + return STATUS_ERROR;
> + }
> + #endif
> +
> + return STATUS_OK;
> + }
> +
> + int
> + pq_setkeepalivesinterval(int interval, Port *port)
> + {
> + if (IS_AF_UNIX(port->laddr.addr.ss_family))
> + return STATUS_OK;
> +
> + #ifdef TCP_KEEPINTVL
> + if (interval == 0)
> + interval = port->default_keepalives_interval;
> +
> + if (setsockopt(port->sock, SOL_TCP, TCP_KEEPINTVL,
> + (char *) &interval, sizeof(interval)) < 0)
> + {
> + elog(LOG, "setsockopt(TCP_KEEPINTVL) failed: %m");
> + return STATUS_ERROR;
> + }
> + #else
> + if (interval != 0)
> + {
> + elog(LOG, "setsockopt(TCP_KEEPINTVL) not supported");
> + return STATUS_ERROR;
> + }
> + #endif
> +
> + return STATUS_OK;
> + }
> +
> + int
> + pq_setkeepalivescount(int count, Port *port)
> + {
> + if (IS_AF_UNIX(port->laddr.addr.ss_family))
> + return STATUS_OK;
> +
> + #ifdef TCP_KEEPCNT
> + if (count == 0)
> + count = port->default_keepalives_count;
> +
> + if (setsockopt(port->sock, SOL_TCP, TCP_KEEPCNT,
> + (char *) &count, sizeof(count)) < 0)
> + {
> + elog(LOG, "setsockopt(TCP_KEEPCNT) failed: %m");
> + return STATUS_ERROR;
> + }
> + #else
> + if (count != 0)
> + {
> + elog(LOG, "setsockopt(TCP_KEEPCNT) not supported");
> + return STATUS_ERROR;
> + }
> + #endif
> +
> + return STATUS_OK;
> + }
> Index: src/backend/utils/misc/guc.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql/src/backend/utils/misc/guc.c,v
> retrieving revision 1.261
> diff -c -r1.261 guc.c
> *** src/backend/utils/misc/guc.c 1 May 2005 18:56:19 -0000 1.261
> --- src/backend/utils/misc/guc.c 3 May 2005 01:44:08 -0000
> ***************
> *** 113,118 ****
> --- 113,125 ----
> static bool assign_transaction_read_only(bool newval, bool doit, GucSource source);
> static const char *assign_canonical_path(const char *newval, bool doit, GucSource source);
>
> + static bool assign_tcp_keepalives(bool newval, bool doit, GucSource source);
> + static bool assign_tcp_keepalives_idle(int newval, bool doit, GucSource source);
> + static bool assign_tcp_keepalives_interval(int newval, bool doit, GucSource source);
> + static bool assign_tcp_keepalives_count(int newval, bool doit, GucSource source);
> + static const char *show_tcp_keepalives_idle(void);
> + static const char *show_tcp_keepalives_interval(void);
> + static const char *show_tcp_keepalives_count(void);
>
> /*
> * GUC option variables that are exported from this module
> ***************
> *** 154,159 ****
> --- 161,170 ----
> char *IdentFileName;
> char *external_pid_file;
>
> + bool tcp_keepalives = true;
> + int tcp_keepalives_idle;
> + int tcp_keepalives_interval;
> + int tcp_keepalives_count;
>
> /*
> * These variables are all dummies that don't do anything, except in some
> ***************
> *** 860,865 ****
> --- 871,885 ----
> #endif
> },
>
> + {
> + {"tcp_keepalives", PGC_USERSET, CLIENT_CONN_OTHER,
> + gettext_noop("Use keepalives on client TCP connections."),
> + NULL,
> + },
> + &tcp_keepalives,
> + true, assign_tcp_keepalives, NULL
> + },
> +
> /* End-of-list marker */
> {
> {NULL, 0, 0, NULL, NULL}, NULL, false, NULL, NULL
> ***************
> *** 1333,1338 ****
> --- 1353,1387 ----
> BLCKSZ, BLCKSZ, BLCKSZ, NULL, NULL
> },
>
> + {
> + {"tcp_keepalives_idle", PGC_USERSET, CLIENT_CONN_OTHER,
> + gettext_noop("Seconds between issuing TCP keepalives."),
> + gettext_noop("A value of 0 uses the system default."),
> + },
> + &tcp_keepalives_idle,
> + 0, 0, INT_MAX, assign_tcp_keepalives_idle, show_tcp_keepalives_idle
> + },
> +
> + {
