Always disable sync in SQLite cache

Author: ilevkivskyi

mypy/build.py

@@ -877,7 +877,7 @@ def __init__(
                 ]
             )
 
-        self.metastore = create_metastore(options, parallel_worker)
+        self.metastore = create_metastore(options)
 
         # a mapping from source files to their corresponding shadow files
         # for efficient lookup
@@ -1616,13 +1616,10 @@ def exclude_from_backups(target_dir: str) -> None:
         pass
 
 
-def create_metastore(options: Options, parallel_worker: bool = False) -> MetadataStore:
+def create_metastore(options: Options) -> MetadataStore:
     """Create the appropriate metadata store."""
     if options.sqlite_cache:
-        # We use this flag in both coordinator and workers to speed up commits,
-        # see mypy.metastore.connect_db() for details.
-        sync_off = options.num_workers > 0 or parallel_worker
-        mds: MetadataStore = SqliteMetadataStore(_cache_dir_prefix(options), sync_off=sync_off)
+        mds: MetadataStore = SqliteMetadataStore(_cache_dir_prefix(options))
     else:
         mds = FilesystemMetadataStore(_cache_dir_prefix(options))
     return mds

mypy/metastore.py

@@ -154,21 +154,20 @@ def close(self) -> None:
 """
 
 
-def connect_db(db_file: str, sync_off: bool = False) -> sqlite3.Connection:
+def connect_db(db_file: str) -> sqlite3.Connection:
     import sqlite3.dbapi2
 
     db = sqlite3.dbapi2.connect(db_file)
-    if sync_off:
-        # This is a bit unfortunate (as we may get corrupt cache after e.g. Ctrl + C),
-        # but without this flag, commits are *very* slow, especially when using HDDs,
-        # see https://www.sqlite.org/faq.html#q19 for details.
-        db.execute("PRAGMA synchronous=OFF")
+    # This is a bit unfortunate (as we may get corrupt cache after e.g. Ctrl + C),
+    # but without this flag, commits are *very* slow, especially when using HDDs,
+    # see https://www.sqlite.org/faq.html#q19 for details.
+    db.execute("PRAGMA synchronous=OFF")
     db.executescript(SCHEMA)
     return db
 
 
 class SqliteMetadataStore(MetadataStore):
-    def __init__(self, cache_dir_prefix: str, sync_off: bool = False) -> None:
+    def __init__(self, cache_dir_prefix: str) -> None:
         # We check startswith instead of equality because the version
         # will have already been appended by the time the cache dir is
         # passed here.
@@ -177,7 +176,7 @@ def __init__(self, cache_dir_prefix: str, sync_off: bool = False) -> None:
             return
 
         os.makedirs(cache_dir_prefix, exist_ok=True)
-        self.db = connect_db(os_path_join(cache_dir_prefix, "cache.db"), sync_off=sync_off)
+        self.db = connect_db(os_path_join(cache_dir_prefix, "cache.db"))
 
     def _query(self, name: str, field: str) -> Any:
         # Raises FileNotFound for consistency with the file system version