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Detect POLLHUP/POLLRDHUP while running queries.

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Provide a new GUC check_client_connection_interval that can be used to
check whether the client connection has gone away, while running very
long queries.  It is disabled by default.

For now this uses a non-standard Linux extension (also adopted by at
least one other OS).  POLLRDHUP is not defined by POSIX, and other OSes
don't have a reliable way to know if a connection was closed without
actually trying to read or write.

In future we might consider trying to send a no-op/heartbeat message
instead, but that could require protocol changes.

Author: Sergey Cherkashin <s.cherkashin@postgrespro.ru>
Author: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: Tatsuo Ishii <ishii@sraoss.co.jp>
Reviewed-by: Konstantin Knizhnik <k.knizhnik@postgrespro.ru>
Reviewed-by: Zhihong Yu <zyu@yugabyte.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Maksim Milyutin <milyutinma@gmail.com>
Reviewed-by: Tsunakawa, Takayuki/綱川 貴之 <tsunakawa.takay@fujitsu.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> (much earlier version)
Discussion: https://postgr.es/m/77def86b27e41f0efcba411460e929ae%40postgrespro.ru
This commit is contained in:
Thomas Munro
2021-04-03 08:52:30 +13:00
parent 174edbe9f9
commit c30f54ad73
11 changed files with 156 additions and 0 deletions
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29
src/backend/utils/misc/guc.c
View File

@@ -20,6 +20,9 @@
#include <float.h>
#include <math.h>
#include <limits.h>
#ifdef HAVE_POLL_H
#include <poll.h>
#endif
#ifndef WIN32
#include <sys/mman.h>
#endif
@@ -204,6 +207,7 @@ static bool check_autovacuum_work_mem(int *newval, void **extra, GucSource sourc
static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source);
static bool check_maintenance_io_concurrency(int *newval, void **extra, GucSource source);
static bool check_huge_page_size(int *newval, void **extra, GucSource source);
static bool check_client_connection_check_interval(int *newval, void **extra, GucSource source);
static void assign_pgstat_temp_directory(const char *newval, void *extra);
static bool check_application_name(char **newval, void **extra, GucSource source);
static void assign_application_name(const char *newval, void *extra);
@@ -3501,6 +3505,17 @@ static struct config_int ConfigureNamesInt[] =
NULL, NULL, NULL
},
{
{"client_connection_check_interval", PGC_USERSET, CLIENT_CONN_OTHER,
gettext_noop("Sets the time interval between checks for disconnection while running queries."),
NULL,
GUC_UNIT_MS
},
&client_connection_check_interval,
0, 0, INT_MAX,
check_client_connection_check_interval, NULL, NULL
},
/* End-of-list marker */
{
{NULL, 0, 0, NULL, NULL}, NULL, 0, 0, 0, NULL, NULL, NULL
@@ -11980,6 +11995,20 @@ check_huge_page_size(int *newval, void **extra, GucSource source)
return true;
}
static bool
check_client_connection_check_interval(int *newval, void **extra, GucSource source)
{
#ifndef POLLRDHUP
/* Linux only, for now. See pq_check_connection(). */
if (*newval != 0)
{
GUC_check_errdetail("client_connection_check_interval must be set to 0 on platforms that lack POLLRDHUP.");
return false;
}
#endif
return true;
}
static void
assign_pgstat_temp_directory(const char *newval, void *extra)
{