> + {"tcp_keepalives_interval", PGC_USERSET, CLIENT_CONN_OTHER,
> + gettext_noop("Seconds between TCP keepalive retransmits."),
> + gettext_noop("A value of 0 uses the system default."),
> + },
> + &tcp_keepalives_interval,
> + 0, 0, INT_MAX, assign_tcp_keepalives_interval, show_tcp_keepalives_interval
> + },
> +
> + {
> + {"tcp_keepalives_count", PGC_USERSET, CLIENT_CONN_OTHER,
> + gettext_noop("Maximum number of TCP keepalive retransmits."),
> + gettext_noop("This controls the number of consecutive keepalive retransmits that can be "
> + "lost before a connection is considered dead. A value of 0 uses the "
> + "system default."),
> + },
> + &tcp_keepalives_count,
> + 0, 0, INT_MAX, assign_tcp_keepalives_count, show_tcp_keepalives_count
> + },
> +
> /* End-of-list marker */
> {
> {NULL, 0, 0, NULL, NULL}, NULL, 0, 0, 0, NULL, NULL
> ***************
> *** 5677,5681 ****
> --- 5726,5802 ----
> return newval;
> }
>
> + static bool
> + assign_tcp_keepalives(bool newval, bool doit, GucSource source)
> + {
> + if (doit && MyProcPort != NULL)
> + {
> + pq_setkeepalives(newval, MyProcPort);
> + }
> + return true;
> + }
> +
> + static bool
> + assign_tcp_keepalives_idle(int newval, bool doit, GucSource source)
> + {
> + if (doit && MyProcPort != NULL)
> + {
> + return (pq_setkeepalivesidle(newval, MyProcPort) == STATUS_OK);
> + }
> +
> + return true;
> + }
> +
> + static const char *
> + show_tcp_keepalives_idle(void)
> + {
> + static char nbuf[32];
> + snprintf(nbuf, sizeof(nbuf), "%d",
> + (tcp_keepalives_idle != 0 || MyProcPort == NULL)
> + ? tcp_keepalives_idle : MyProcPort->default_keepalives_idle);
> + return nbuf;
> + }
> +
> + static bool
> + assign_tcp_keepalives_interval(int newval, bool doit, GucSource source)
> + {
> + if (doit && MyProcPort != NULL)
> + {
> + return (pq_setkeepalivesinterval(newval, MyProcPort) == STATUS_OK);
> + }
> +
> + return true;
> + }
> +
> + static const char *
> + show_tcp_keepalives_interval(void)
> + {
> + static char nbuf[32];
> + snprintf(nbuf, sizeof(nbuf), "%d",
> + (tcp_keepalives_interval != 0 || MyProcPort == NULL)
> + ? tcp_keepalives_interval : MyProcPort->default_keepalives_interval);
> + return nbuf;
> + }
> +
> + static bool
> + assign_tcp_keepalives_count(int newval, bool doit, GucSource source)
> + {
> + if (doit && MyProcPort != NULL)
> + {
> + return (pq_setkeepalivescount(newval, MyProcPort) == STATUS_OK);
> + }
> +
> + return true;
> + }
> +
> + static const char *
> + show_tcp_keepalives_count(void)
> + {
> + static char nbuf[32];
> + snprintf(nbuf, sizeof(nbuf), "%d",
> + (tcp_keepalives_count != 0 || MyProcPort == NULL)
> + ? tcp_keepalives_count : MyProcPort->default_keepalives_count);
> + return nbuf;
> + }
>
> #include "guc-file.c"
> Index: src/backend/utils/misc/postgresql.conf.sample
> ===================================================================
> RCS file: /projects/cvsroot/pgsql/src/backend/utils/misc/postgresql.conf.sample,v
> retrieving revision 1.140
> diff -c -r1.140 postgresql.conf.sample
> *** src/backend/utils/misc/postgresql.conf.sample 21 Apr 2005 19:18:13 -0000 1.140
> --- src/backend/utils/misc/postgresql.conf.sample 3 May 2005 01:44:08 -0000
> ***************
> *** 66,71 ****
> --- 66,77 ----
> #krb_server_keyfile = ''
> #db_user_namespace = false
>
> + # - TCP Keepalives -
> + # see 'man 7 tcp' for details
> + #tcp_keepalives = on # enables use of TCP keepalives
> + #tcp_keepalives_idle = 0 # TCP_KEEPIDLE, in seconds; 0 uses the system default.
