Uploaded image for project: 'Moodle'
  1. Moodle
  2. MDL-43421

user_lastaccess race condition

    XMLWordPrintable

Details

    • MOODLE_25_STABLE, MOODLE_27_STABLE, MOODLE_28_STABLE, MOODLE_29_STABLE
    • MOODLE_27_STABLE, MOODLE_28_STABLE
    • Hide

      The only way I found to test the race condition was to manually insert a sleep of 60 seconds into the before the insert_record_raw call just after lib/datalib.php:1700.

      So to test the race condition;
      1. Insert the sleep(60) in lib/datalib.php just before insert_record_raw
      2. Open browser as an admin.
      3. Create a new user.
      4. Enrol that user in a course, existing or new.
      5. Logout as admin
      6. Open two browsers and login as the newly created user.
      7. In EACH of the browsers, click on the course they are enrolled in.
      8. Confirm both pages load without logging an exception.
      9. Verify the last access time is correct.

      Show
      The only way I found to test the race condition was to manually insert a sleep of 60 seconds into the before the insert_record_raw call just after lib/datalib.php:1700. So to test the race condition; 1. Insert the sleep(60) in lib/datalib.php just before insert_record_raw 2. Open browser as an admin. 3. Create a new user. 4. Enrol that user in a course, existing or new. 5. Logout as admin 6. Open two browsers and login as the newly created user. 7. In EACH of the browsers, click on the course they are enrolled in. 8. Confirm both pages load without logging an exception. 9. Verify the last access time is correct.

    Description

      There is a race condition in user_lastaccess updates. Two insert attempts can be made at the one time. This is not usually an issue as a single user is not operating on the same course at the same time when it's not been accessed before.

      However with webservices, it's possible to have two calls to a new course and they bump into each other.

      Attachments

        Issue Links

          has a non-specific relationship to

          Bug - A problem which impairs or prevents Moodle from functioning correctly. MDLSITE-1915 Moodle.org availability problems - September 2012

          • High - Customer/Partner Issue, GDPR removal, priority Features
          • Closed

          Bug - A problem which impairs or prevents Moodle from functioning correctly. MDL-35257 Guess last access record is being updated when autologged in.. can lead to contention

          • Minor - Minor loss of function where workaround is possible
          • Closed
          is a regression caused by

          Sub-task - Issues are sometimes broken into multiple sub-tasks. MDL-18293 do not check return value from isert_record and update_record and cleanup unused error messages replaced by new DML exceptions

          • Minor - Minor loss of function where workaround is possible
          • Closed
          will be (partly) resolved by

          Task - A task that needs to be completed. Tasks usually refer to work that must be done outside the product. MDL-46064 Drop support for MyISAM for 2.9

          • Critical - Crashes server, loss of data, severe memory leak
          • Closed

          Activity

            People

              mr-russ Russell Smith
              mr-russ Russell Smith
              Dan Poltawski Dan Poltawski
              Eloy Lafuente (stronk7) Eloy Lafuente (stronk7)
              Ankit Agarwal Ankit Agarwal
              Andrew Lyons, Huong Nguyen, Jun Pataleta, Michael Hawkins, Shamim Rezaie, Simey Lameze, Stevani Andolo, Juan Leyva, Amaia Anabitarte, Carlos Escobedo, Ferran Recio, Ilya Tregubov, Laurent David, Raquel Ortega, Sara Arjona (@sarjona)
              Votes:
              0 Vote for this issue
              Watchers:
              7 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved:
                2/Feb/15