Catastrophic memory usage with lazy member variable
Originator: | colin.myr | ||
Number: | rdar://36412111 | Date Originated: | Jan 10th 2018 |
Status: | Open | Resolved: | |
Product: | macOS/Foundation | Product Version: | 10.12.6/9.2 |
Classification: | Bug | Reproducible: | Always |
Area: Foundation Summary: Modification of a member of a collection that is itself a lazy instance variable causes the collection to be copied. Steps to Reproduce: There is a sample Xcode project at https://github.com/cmyr/swift-lazy-perf Expected Results: Modification of the collection should be in-place. Actual Results: The collection is copied before each write. If the collection is not trivially small, frequent modifications significantly degrade application performance. Version/Build: Xcode Version 9.2 (9C40b) macOS 10.12.6 (16G1114)
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