> + #tcp_keepalives_interval = 0 # TCP_KEEPINTVL, in seconds; 0 uses the system default.
> + #tcp_keepalives_count = 0 # TCP_KEEPCNT, in seconds; 0 uses the system default.
>
> #---------------------------------------------------------------------------
> # RESOURCE USAGE (except WAL)
> Index: src/bin/psql/tab-complete.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql/src/bin/psql/tab-complete.c,v
> retrieving revision 1.125
> diff -c -r1.125 tab-complete.c
> *** src/bin/psql/tab-complete.c 21 Apr 2005 19:18:13 -0000 1.125
> --- src/bin/psql/tab-complete.c 3 May 2005 01:44:10 -0000
> ***************
> *** 595,600 ****
> --- 595,604 ----
> "superuser_reserved_connections",
> "syslog_facility",
> "syslog_ident",
> + "tcp_keepalives",
> + "tcp_keepalives_idle",
> + "tcp_keepalives_interval",
> + "tcp_keepalives_count",
> "temp_buffers",
> "TimeZone",
> "trace_notify",
> Index: src/include/libpq/libpq-be.h
> ===================================================================
> RCS file: /projects/cvsroot/pgsql/src/include/libpq/libpq-be.h,v
> retrieving revision 1.49
> diff -c -r1.49 libpq-be.h
> *** src/include/libpq/libpq-be.h 31 Dec 2004 22:03:32 -0000 1.49
> --- src/include/libpq/libpq-be.h 3 May 2005 01:44:10 -0000
> ***************
> *** 92,100 ****
> --- 92,113 ----
> char peer_cn[SM_USER + 1];
> unsigned long count;
> #endif
> +
> + /*
> + * Default TCP keepalive values found after accept(); 0 if unsupported or AF_UNIX.
> + */
> + int default_keepalives_idle;
> + int default_keepalives_interval;
> + int default_keepalives_count;
> } Port;
>
>
> extern ProtocolVersion FrontendProtocol;
>
> + /* TCP keepalives configuration. These are no-ops on an AF_UNIX socket. */
> + extern int pq_setkeepalives(bool onoff, Port *port);
> + extern int pq_setkeepalivesidle(int idle, Port *port);
> + extern int pq_setkeepalivesinterval(int interval, Port *port);
> + extern int pq_setkeepalivescount(int count, Port *port);
> +
> #endif /* LIBPQ_BE_H */
> Index: src/include/utils/guc.h
> ===================================================================
> RCS file: /projects/cvsroot/pgsql/src/include/utils/guc.h,v
> retrieving revision 1.60
> diff -c -r1.60 guc.h
> *** src/include/utils/guc.h 25 Mar 2005 16:17:28 -0000 1.60
> --- src/include/utils/guc.h 3 May 2005 01:44:10 -0000
> ***************
> *** 133,138 ****
> --- 133,142 ----
> extern char *IdentFileName;
> extern char *external_pid_file;
>
> + extern bool tcp_keepalives;
> + extern int tcp_keepalives_idle;
> + extern int tcp_keepalives_interval;
> + extern int tcp_keepalives_count;
>
> extern void SetConfigOption(const char *name, const char *value,
> GucContext context, GucSource source);

>
> ---------------------------(end of broadcast)---------------------------
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>
> http://www.postgresql.org/docs/faq

--
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