Reduce macOS LLVM build parallelism to avoid compiler segfaults#5100
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SeanTAllen merged 1 commit intomainfrom Apr 2, 2026
Merged
Reduce macOS LLVM build parallelism to avoid compiler segfaults#5100SeanTAllen merged 1 commit intomainfrom
SeanTAllen merged 1 commit intomainfrom
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Apple Clang on the macos-26 runners has been segfaulting during LLVM builds, likely due to memory pressure from too many parallel compilation jobs. Intel runners have 4 cores and ARM64 runners have 10 cores, so -j8 was particularly aggressive for Intel. Reduce to -j2 for Intel and -j4 for ARM64.
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This is a pure shot in the dark but we keep dying and failing and segfaulting the last couple days building LLVM on macos runners. We have other failures as well running the stress tests that are "vm went away" so this might not be a valid fix or it might be that something changed with runners and it is causing multiple problems. |
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Apple Clang on the macos-26 runners has been segfaulting during LLVM lib builds (
Segmentation fault: 11inclang++), causing repeated CI failures on both Intel and ARM64 macOS jobs starting around April 1.The Intel runners only have 4 cores, so
-j8was double the core count and likely causing memory pressure. ARM64 runners have 10 cores but the LLVM translation units being compiled are very memory-heavy.This reduces parallelism to
-j2for Intel (macos-26-intel) and-j4for ARM64 (macos-26). Linux and Docker jobs remain at-j8.