Improve jest-worker (up to 4x)#5793
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@@ Coverage Diff @@
## master #5793 +/- ##
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- Coverage 63.74% 63.73% -0.01%
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Files 216 216
Lines 7929 7938 +9
Branches 4 3 -1
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+ Hits 5054 5059 +5
- Misses 2874 2878 +4
Partials 1 1
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cpojer
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Mar 14, 2018
| _options: WorkerOptions; | ||
| _queue: Array<QueueChildMessage>; | ||
| _queue: ?QueueChildMessage; | ||
| _last: ?QueueChildMessage; |
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this is not in the right alphabetical location :P
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This is really fantastic. Thanks @mjesun, great work! |
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Beauty!! |
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This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs. |
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This PR modifies the way internal worker queues are managed, passing from an array to a linked-list, improving a 10% the current benchmark, and 400% over a new benchmark.
How come this wasn't noticed before?
When
jest-workerwas initially benchmarked, it was done by using not so many jobs (~10k), but very heavy in time. While this is the usual approach (few jobs, lots of time per job), sometimes you have the opposite (i.e. lots of jobs, but each of them very fast). This is actually whatjest-haste-mapdoes.Since the internal queue was an array, re-indexing the queue is a
O(n)operation, which becomes especially relevant on the second scenario. Switching to a linked list means that all operations for advancing the queue becomeO(1), no matter its length. This results in massive speed improvements on really long queues.Some benchmarks
Using the extended performance test, the
emptyfunction, called 100,000 times results in:Now, with the change, it results in:
What about the existing metrics?
The previous metric (which we initially used for benchmarking,
loadTestcalled 10,000 times), has also improved, but only slightly, since that one was already optimized:Tests
I ensured all tests pass, but I also added some slight modifications into the
__performance__tests__so that you can pass an arbitrary worker method as well as an arbitrary number of iterations. This allowed me to test the other scenario.On a personal note: this is actually WHY algorithms and data structures knowledge IS important for a frontend developer! 🙂