From: Yugo Nagata <nagata@sraoss.co.jp>
Date: Wed, 15 Jun 2016 06:24:21 +0000 (+0900)
Subject: Fix a posible hang during health checking
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=refs%2Fheads%2FV3_1_STABLE;p=pgpool2.git

Fix a posible hang during health checking

Helath checking was hang when any data wasn't sent
from backend after connect(2) succeeded. To fix this,
pool_check_fd() returns 1 when select(2) exits with
EINTR due to SIGALRM while health checkking is performed.

Reported and patch provided by harukat and some modification
by Yugo. Per bug #204.

backported from 3.4 or later;
https://git.postgresql.org/gitweb/?p=pgpool2.git;a=commitdiff;h=ed9f2900f1b611f5cfd52e8f758c3616861e60c0
---

diff --git a/main.c b/main.c
index a32afaec2..f7de0ac2c 100644
--- a/main.c
+++ b/main.c
@@ -162,7 +162,7 @@ static int not_detach = 0;		/* non 0 if non detach option (-n) is given */
 
 static int stop_sig = SIGTERM;	/* stopping signal default value */
 
-static volatile sig_atomic_t health_check_timer_expired;		/* non 0 if health check timer expired */
+volatile sig_atomic_t health_check_timer_expired;               /* non 0 if health check timer expired */
 
 POOL_REQUEST_INFO *Req_info;		/* request info area in shared memory */
 volatile sig_atomic_t *InRecovery; /* non 0 if recovery is started */
diff --git a/pool.h b/pool.h
index 8107b5c55..c3fb39bdb 100644
--- a/pool.h
+++ b/pool.h
@@ -397,6 +397,7 @@ extern bool run_as_pcp_child;
 
 extern POOL_CONNECTION_POOL *pool_connection_pool;	/* connection pool */
 extern volatile sig_atomic_t backend_timer_expired; /* flag for connection closed timer is expired */
+extern volatile sig_atomic_t health_check_timer_expired;		/* non 0 if health check timer expired */
 extern long int weight_master;	/* normalized weight of master (0-RAND_MAX range) */
 extern int my_proc_id;  /* process table id (!= UNIX's PID) */
 extern POOL_SYSTEMDB_CONNECTION_POOL *system_db_info; /* systemdb */
diff --git a/pool_process_query.c b/pool_process_query.c
index fd815b998..27fbc4d55 100644
--- a/pool_process_query.c
+++ b/pool_process_query.c
@@ -1054,6 +1054,7 @@ int pool_check_fd(POOL_CONNECTION *cp)
 	int fds;
 	struct timeval timeout;
 	struct timeval *timeoutp;
+	int save_errno;
 
 	/*
 	 * If SSL is enabled, we need to check SSL internal buffer
@@ -1083,8 +1084,15 @@ int pool_check_fd(POOL_CONNECTION *cp)
 		FD_SET(fd, &exceptmask);
 
 		fds = select(fd+1, &readmask, NULL, &exceptmask, timeoutp);
+		save_errno = errno;
 		if (fds == -1)
 		{
+			if (health_check_timer_expired && errno == EINTR)
+			{
+				pool_error("health check timed out while waiting for reading data");
+				errno = save_errno;
+				return 1;
+			}
 			if (errno == EAGAIN || errno == EINTR)
 				continue;