Drupal 7 to Drupal 11 migration runs forever

Ok, the reason for the infinite loop resides somewhere inside onPrepareRow() in /src/EventSubscriber/MediaMigrationSubscriber.php. Both running drush migrate-import --group=my_migration_group --continue-on-failure and drush migrate-upgrade --legacy-db-key=migrate --configure-only led to the infinite loop.

We tried deleting all migration ymls that were either provided or dependent on media_migration with no avail. After running the migration with minimal migration ymls in config the infinite loop still occured. Once we commented out the "onPrepareRow()" method call in the "MediaMigrationSubscriber" the migration started / the migration was configured successfully.

We will take a deeper look soon.

We found the issue!

This is caused by compatibility code for a core issue:

    // @todo remove when https://drupal.org/i/3164520 is fixed.
    $process = [
      [
        'plugin' => 'media_migration_delta_sort',
        'source' => $field_name,
      ],
    ];

https://drupal.org/i/3164520 was already merged in 9.x, so no idea, why it suddenly causes an infinite loop in 11.x, but nevertheless, this should be fixed.

Waiting for #3431903: Automated Drupal 11 compatibility fixes for media_migration to get fixed.

But this can already get reviewed.

Setting back to major, as the module isn't d11 compatible yet anyway.

EDIT: Although this might happen in d10 as well.

Bug is back on the table...

Ok for some reason, the added array_map changes from https://git.drupalcode.org/project/drupal/-/merge_requests/1797/diffs?fi... in core migrate results in this issue. If we revert getMigrationDependencies() to how it was in D9: https://git.drupalcode.org/project/drupal/-/blob/9.5.x/core/modules/migr... drush migrate-import --group=my_migration_group --continue-on-failure won't be stuck in an endless loop.

I have no idea, how this module affects that line of code. I already commented out all code inside MigratePluginAlterer and in the module file. But it is still stuck in that endless loop, unless I comment out this modules MediaMigrationSubscriber "onPrepareRow" method.

#3209706: Optimize SQL queries doesn't solve anything unfortunately.

Dirty core patch for the time being.

@Anybody and I will have a deeper look tomorrow.

Ok, to summarize this. The current MR has nothing to do with the problem and won't fix it.

I successfully migrated all the media to D11:

After applying "3494209-14.patch", I ran into #2797505: Migrations fail due to missing dependency when dependency has skipped rows by the source plugin, because with the patch applied, the dependencies seem to not get resolved correctly anymore. So I manually removed the failing dependencies. After that, a MigrateException was thrown in `/src/EventSubscriber/MediaMigrationSubscriber.php`, line 256.

I simply added a return statement above and everything worked as expected:

    if (empty($final_source_field_name[0]['field_name'])) {
      return;
      throw new MigrateException(
        sprintf(
          "Cannot identify the the media entity's source field name"
        )
      );
    }

This is quite dirty, but everything seems to got migrated just fine! Of course we should find the real cause of this endeavour.

OK, to quickly summarize my actions here:

NONE of the issue branches properly fix this problem!!!

I did a "successful" migration to D11 using the following patches:
Media Migration Patches:

• The D11 compatibility patch
• The dirty early return fix, avoiding an exception, which stops the migration

Drupal core Patches:

• This core patch to revert the array_map changes done in core

This is definitely not the proper way to do this, but it seems to do the job just fine. The real cause of this issue still needs to be found.

I've opened #3537372: Calling $migration->getMigrationDependencies() from a field plugin results in an infinate loop.