Fix cases where net conn write failure was not marking connection as dead

Also added loop to run these timing sensitive tests multiple times.

conn.go

@@ -483,6 +483,7 @@ func (c *Conn) Prepare(name, sql string) (ps *PreparedStatement, err error) {
 
 	_, err = c.conn.Write(wbuf.buf)
 	if err != nil {
+		c.die(err)
 		return nil, err
 	}
 
@@ -544,6 +545,7 @@ func (c *Conn) Deallocate(name string) (err error) {
 
 	_, err = c.conn.Write(wbuf.buf)
 	if err != nil {
+		c.die(err)
 		return err
 	}
 

conn_pool_test.go

@@ -229,64 +229,69 @@ func TestPoolAcquireAndReleaseCycleAutoConnect(t *testing.T) {
 func TestPoolReleaseDiscardsDeadConnections(t *testing.T) {
 	t.Parallel()
 
-	maxConnections := 3
-	pool := createConnPool(t, maxConnections)
-	defer pool.Close()
+	// Run timing sensitive test many times
+	for i := 0; i < 50; i++ {
+		func() {
+			maxConnections := 3
+			pool := createConnPool(t, maxConnections)
+			defer pool.Close()
 
-	var c1, c2 *pgx.Conn
-	var err error
-	var stat pgx.ConnPoolStat
+			var c1, c2 *pgx.Conn
+			var err error
+			var stat pgx.ConnPoolStat
+
+			if c1, err = pool.Acquire(); err != nil {
+				t.Fatalf("Unexpected error acquiring connection: %v", err)
+			}
+			defer func() {
+				if c1 != nil {
+					pool.Release(c1)
+				}
+			}()
+
+			if c2, err = pool.Acquire(); err != nil {
+				t.Fatalf("Unexpected error acquiring connection: %v", err)
+			}
+			defer func() {
+				if c2 != nil {
+					pool.Release(c2)
+				}
+			}()
+
+			if _, err = c2.Exec("select pg_terminate_backend($1)", c1.Pid); err != nil {
+				t.Fatalf("Unable to kill backend PostgreSQL process: %v", err)
+			}
+
+			// do something with the connection so it knows it's dead
+			rows, _ := c1.Query("select 1")
+			rows.Close()
+			if rows.Err() == nil {
+				t.Fatal("Expected error but none occurred")
+			}
+
+			if c1.IsAlive() {
+				t.Fatal("Expected connection to be dead but it wasn't")
+			}
+
+			stat = pool.Stat()
+			if stat.CurrentConnections != 2 {
+				t.Fatalf("Unexpected CurrentConnections: %v", stat.CurrentConnections)
+			}
+			if stat.AvailableConnections != 0 {
+				t.Fatalf("Unexpected AvailableConnections: %v", stat.CurrentConnections)
+			}
 
-	if c1, err = pool.Acquire(); err != nil {
-		t.Fatalf("Unexpected error acquiring connection: %v", err)
-	}
-	defer func() {
-		if c1 != nil {
 			pool.Release(c1)
-		}
-	}()
+			c1 = nil // so it doesn't get released again by the defer
 
-	if c2, err = pool.Acquire(); err != nil {
-		t.Fatalf("Unexpected error acquiring connection: %v", err)
-	}
-	defer func() {
-		if c2 != nil {
-			pool.Release(c2)
-		}
-	}()
-
-	if _, err = c2.Exec("select pg_terminate_backend($1)", c1.Pid); err != nil {
-		t.Fatalf("Unable to kill backend PostgreSQL process: %v", err)
-	}
-
-	// do something with the connection so it knows it's dead
-	rows, _ := c1.Query("select 1")
-	rows.Close()
-	if rows.Err() == nil {
-		t.Fatal("Expected error but none occurred")
-	}
-
-	if c1.IsAlive() {
-		t.Fatal("Expected connection to be dead but it wasn't")
-	}
-
-	stat = pool.Stat()
-	if stat.CurrentConnections != 2 {
-		t.Fatalf("Unexpected CurrentConnections: %v", stat.CurrentConnections)
-	}
-	if stat.AvailableConnections != 0 {
-		t.Fatalf("Unexpected AvailableConnections: %v", stat.CurrentConnections)
-	}
-
-	pool.Release(c1)
-	c1 = nil // so it doesn't get released again by the defer
-
-	stat = pool.Stat()
-	if stat.CurrentConnections != 1 {
-		t.Fatalf("Unexpected CurrentConnections: %v", stat.CurrentConnections)
-	}
-	if stat.AvailableConnections != 0 {
-		t.Fatalf("Unexpected AvailableConnections: %v", stat.CurrentConnections)
+			stat = pool.Stat()
+			if stat.CurrentConnections != 1 {
+				t.Fatalf("Unexpected CurrentConnections: %v", stat.CurrentConnections)
+			}
+			if stat.AvailableConnections != 0 {
+				t.Fatalf("Unexpected AvailableConnections: %v", stat.CurrentConnections)
+			}
+		}()
 	}
 }
 

conn_test.go

@@ -945,27 +945,32 @@ func TestFatalRxError(t *testing.T) {
 func TestFatalTxError(t *testing.T) {
 	t.Parallel()
 
-	conn := mustConnect(t, *defaultConnConfig)
-	defer closeConn(t, conn)
+	// Run timing sensitive test many times
+	for i := 0; i < 50; i++ {
+		func() {
+			conn := mustConnect(t, *defaultConnConfig)
+			defer closeConn(t, conn)
 
-	otherConn, err := pgx.Connect(*defaultConnConfig)
-	if err != nil {
-		t.Fatalf("Unable to establish connection: %v", err)
-	}
-	defer otherConn.Close()
+			otherConn, err := pgx.Connect(*defaultConnConfig)
+			if err != nil {
+				t.Fatalf("Unable to establish connection: %v", err)
+			}
+			defer otherConn.Close()
 
-	_, err = otherConn.Exec("select pg_terminate_backend($1)", conn.Pid)
-	if err != nil {
-		t.Fatalf("Unable to kill backend PostgreSQL process: %v", err)
-	}
+			_, err = otherConn.Exec("select pg_terminate_backend($1)", conn.Pid)
+			if err != nil {
+				t.Fatalf("Unable to kill backend PostgreSQL process: %v", err)
+			}
 
-	_, err = conn.Query("select 1")
-	if err == nil {
-		t.Fatal("Expected error but none occurred")
-	}
+			_, err = conn.Query("select 1")
+			if err == nil {
+				t.Fatal("Expected error but none occurred")
+			}
 
-	if conn.IsAlive() {
-		t.Fatal("Connection should not be live but was")
+			if conn.IsAlive() {
+				t.Fatalf("Connection should not be live but was. Previous Query err: %v", err)
+			}
+		}()
 	}
 }