don't flush active pack file that fast

we don't need to ensure all pack entries are written here, cuz all entries are new entries, and we will rollback all of them on failure

Author: Fallen-Breath

prime_backup/action/helpers/pack_writer.py

@@ -25,7 +25,6 @@ def append_reader(self, reader: SupportsReadBytes, size: int) -> PackEntryLocati
 				raise EOFError('reader exhausted with {} bytes remaining'.format(remaining))
 			self.file.write(buf)
 			remaining -= len(buf)
-		self.file.flush()
 
 		self.pack.size += size
 		self.pack.entry_count += 1
@@ -36,7 +35,6 @@ def append_reader(self, reader: SupportsReadBytes, size: int) -> PackEntryLocati
 
 	def append_bytes(self, data: bytes) -> PackEntryLocation:
 		self.file.write(data)
-		self.file.flush()
 
 		offset = self.pack.size
 		self.pack.size += len(data)
@@ -47,6 +45,7 @@ def append_bytes(self, data: bytes) -> PackEntryLocation:
 		return PackEntryLocation(self.pack.id, offset)
 
 	def close(self):
+		self.file.flush()
 		self.file.close()