[FIX] website: rollback transaction before creating new one

- When rendering a website page, exceptions might happens.
    If so, an error page is displayed, to do so we create
    a new psyscopg cursor to read the view in database and render it.

    But if the current (failed) transaction was holding a lock, the new
    cursor might have to wait for this lock to be released further
    down the line. However, this will only happen after the
    request is done (and in fact it won't happen). As a result, the
    current thread/worker is frozen until its timeout is reached.

    So rolling back the transaction will release any potential lock
    and, since we are in a case where an exception was raised, the
    transaction shouldn't be committed in the first place.

closes odoo/odoo#44085

X-original-commit: 7a61c89da5ccaed983275eb5f4986475ebf8b48d
Signed-off-by: Toufik Benjaa (tbe) <tbe@odoo.com>

addons/http_routing/models/ir_http.py

@@ -627,6 +627,21 @@ class IrHttp(models.AbstractModel):
 
         if not request.uid:
             cls._auth_method_public()
+
+        # We rollback the current transaction before initializing a new
+        # cursor to avoid potential deadlocks.
+
+        # If the current (failed) transaction was holding a lock, the new
+        # cursor might have to wait for this lock to be released further
+        # down the line. However, this will only happen after the
+        # request is done (and in fact it won't happen). As a result, the
+        # current thread/worker is frozen until its timeout is reached.
+
+        # So rolling back the transaction will release any potential lock
+        # and, since we are in a case where an exception was raised, the
+        # transaction shouldn't be committed in the first place.
+        request.env.cr.rollback()
+
         with registry(request.env.cr.dbname).cursor() as cr:
             env = api.Environment(cr, request.uid, request.env.context)
             if code == 500: