Quote Attribute trigger_recollect causes a timeout

[bh-ref]

Preconditions

1. Magento CE 2.1.5
2. MariaDB 10.1.20
3. PHP 7.0.14

Steps to reproduce

0. We created a custom shipping carrier. This shipping carrier implements the method
   public function collectRates(RateRequest $request).
1. Log in as a customer.
2. Add some products to your quote.
3. Do not go to checkout. Log off.
4. Change some product and/or catalog price rules which affect the products in the quote from step 2. This should set the attribute trigger_recollect to 1 (integer) for that quote because of
   \Magento\Sales\Observer\Backend\CatalogProductSaveAfterObserver::execute() and
   \Magento\Sales\Observer\Backend\CatalogPriceRule::execute().
5. If you now log back in as a customer, your previous quote will be loaded.
6. If you then add a product, the shipping rate from our custom shipping carrier will be collected. We use \Magento\Checkout\Model\Cart::getQuote() to do some checks. \Magento\Quote\Model\Quote::_afterLoad() will eventually be triggered, which calls \Magento\Quote\Model\Quote::collectTotals() if the attribute trigger_recollect is set to 1.
7. Now, things begin to repeat because the rates for our custom shipping carrier are collected again.
8. A timeout appears because of this loop.
9. The customer cannot open any other page on the website, because this cycle continues for that customer. After waiting for the page to finish loading, all the customer will see in the end is a HTTP error 503.

Expected result

1. The attribute trigger_recollect in a quote should be set to 0 (integer) at some time.

Actual result

1. In all the magento code, I could only see the attribute trigger_recollect in a quote being set to 1, but never back to 0.

My patch, which seems to work fine, is:
In \Magento\Quote\Model\Quote::_afterLoad() add a reset of the attribute trigger_recollect after collecting the totals:

    protected function _afterLoad()
    {
        // collect totals and save me, if required
        if (1 == $this->getData('trigger_recollect')) {
            $this
                ->collectTotals()
                ->setTriggerRecollect(0) // patch: reset the attribute trigger_recollect
                ->save();
        }
        return parent::_afterLoad();
    }

[robbanl]

We have the EXACT same issue with Magento 2.1.4 that started a couple of days ago, probably due to a composer update! I'm about to try this fix right now!

[robbanl]

This solved our issue! Oh my god!

[robbanl]

@bh-ref Did you create module to fix this issue (I don't have any hopes that Magento will solve this within a year) or do you want me to create one?

[bh-ref]

@robbanl I'm glad it helped you!

Thanks for the offer, but we have a process were we directly patch the magento core files and note the github issues we open for these patches. If the patches are no longer applicable after a magento update, we either check if the problem was solved or update our github issues to let the magento team know that it still exists in the current version.
We also tried that approach of creating a module, but I think we could miss a fix because the plugin we would write would maybe work even after magento actually fixed the problem. So for us it is more a question of how you want to track if the bugs you discovered were fixed at some point...

[dankocherga]

This issue also causes problems with coupon codes:

1. Add 2 products to the shopping cart
2. Go to admin panel and disable one of the products
3. Try applying invalid coupon code in the shopping cart

Expected result: error message is displayed.
Actual result: success message is displayed.

Disabling a product sets a trigger_recollect flag to all quotes containing this product.
Then, when you try to apply a coupon code this happens:

1. Quote is loaded, and totals are collected in afterLoad, since trigger_recollect is set. This action also sets totals_collected_flag = true to avoid repeated collecting.
2. Coupon code is set to quote and Magento tries to collect totals, that should validate the coupon inside. But totals are already collected in afterLoad, so totals_collected_flag is set and collectTotals with coupon code does not happen.

[plastiqman]

We have the same problem in a Magento 2.1.9

We have detected 125 carts with this problem. But we have installed the MSP_CashOnDelivery.

Do you know if you have fixed this error in 2.1.9?

Thanks.

[magento-engcom-team]

@bh-ref, thank you for your report.
The issue is already fixed in 2.2.0