_import3 no longer blocks event loop during decryption

Now running encrytion of accounts in ProcessPoolExecutor

src/bot/message_handlers.py

@@ -1,6 +1,7 @@
 import asyncio
 import functools
 import gc
+import itertools
 from concurrent.futures import ProcessPoolExecutor
 
 import telebot
@@ -639,14 +640,26 @@ async def _import3(
     # List of names of accounts, which failed to be added to the database
     # or failed the tests
     failed: list[str] = []
-    for account in accounts:
-        if not check_account(account):
-            failed.append(account.name)
-            continue
-        account = encryption.accounts.encrypt(account, text)
-        result = db.add.add_account(engine, account)
-        if not result:
-            failed.append(account.name)
+    tasks: list[asyncio.Future[db.models.Account]] = []
+    loop = asyncio.get_running_loop()
+    with ProcessPoolExecutor() as pool:
+        for account in accounts:
+            if not check_account(account):
+                failed.append(account.name)
+                continue
+            function = functools.partial(
+                encryption.accounts.encrypt,
+                account,
+                text,
+            )
+            tasks.append(loop.run_in_executor(pool, function))
+        enc_accounts: list[db.models.Account] = await asyncio.gather(*tasks)
+    results = db.add.add_accounts(engine, enc_accounts)
+
+    failed_accounts = itertools.compress(
+        enc_accounts, (not result for result in results)
+    )
+    failed.extend((account.name for account in failed_accounts))
 
     if failed:
         await send_deleteable_message(
@@ -655,7 +668,7 @@ async def _import3(
     else:
         await send_tmp_message(bot, mes.chat.id, "Успех")
 
-    del text, mes, accounts
+    del text, mes, accounts, function, tasks, failed_accounts
     gc.collect()