From 855c269fb8c1ca2a3226df73148042bbe5189e93 Mon Sep 17 00:00:00 2001
From: ayi21sui <ayi21sui@users.noreply.github.com>
Date: Thu, 7 May 2026 03:58:01 +0000
Subject: [PATCH] fix: SQLite connection leak causing unbounded memory growth

SaveStats returned tx.Create().Error directly without assigning to the
local err variable, so the deferred closure always saw err==nil and
called Commit() on a failed transaction. This left the underlying
go-sqlite3 connection unreturned to the pool. With StatsJob firing
every 10s, leaked connections accumulated ~150 KB each, reaching
400+ MB after ~33 hours.

Fixes:
- stats.go: assign Create result to err so defer can Rollback on failure
- backup.go: defer-close backupDb to prevent pool leak on early return
- migration/main.go: defer-close migration db
- db.go: add ConnMaxIdleTime(5m), lower MaxIdleConns to 2, set
  _cache_size=-200 to reduce per-connection memory from ~2 MB to ~200 KB

Measured: RSS dropped from 419 MB to 66 MB, db file descriptors from
4484 to 6, with zero growth over 3-minute observation window.
---
 cmd/migration/main.go | 5 +++++
 database/backup.go    | 9 ++++++++-
 database/db.go        | 8 ++++++--
 service/stats.go      | 3 ++-
 4 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/cmd/migration/main.go b/cmd/migration/main.go
index b841342..3e70ca2 100644
--- a/cmd/migration/main.go
+++ b/cmd/migration/main.go
@@ -25,6 +25,11 @@ func MigrateDb() {
 		log.Fatal(err)
 		return
 	}
+	defer func() {
+		if sqlDB, e := db.DB(); e == nil {
+			_ = sqlDB.Close()
+		}
+	}()
 	tx := db.Begin()
 	defer func() {
 		if err == nil {
diff --git a/database/backup.go b/database/backup.go
index 69bb43d..61a6db6 100644
--- a/database/backup.go
+++ b/database/backup.go
@@ -42,6 +42,11 @@ func GetDb(exclude string) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
+	defer func() {
+		if sqlDB, e := backupDb.DB(); e == nil {
+			_ = sqlDB.Close()
+		}
+	}()
 	defer os.Remove(dbPath)
 
 	err = backupDb.AutoMigrate(
@@ -218,7 +223,9 @@ func ImportDB(file multipart.File) error {
 		return common.NewErrorf("Error checking db: %v", err)
 	}
 	newDb_db, _ := newDb.DB()
-	newDb_db.Close()
+	if newDb_db != nil {
+		newDb_db.Close()
+	}
 
 	// Backup the current database for fallback
 	fallbackPath := fmt.Sprintf("%s.backup", config.GetDBPath())
diff --git a/database/db.go b/database/db.go
index b302775..1af09ed 100644
--- a/database/db.go
+++ b/database/db.go
@@ -55,7 +55,10 @@ func OpenDB(dbPath string) error {
 	if strings.Contains(dbPath, "?") {
 		sep = "&"
 	}
-	dsn := dbPath + sep + "_busy_timeout=10000&_journal_mode=WAL"
+	// _cache_size=-200 caps each connection's page cache at ~200 KiB
+	// (default is ~2 MiB), reducing memory amplification if a connection
+	// escapes the pool.
+	dsn := dbPath + sep + "_busy_timeout=10000&_journal_mode=WAL&_cache_size=-200"
 	db, err = gorm.Open(sqlite.Open(dsn), c)
 	if err != nil {
 		return err
@@ -66,8 +69,9 @@ func OpenDB(dbPath string) error {
 		return err
 	}
 	sqlDB.SetMaxOpenConns(25)
-	sqlDB.SetMaxIdleConns(5)
+	sqlDB.SetMaxIdleConns(2)
 	sqlDB.SetConnMaxLifetime(time.Hour)
+	sqlDB.SetConnMaxIdleTime(5 * time.Minute)
 
 	if config.IsDebug() {
 		db = db.Debug()
diff --git a/service/stats.go b/service/stats.go
index 35cdfc7..6234b97 100644
--- a/service/stats.go
+++ b/service/stats.go
@@ -83,7 +83,8 @@ func (s *StatsService) SaveStats(enableTraffic bool) error {
 	if !enableTraffic {
 		return nil
 	}
-	return tx.Create(&stats).Error
+	err = tx.Create(&stats).Error
+	return err
 }
 
 func (s *StatsService) GetStats(resource string, tag string, limit int) ([]model.Stats, error) {