зеркало из https://github.com/mozilla/gecko-dev.git
b547239226
ff5a4bab0813 (bug 1311791) and 332a08725ed0 (bug 1292071) changed behavior of the VCS caches. First, the store cache / path was merged into the checkouts cache. Then the path of the Mercurial shared store was moved within the cache to always be rooted at the cache root. Caches are shared across tasks. Tasks can execute on any revision configured to use a cache. So, when interacting with caches, it is important to consider how every revision configured to use that cache will interact with it. Take this scenario for example. A worker executes a task where the hg shared store is rooted at /home/worker/checkouts/src/hg-shared. Then the worker executes a task where the hg shared store is rooted at /home/worker/checkouts/hg-store. `hg robustcheckout` will see the checkout from the first task. But then it sees that the store it is pointing to is at an unexpected location (checkouts/src/hg-shared instead of checkouts/hg-store). `hg robustcheckout` aggressively normalizes state to ensure consistency. So when it sees this mismatch, it blows away the checkout and creates one from checkouts/hg-store to replace it. That's a lot of overhead. And this cycle can repeat itself if the right combination of revisions run on the worker! A solution to this problem is to create a clean break from caches when cache semantics change. In TaskCluster, that means using a different cache. This commit introduces a "version" component to the checkouts cache name. By doing so, we create a clean break from all previous caches, ensuring all revisions this point forward won't encounter an hg shared store at an unexpected location. This also paves the road for easily making additional clean breaks in the future. MozReview-Commit-ID: JT8yuULKpch --HG-- extra : rebase_source : 2e5d321e4314ff7543423d3c7837b770b7c8a3a3 |
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| .. | ||
| attributes.rst | ||
| caches.rst | ||
| docker-images.rst | ||
| how-tos.rst | ||
| index.rst | ||
| kinds.rst | ||
| loading.rst | ||
| parameters.rst | ||
| reference.rst | ||
| taskgraph.rst | ||
| transforms.rst | ||
| yaml-templates.rst | ||