Static content deploy - Randomly css files not generated

[ihor-sviziev]

Preconditions (*)

1. Magento 2.3.x(2.3-develop too)
2. Configured Build system according to technical details.
3. Create own theme that extends from Magento/luma
4. Magento mode is default OR developer

Steps to reproduce (*)

1. Run php bin/magento setup:static-content:deploy -f -j $(nproc) (-j 8 in my case) with 6 different locales on build system

Expected result (*)

1. We should NOT have any errors/exceptions during SCD

Actual result (*)

1. Randomly we have following issue (sometimes from 4-5th time):

• Some CSS files are missing in pub/static directory
• Exception somewhere in the middle of SCD

This happening really randomly, sometimes with Magento/luma theme, sometimes with our own
File with errors:
errors.txt

Technical details

During SCD - it tries to compile LESS -> CSS files. During working on it - it tries to create lock, add some files and then unlock:

magento2/lib/internal/Magento/Framework/View/Asset/PreProcessor/AlternativeSource.php

Lines 108 to 116 in 15e3c07

	$this->lockerProcess->lockProcess($this->lockName);
	$module = $chain->getAsset()->getModule();
	/** @var FallbackContext $context */
	$context = $chain->getAsset()->getContext();
	$chain->setContent($this->processContent($path, $content, $module, $context));
	} finally {
	$this->lockerProcess->unlockProcess();

Details of these locks:

magento2/lib/internal/Magento/Framework/View/Asset/LockerProcess.php

Lines 63 to 77 in 15e3c07

	public function lockProcess($lockName)
	{
	if ($this->getState()->getMode() == State::MODE_PRODUCTION) {
	return;
	}
	$this->tmpDirectory = $this->filesystem->getDirectoryWrite(DirectoryList::VAR_DIR);
	$this->lockFilePath = $this->getFilePath($lockName);
	while ($this->isProcessLocked()) {
	usleep(1000);
	}
	$this->tmpDirectory->writeFile($this->lockFilePath, time());
	}

and

magento2/lib/internal/Magento/Framework/View/Asset/LockerProcess.php

Lines 83 to 90 in 15e3c07

	public function unlockProcess()
	{
	if ($this->getState()->getMode() == State::MODE_PRODUCTION) {
	return;
	}
	$this->tmpDirectory->delete($this->lockFilePath);
	}

As you can see above - locking process doesn't work in production mode, but static contend deploy we're running when env.php file is not present, so by fallback it runs in "default" magento mode.

Also that's not expected to have some lock when we're running SCD in parallel, it might significantly slow down this process.

This issue was discovered during testing #22607

[m2-assistant]

Hi @ihor-sviziev. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

• Summary of the issue
• Information on your environment
• Steps to reproduce
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Please make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, please, add a comment to the issue:

@magento-engcom-team give me 2.3-develop instance - upcoming 2.3.x release

For more details, please, review the Magento Contributor Assistant documentation.

@ihor-sviziev do you confirm that you were able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• yes
• no

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[m2-assistant]

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