concurrent access to luarocks cache trigger "Failed loading manifest for https://luarocks.org: Error loading file" about luarocks HOT 4 CLOSED

LuaRocks does not support concurrent updates. The best we could would be to add some global locking, if lfs can do that...

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@teto I added some locking -- the lock for the cache is a try-lock which creates a temporary cache dir if it can't acquire it, but the repositories have a lock which fails the command if another one is in progress.

This means that if you are building with different --tree targets, things should work. If you are targeting the same tree, you'll get safer failures. Exit code 4 means a lock failure, meaning you can wait and retry later.

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is there any trick I could leverage like :

• pass the manifest myself
• set its lifetime to a high value so that luarocks doesn't try to redownload it itself ?
• prefetch it and make it read-only ?

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If you're doing concurrent builds targeting the same trees, I'm afraid not. If you do that you are probably going to get other clashes when instances scan the filesystem for generating the local manifests as packages get installed.

HOWEVER, if you're targeting independent trees and the only clashes you are getting are from the LuaRocks cache, then you have a solution: get each instance to use a separate config file (which you can supply the luarocks process with the LUAROCKS_CONFIG environment variable) with a different folder in the local_cache setting. (There's currently no way to pass individual config settings to a luarocks command, so you'll need the one-config-file-per-instance kludge...)

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