TYPO3 Core

I observed the same behaviour (CPU maxes out) in another installation.

The Locking method LOCKING_METHOD_SEMAPHORE simply is broken in 6.2.* and apparently also in the 6.2-compliancy code still living in 7.

Stefan's patch fixes the broken "while" perfect.

TYPO3\CMS\Frontend\Controller\TypoScriptFrontendController->acquirePageGenerationLock calls TYPO3\CMS\Core\Locking\Locker->acquire

I dug into that again and can explain that now.

The reason for FE still using the old acquire() method is that it relies on the (crazy) implementation of that function.
It is not feasible to replace the implementation in 6.2 anymore. I invested a fortune of time in 7 to get that whole API out of the way and the FE implementation correct.
For 6.2 I highly recommend to NOT use semaphore locking at all.
Some other reason: The implementation is not safe an uses different identifiers for the semaphores which causes the system to be flooded with semaphores. You need a root on the server to actually get rid of them. Number of semaphores allocated might be O(number of pages)

If it doesn't get fixed in 6.2 then you should at least disable the locking-mechanism semaphore in 6.2 with the next release if it's broken beyond repair.
It's an absurdity to speak of Long Term Support and then not fixing such inherently broken features.

I understand that:
- 6.2 LTS has a bug, which can bring down a webserver in seconds.
- The bug is well known, understood and can be fixed.
- The bug is also shipped with the 7.2 future LTS version (same code, same bug)

But "It is not feasible to replace the implementation in 6.2 anymore".
I fail to understand WHY.

Given Peter's Markus Klein's Warning:
"highly recommend to NOT use semaphore locking at all"
I suggest to:
- Change the LOCKING_METHOD_SEMAPHORE to use the filelocking Method (as is working)
- Remove the broken semaphore code.

Q: Shall we provide a patch implementing this strategy?

PS: Funny to read that the 6.2 Core uses a methode which is deprecated since 6.2, see:
TYPO3\CMS\Core\Locking\Locker->acquire
@deprecated since 6.2 - will be removed two versions later; use new API instead

Edit: "Peter" = MarkusK

- The bug is also shipped with the 7.2 future LTS version (same code, same bug)

No, because the API has been changed and this behaviour is therefore fixed!

It is not feasible to replace the implementation in 6.2 anymore

Because that is a fucking dangerous area in the most central component of FE.
For details on how to fix this, see details in
https://review.typo3.org/#/c/37700/20/typo3/sysext/frontend/Classes/Controller/TypoScriptFrontendController.php
and
https://review.typo3.org/#/c/38840/13/typo3/sysext/frontend/Classes/Controller/TypoScriptFrontendController.php

The recommendation stems from me and not from "Peter".

PS: Funny to read that the 6.2 Core uses a methode which is depre....

See my explanation above, why this is the case!

A: If you get that fixed, I'm happy to review a patch. But I can of course only speak for myself.

Markus, (!=Peter).
- Sorry for the name mismatch. Is corrected.

Thanks for your answer to my question:

Q: Shall we provide a patch implementing this strategy?
A: If you get that fixed, I'm happy to review a patch. But I can of course only speak for myself.

We'll work on that one.