#23835: Infinite loop after squashing migrations
----------------------------+--------------------
Reporter: Twidi | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: master
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
----------------------------+--------------------
Take a "complex" dependency graph:
{{{
app_a: 0001 <-
\
app_b: 0001 <- x 0002 <-
/ \
app_c: 0001<- <------------- x 0002
}}}
And squash migrations on on '''app_c'''.
Now we should have a '''CircularDependencyError'''.
But we have an '''infinite loop'''.
Note that if "'''app_a'''" was named "'''app_d'''", the
'''CircularDependencyError''' would have been raised.
It's because of the "'''sorted'''" on the '''dfs''' function, in
'''django.db.migrations.graph'''.
Note that without this "'''sorted'''", the infinite loop could happen
randomely because we have a set. The problem is not here.
Condition to reproduce this bug: having a circular loop, and an node in
this loop having a dependency '''that has no dependency''', which will
reset the "'''path'''" list.
Indeed, if you remove the dependency of '''app_b.0002''' on '''app_a''',
the '''CircularDependencyError''' is raised.
You can see the test case here: https://github.com/twidi/django/compare
/squashing-infinite-loop
--
Ticket URL: <https://code.djangoproject.com/ticket/23835>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-updates/048.2967acc5488d9592235759b94fae3138%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.
