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Bug
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Resolution: Fixed
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Major
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4.3.8, 4.4.4
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MOODLE_403_STABLE, MOODLE_404_STABLE
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MOODLE_404_STABLE, MOODLE_405_STABLE
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MDL-83079-404 -
MDL-83079-405 -
MDL-83079-main -
Setup environment for testing
- Setup redis
- Setup redis as the session handler (notice the session_redis_acquire_lock_timeout value):
$CFG->session_redis_host = '127.0.0.1';
$CFG->session_redis_port = 6379; // Optional.
$CFG->session_redis_acquire_lock_timeout = 5;
$CFG->session_handler_class = '\core\session\redis';
- Ensure you've install & enabled the "pcntl" php extension
- Make sure that the "pcntl_signal" function is not listed in the "disable_functions" setting located in your php.ini
- Create a test.php file in your moodle directory with the following contents:
<?phprequire_once __DIR__ . '/config.php';
// Kill current process with the SIGTERM signalposix_kill(posix_getpid(), 15);
Perform test
- Make a request to "https://{your_moodle_site}/test.php"
- Verify that you see the following page consistently after refreshing:
- Try to access any other page on the moodle site. Example: "https://{your_moodle_site}/login/index.php"
- Verify that you receive the expected page and don't get a "Cannot obtain session lock for sid: ..." exception
Setup environment for testing Setup redis Setup redis as the session handler (notice the session_redis_acquire_lock_timeout value): $CFG->session_redis_host = '127.0.0.1' ; $CFG->session_redis_port = 6379 ; // Optional. $CFG->session_redis_acquire_lock_timeout = 5 ; $CFG->session_handler_class = '\core\session\redis' ; Ensure you've install & enabled the "pcntl" php extension Make sure that the "pcntl_signal" function is not listed in the "disable_functions" setting located in your php.ini Create a test.php file in your moodle directory with the following contents: <?php require_once __DIR__ . '/config.php' ; // Kill current process with the SIGTERM signal posix_kill(posix_getpid(), 15); Perform test Make a request to "https://{your_moodle_site}/test.php" Verify that you see the following page consistently after refreshing: Try to access any other page on the moodle site. Example: "https://{your_moodle_site}/login/index.php" Verify that you receive the expected page and don't get a "Cannot obtain session lock for sid: ..." exception -
Code verified against automated checks. 
Checked
MDL-83079using repository: https://github.com/HuongNV13/moodle.git
MOODLE_404_STABLE (0 errors / 0 warnings) [branch: MDL-83079-404 | CI Job]- MOODLE_405_STABLE (0 errors / 0 warnings) [branch: MDL-83079-405 | CI Job]
- main (0 errors / 0 warnings) [branch: MDL-83079-main | CI Job]
More information about this report
Built on: Tue Jan 28 09:58:38 AM UTC 2025
Code verified against automated checks. Checked MDL-83079 using repository: https://github.com/HuongNV13/moodle.git MOODLE_404_STABLE (0 errors / 0 warnings) [branch: MDL-83079-404 | CI Job ] MOODLE_405_STABLE (0 errors / 0 warnings) [branch: MDL-83079-405 | CI Job ] main (0 errors / 0 warnings) [branch: MDL-83079-main | CI Job ] More information about this report Built on: Tue Jan 28 09:58:38 AM UTC 2025 -
If you send the SIGTERM signal to php-fpm, the shutdown handler is not called and the processes will just be killed.
This means any running requests will not release their session locks and will receive the "Cannot obtain session lock for sid: ..." error the next time they try to use the site.
When running your Moodle setup using kubernetes as an example, you send these signals to downscale the amount of pods. This causes users to receive a session lock preventing them from using their current session for the duration until it is automatically expired.
