multi: change sql db default max connections

invoices/kv_sql_migration_test.go

@@ -148,7 +148,7 @@ func TestMigrationWithChannelDB(t *testing.T) {
 			// Just some sane defaults for the sqlite config.
 			const (
 				timeout  = 5 * time.Second
-				maxConns = 50
+				maxConns = 2
 			)
 
 			sqliteConfig := &sqlite.Config{

kvdb/kvdb_sqlite.go

@@ -17,7 +17,10 @@ const (
 	// tag is defined. This will allow testing of other database backends.
 	SqliteBackend = true
 
-	testMaxConnections = 50
+	// Sqlite allows for concurrent reads however writers are limited to
+	// 1 so we select 2 here to allow for concurrent reads but keep the
+	// number of connections low to avoid write contention.
+	testMaxConnections = 2
 )
 
 // StartSqliteTestBackend starts a sqlite backed wallet.DB instance

kvdb/postgres/fixture.go

@@ -27,13 +27,18 @@ func getTestDsn(dbName string) string {
 
 var testPostgres *embeddedpostgres.EmbeddedPostgres
 
+// testMaxConnections is the total number of connections to the database server.
 const testMaxConnections = 200
 
+// testMaxConnectionPerDatabase is the number of connections per database the
+// golang driver will open.
+const testMaxConnectionPerDatabase = 10
+
 // StartEmbeddedPostgres starts an embedded postgres instance. This only needs
 // to be done once, because NewFixture will create random new databases on every
 // call. It returns a stop closure that stops the database if called.
 func StartEmbeddedPostgres() (func() error, error) {
-	sqlbase.Init(testMaxConnections)
+	sqlbase.Init(testMaxConnectionPerDatabase)
 
 	postgres := embeddedpostgres.NewDatabase(
 		embeddedpostgres.DefaultConfig().
@@ -43,6 +48,7 @@ func StartEmbeddedPostgres() (func() error, error) {
 					"max_connections": fmt.Sprintf(
 						"%d", testMaxConnections,
 					),
+					"max_pred_locks_per_transaction": "256",
 				},
 			),
 	)

lncfg/db.go

@@ -39,7 +39,7 @@ const (
 	SqliteBackend              = "sqlite"
 	DefaultBatchCommitInterval = 500 * time.Millisecond
 
-	defaultPostgresMaxConnections = 50
+	defaultPostgresMaxConnections = 10
 	defaultSqliteMaxConnections   = 2
 
 	defaultSqliteBusyTimeout = 5 * time.Second

sample-lnd.conf

@@ -1618,7 +1618,7 @@
 ; recommended to set a limit that is below the server connection limit.
 ; Otherwise errors may occur in lnd under high-load conditions.
 ; Default:
-;   db.postgres.maxconnections=50
+;   db.postgres.maxconnections=10
 ; Example:
 ;   db.postgres.maxconnections=
 

sqldb/config.go

@@ -7,12 +7,19 @@ import (
 )
 
 const (
-	// defaultMaxConns is the number of permitted active and idle
+	// defaultMaxConnsPostgres is the number of permitted active and idle
 	// connections. We want to limit this so it isn't unlimited. We use the
 	// same value for the number of idle connections as, this can speed up
 	// queries given a new connection doesn't need to be established each
 	// time.
-	defaultMaxConns = 25
+	defaultMaxConnsPostgres = 10
+
+	// defaultMaxConnsSqlite is the number of permitted active and idle
+	// connections. We want to limit this to 2 because SQLite allows for
+	// concurrent reads however writers are limited to 1 so we select 2 here
+	// to allow for concurrent reads but keep the number of connections low
+	// to avoid write contention.
+	defaultMaxConnsSqlite = 2
 
 	// connIdleLifetime is the amount of time a connection can be idle.
 	connIdleLifetime = 5 * time.Minute

sqldb/postgres.go

@@ -122,7 +122,7 @@ func NewPostgresStore(cfg *PostgresConfig) (*PostgresStore, error) {
 			err)
 	}
 
-	maxConns := defaultMaxConns
+	maxConns := defaultMaxConnsPostgres
 	if cfg.MaxConnections > 0 {
 		maxConns = cfg.MaxConnections
 	}

sqldb/postgres_fixture.go

@@ -60,6 +60,7 @@ func NewTestPgFixture(t testing.TB, expiry time.Duration) *TestPgFixture {
 			"-c", "log_statement=all",
 			"-c", "log_destination=stderr",
 			"-c", "max_connections=5000",
+			"-c", "max_pred_locks_per_transaction=256",
 		},
 	}, func(config *docker.HostConfig) {
 		// Set AutoRemove to true so that stopped container goes away

sqldb/sqlite.go

@@ -130,8 +130,13 @@ func NewSqliteStore(cfg *SqliteConfig, dbPath string) (*SqliteStore, error) {
 			err)
 	}
 
-	db.SetMaxOpenConns(defaultMaxConns)
-	db.SetMaxIdleConns(defaultMaxConns)
+	maxConns := defaultMaxConnsSqlite
+	if cfg.MaxConnections > 0 {
+		maxConns = cfg.MaxConnections
+	}
+
+	db.SetMaxOpenConns(maxConns)
+	db.SetMaxIdleConns(maxConns)
 	db.SetConnMaxLifetime(connIdleLifetime)
 	queries := sqlc.New(db)