Bug #40420
closed
Semaphore based locking returns warning
100%
Description
When using the 'semaphore' type locking functionality, sem_acquire return warning when identifier is released in another parallel request.
Example:
Core: Error handler (FE): PHP Warning: sem_acquire(): failed to acquire key 0x91b615ca: Identifier removed in /var/www/lib/typo3_src-4.6/t3lib/class.t3lib_lock.php line 211.
Is I understand it the flow is as following:
1. Request #1 is received.
2. sem_get is called with "id" as key
3. sem_acquire acquires semaphore with identifier from sem_get
4. Page generation begins
5. Request #2 is received
6. Request #2 sem_gets with "id" as key
7. Request #2 start loop on sem_acquire until it gets a lock
8. Request #1 completes, releases lock and removed identifier
9. Request #2 can't acquire, identifier is gone.
This could be considered similar to the unlink issue with the 'standard' locking method: http://forge.typo3.org/issues/32282 - the solution could be the same, adding a '@'...?
Files
Updated by Rudi Meyer about 12 years ago
- File class.t3lib_lock.php.patch class.t3lib_lock.php.patch added
- Target version set to 4.5.20
Here is my suggestion for a fix, I've gone with the same strategy as in http://forge.typo3.org/issues/32282, that is ignoring the warning. We know it will occur, we know why and we kinda don't care.
The patch is doable on both 4.5, 4.6 and 4.7 since no work has been done on 'class.t3lib_lock.php' in that time.
Updated by Markus Klein over 10 years ago
- Is Regression set to No
Hi Rudi!
This can only be solved cleanly by keeping a count on how many processes are currently having this semaphore.
The last one remaining has to remove the semaphore then.
This would of course require some shared memory or a file to store the number of processes. That takes time.
So my suggestion would be to NOT remove the the semaphore at all. Usually the same IDs are requested over and over again, so that shouldn't be a problem.
Although on heavy load this might cause issues with maximum resources available in the OS.
If that is the case, we've to implement shared memory.
What do you think?
Updated by Gerrit Code Review over 10 years ago
- Status changed from New to Under Review
Patch set 1 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 2 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 3 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 4 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 5 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 6 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 7 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 8 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 9 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 10 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 11 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 12 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 13 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 14 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 15 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 16 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 17 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Gerrit Code Review over 10 years ago
Patch set 18 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28159
Updated by Markus Klein over 10 years ago
- Status changed from Under Review to Resolved
- % Done changed from 0 to 100
Applied in changeset 34cc8f6c0253260abec1069e1c37611756b78e17.
Updated by Riccardo De Contardi about 7 years ago
- Status changed from Resolved to Closed