Started to use db pool.

Cargo.lock

@@ -754,6 +754,8 @@ dependencies = [
  "log",
  "minijinja",
  "minijinja-autoreload",
+ "r2d2",
+ "r2d2_sqlite",
  "regex",
  "resource",
  "rusqlite",
@@ -1622,6 +1624,27 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "r2d2"
+version = "0.8.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51de85fb3fb6524929c8a2eb85e6b6d363de4e8c48f9e2c2eac4944abc181c93"
+dependencies = [
+ "log",
+ "parking_lot",
+ "scheduled-thread-pool",
+]
+
+[[package]]
+name = "r2d2_sqlite"
+version = "0.21.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4f5d0337e99cd5cacd91ffc326c6cc9d8078def459df560c4f9bf9ba4a51034"
+dependencies = [
+ "r2d2",
+ "rusqlite",
+]
+
 [[package]]
 name = "rand"
 version = "0.8.5"
@@ -1749,6 +1772,15 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "scheduled-thread-pool"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3cbc66816425a074528352f5789333ecff06ca41b36b0b0efdfbb29edc391a19"
+dependencies = [
+ "parking_lot",
+]
+
 [[package]]
 name = "scopeguard"
 version = "1.1.0"