move drop(db) to the end

src/main.rs

@@ -106,7 +106,6 @@ fn main() {
             }
         });
         pre_tx.commit().unwrap();
-        drop(pre_tx);
         drop(db);
         // re-open db
         saved.tmp_store = true;
@@ -177,9 +176,6 @@ fn main() {
     for x in h {
         x.join().unwrap();
     }
-    drop(db);
-    #[cfg(feature = "custom_alloc")]
-    print_filtered_trace(|x, y| log::info!("{}{}", x, y));
 
     let test_start = start_time.lock().unwrap();
     let duration = test_start.elapsed();
@@ -214,4 +210,7 @@ fn main() {
         ops,
         duration.as_millis()
     );
+    drop(db);
+    #[cfg(feature = "custom_alloc")]
+    print_filtered_trace(|x, y| log::info!("{}{}", x, y));
 }