Landscape Client

"change-packages" fails on PackageTask initialization

Bug #1994951 reported by Malte Kuhn
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Landscape Client
Fix Committed
Undecided
Unassigned

Bug Description

We have a standalone landscape server, that hands out a package "landscape-profile-standalone-company-tools".
On the server this activity is stuck in the "in progress" status.

On the client these logmessages can be found in syslog:

```
Oct 26 22:51:12 hostnamehere landscape-client[4159]: 2022-10-26 22:48:07,870 INFO [MainThread] Queueing message with updated reboot-required status.
Oct 26 22:51:12 hostnamehere landscape-client[4159]: 2022-10-26 22:48:07,871 INFO [MainThread] Queueing message with updated update-manager status.
Oct 26 22:51:12 hostnamehere landscape-client[4159]: 2022-10-26 22:48:07,871 ERROR [MainThread] Error running message handler for type 'change-packages': <bound method PackageManager.handle_change_packages of <landscape.client.manager.packagemanager.PackageManager object at 0x7f219d3d2500>>
Oct 26 22:51:12 hostnamehere landscape-client[4159]: Traceback (most recent call last):
Oct 26 22:51:12 hostnamehere landscape-client[4159]: File "/usr/lib/python3/dist-packages/landscape/client/broker/client.py", line 218, in dispatch_message
Oct 26 22:51:12 hostnamehere landscape-client[4159]: return handler(message)
Oct 26 22:51:12 hostnamehere landscape-client[4159]: File "/usr/lib/python3/dist-packages/landscape/client/manager/packagemanager.py", line 48, in handle_change_packages
Oct 26 22:51:12 hostnamehere landscape-client[4159]: return self._handle(PackageChanger, message)
Oct 26 22:51:12 hostnamehere landscape-client[4159]: File "/usr/lib/python3/dist-packages/landscape/client/manager/packagemanager.py", line 45, in _handle
Oct 26 22:51:12 hostnamehere landscape-client[4159]: self.spawn_handler(cls)
Oct 26 22:51:12 hostnamehere landscape-client[4159]: File "/usr/lib/python3/dist-packages/landscape/client/manager/packagemanager.py", line 71, in spawn_handler
Oct 26 22:51:12 hostnamehere landscape-client[4159]: if self._package_store.get_next_task(cls.queue_name):
Oct 26 22:51:12 hostnamehere landscape-client[4159]: File "/usr/lib/python3/dist-packages/landscape/lib/store.py", line 31, in inner
Oct 26 22:51:12 hostnamehere landscape-client[4159]: result = method(self, cursor, *args, **kwargs)
Oct 26 22:51:13 hostnamehere landscape-client[4159]: File "/usr/lib/python3/dist-packages/landscape/lib/apt/package/store.py", line 334, in get_next_task
Oct 26 22:51:13 hostnamehere landscape-client[4159]: return PackageTask(self._db, row[0])
Oct 26 22:51:13 hostnamehere landscape-client[4159]: File "/usr/lib/python3/dist-packages/landscape/lib/apt/package/store.py", line 435, in __init__
Oct 26 22:51:13 hostnamehere landscape-client[4159]: self.queue = row[0]
Oct 26 22:51:13 hostnamehere landscape-client[4159]: TypeError: 'NoneType' object is not subscriptable
Oct 26 22:51:13 hostnamehere landscape-client[4159]: 2022-10-26 22:48:37,859 INFO [MainThread] Ping indicates message available. Scheduling an urgent exchange.
```

Basically the PackageTask instance is unable to get the row that was found by get_next_task.

Additional information:
Landscape Client Version: 18.01-0ubuntu13
Operating System: Ubuntu 22.04.1 LTS
Kernel: Linux 5.15.0-52-generic
Architecture: x86-64
Hardware Vendor: Dell Inc.
Hardware Model: Latitude 5401
/ Filesystem is btrfs
I use suspend and hibernate via systemctl.

Workaround:
A restart of the landscape-client.service + cancel and redo on the activity resolves the matter as manual workaround.

See original description
Malte Kuhn (mc-mkuhn)
description: updated
Mitch Burton (mitchburton)
Changed in landscape-client:
status: New → In Progress
status: In Progress → Fix Committed
Revision history for this message
Juanmi Taboada (juanmitaboada) wrote :

The problem seems to be produced by a double SELECT:
- get_next_task() execute a SELECT which is valid and returns a valid ROW
- Then get_next_task() creates an instance from PackageTask, which executes a second SELECT to bring some fields from the database.

I must mention that get_next_task() is inside a transaction by the @with_cursor decorator, which shouldn't fail.

This solution optimizes the number of queries sent to the database and prevents this exception from happening.

A PR that removed the unnecessary SELECT has been proposed:
https://github.com/CanonicalLtd/landscape-client/pull/146

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