eldritch horrors
877b0d7121
we no longer use thread pools for querying missing derivations. this binds queryMissing to a single thread for now, but query performance is still greatly improved. we may want to optimize the store code in the near future too though since queryMissing is now fully cpu bound Change-Id: I08a9c8cc199963ef5981572ca4a32d90dbdec028
21 lines
1.0 KiB
Markdown
21 lines
1.0 KiB
Markdown
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synopsis: "Improved susbtituter query speed"
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issues: []
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cls: []
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category: Improvements
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credits: [horrors]
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---
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The code used to query substituters for derivations has been rewritten slightly
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to take advantage of our asynchronous runtime. Such queries run for every build
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that could download from substituters and processes every derivation that isn't
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yet present on the local system. Previously Lix would use `http-connections` to
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limit query concurrency, even for modern caches that support HTTP/2 and have no
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limit on how many queries can be run concurrently on one single connection. Lix
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no longer does this, resulting in approximately 60% reduction in query time for
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medium-sized closures (e.g. NixOS system closures) during testing, although the
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exact number depends greatly on local network latency and generally improves as
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latency increases. Unlike previously setting `http-connections` to `1` or other
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low values no longer brings a massive penalty in query performance if the cache
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in use by the querying system supports HTTP/2 (as e.g. `cache.nixos.org` does).
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