pgpool2.git / summary / log / commit / refs

commit    f2d5a3b815cece78eeef0163d262656b4562d443
Author:   Tatsuo Ishii <ishii@sraoss.co.jp>
Date:     Thu Apr 14 11:01:56 2022 +0000

    Fix exit_handler in pgpool main process.
    
    It was allowed to be interrupted by signals (SIGTERM, SIGINT and
    SOGQUIT) while the exit_handler. As a resit, exit_handler is executed
    while executing exit_handler. This could cause infinite wait in
    terminate_childrens() which is called from exit_handler.  To prevent
    this, protect variable "exiting" using semaphore to make sure that
    only one instance of exit_handler runs at the same time.
    
    Discussion: https://www.pgpool.net/pipermail/pgpool-hackers/2022-April/004149.html


 src/include/pool.h     |  3 ++-
 src/main/pgpool_main.c | 44 +++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/src/include/pool.h b/src/include/pool.h
index 1a892fc61..c8d97abfd 100644
--- a/src/include/pool.h
+++ b/src/include/pool.h
@@ -379,7 +379,7 @@ typedef enum
 #define Min(x, y)		((x) < (y) ? (x) : (y))
 
 
-#define MAX_NUM_SEMAPHORES		8
+#define MAX_NUM_SEMAPHORES		9
 #define CONN_COUNTER_SEM		0
 #define REQUEST_INFO_SEM		1
 #define SHM_CACHE_SEM			2
@@ -388,6 +388,7 @@ typedef enum
 #define ACCEPT_FD_SEM			5
 #define SI_CRITICAL_REGION_SEM	6
 #define FOLLOW_PRIMARY_SEM		7
+#define MAIN_EXIT_HANDLER_SEM	8	/* used in exit_hander in pgpool main process */
 #define MAX_REQUEST_QUEUE_SIZE	10
 
 #define MAX_SEC_WAIT_FOR_CLUSTER_TRANSACTION 10	/* time in seconds to keep
diff --git a/src/main/pgpool_main.c b/src/main/pgpool_main.c
index 861d9a27d..f0d362ac1 100644
--- a/src/main/pgpool_main.c
+++ b/src/main/pgpool_main.c
@@ -229,8 +229,8 @@ extern char *pcp_conf_file;		/* path for pcp.conf */
 extern char *conf_file;
 extern char *hba_file;
 
-static int	exiting = 0;		/* non 0 if I'm exiting */
-static int	switching = 0;		/* non 0 if I'm failing over or degenerating */
+static volatile sig_atomic_t exiting = 0;		/* non 0 if I'm exiting */
+static volatile sig_atomic_t switching = 0;		/* non 0 if I'm failing over or degenerating */
 
 POOL_REQUEST_INFO *Req_info;	/* request info area in shared memory */
 volatile sig_atomic_t *InRecovery;	/* non 0 if recovery is started */
@@ -1098,6 +1098,9 @@ terminate_all_childrens(int sig)
 }
 
 
+/*
+ * Pgpool main process exit handler
+ */
 static RETSIGTYPE exit_handler(int sig)
 {
 	int		   *walk;
@@ -1121,11 +1124,42 @@ static RETSIGTYPE exit_handler(int sig)
 		errno = save_errno;
 		return;
 	}
-	exiting = 1;
-	processState = EXITING;
 
+	/*
+	 * Check if another exit handler instance is already running.  It is
+	 * possible that exit_handler is interrupted in the middle by other
+	 * signal.
+	 */
+	if (exiting)
+	{
+		ereport(LOG,
+				(errmsg("exit handler (signal: %d) called. but exit handler is already in progress", sig)));
+		POOL_SETMASK(&UnBlockSig);
+		errno = save_errno;
+		return;
+	}
+
+	/* Check to make sure that other exit handler is not running */
+	pool_semaphore_lock(MAIN_EXIT_HANDLER_SEM);
+	if (exiting == 0)
+	{
+		exiting = 1;
+		pool_semaphore_unlock(MAIN_EXIT_HANDLER_SEM);
+	}
+	else
+	{
+		pool_semaphore_unlock(MAIN_EXIT_HANDLER_SEM);
+		ereport(LOG,
+				(errmsg("exit handler (signal: %d) called. but exit handler is already in progress", sig)));
+		POOL_SETMASK(&UnBlockSig);
+		errno = save_errno;
+		return;
+	}
+
+	processState = EXITING;
 	ereport(LOG,
-			(errmsg("shutting down")));
+			(errmsg("shutting down by signal %d", sig)));
+
 	/* Close listen socket if they are already initialized */
 	if (fds)
 	{


[parent: c13231cd2a08]