v9.0003.pgbench-barrier.patch

diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index 00c48b5afe..16a90a9fa3 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -292,6 +292,9 @@ typedef struct RandomState
 /* Various random sequences are initialized from this one. */
 static RandomState base_random_sequence;
 
+/* Synchronization barrier for start and connection */
+static pthread_barrier_t barrier;
+
 /*
  * Connection state machine states.
  */
@@ -435,8 +438,8 @@ typedef struct
 
 	/* per thread collected stats in microseconds */
 	pg_time_usec_t	create_time;	/* thread creation time */
-	pg_time_usec_t	started_time;	/* thread is running */
-	pg_time_usec_t	bench_start; 	/* thread is benchmarking */
+	pg_time_usec_t	started_time;	/* thread is running after start barrier */
+	pg_time_usec_t	bench_start; 	/* thread is benchmarking after connection barrier */
 	pg_time_usec_t	conn_duration;	/* cumulated connection and deconnection delays */
 
 	StatsData	stats;
@@ -6098,6 +6101,8 @@ main(int argc, char **argv)
 	if (duration > 0)
 		setalarm(duration);
 
+	pthread_barrier_init(&barrier, NULL, nthreads);
+
 #ifdef ENABLE_THREAD_SAFETY
 	/* start all threads but thread 0 which is executed directly later */
 	for (i = 1; i < nthreads; i++)
@@ -6169,6 +6174,8 @@ main(int argc, char **argv)
 	printResults(&stats, pg_time_now() - bench_start, conn_total_duration,
 				 bench_start - start_time, latency_late);
 
+	pthread_barrier_destroy(&barrier);
+
 	if (exit_code != 0)
 		pg_log_fatal("Run was aborted; the above results are incomplete.");
 
@@ -6215,6 +6222,8 @@ threadRun(void *arg)
 		state[i].state = CSTATE_CHOOSE_SCRIPT;
 
 	/* READY */
+	pthread_barrier_wait(&barrier);
+
 	thread_start = pg_time_now();
 	thread->started_time = thread_start;
 	last_report = thread_start;
@@ -6227,7 +6236,18 @@ threadRun(void *arg)
 		for (int i = 0; i < nstate; i++)
 		{
 			if ((state[i].con = doConnect()) == NULL)
+			{
+				/*
+				 * On connection failure, we meet the barrier here in place of
+				 * GO before proceeding to the "done" path which will cleanup,
+				 * so as to avoid locking the process.
+				 *
+				 * It is unclear whether it is worth doing anything rather than
+				 * coldly exiting with an error message.
+				 */
+				pthread_barrier_wait(&barrier);
 				goto done;
+			}
 		}
 
 		/* compute connection delay */
@@ -6239,6 +6259,8 @@ threadRun(void *arg)
 		thread->conn_duration = 0;
 	}
 
+	/* GO */
+	pthread_barrier_wait(&barrier);
 
 	start = pg_time_now();
 	thread->bench_start = start;