Adam Casey 04f1ead552 available_parallelism: Handle 0 cfs_period_us ... There seem to be some scenarios where `cpu.cfs_period_us` can contain `0` This causes a panic when calling `std:🧵:available_parallelism()` as is done so from binaries built by `cargo test`, which was how the issue was discovered. I don't feel like `0` is a good value for `cpu.cfs_period_us`, but I also don't think applications should panic if this value is seen. This case is handled by other projects which read this information: - num_cpus: e437b9d908/src/linux.rs (L207-L210) - ninja: https://github.com/ninja-build/ninja/pull/2174/files - dotnet: c4341d45ac/src/coreclr/pal/src/misc/cgroup.cpp (L481-L483) Before this change, this panic could be seen in environments setup as described above: ``` $ RUST_BACKTRACE=1 cargo test Finished test [unoptimized + debuginfo] target(s) in 3.55s Running unittests src/main.rs (target/debug/deps/x-9a42e145aca2934d) thread 'main' panicked at 'attempt to divide by zero', library/std/src/sys/unix/thread.rs:546:70 stack backtrace: 0: rust_begin_unwind 1: core::panicking::panic_fmt 2: core::panicking::panic 3: std::sys::unix:🧵:cgroups::quota 4: std::sys::unix:🧵:available_parallelism 5: std:🧵:available_parallelism 6: test::helpers::concurrency::get_concurrency 7: test::console::run_tests_console 8: test::test_main 9: test::test_main_static 10: x::main at ./src/main.rs:1:1 11: core::ops::function::FnOnce::call_once at /tmp/rust-1.64-1.64.0-1/library/core/src/ops/function.rs:248:5 note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace. error: test failed, to rerun pass '--bin local-rabmq-amqpprox' ``` I've tested this change in an environment which has the bad setup and rebuilding the test executable against a fixed std library fixes the panic.		2022-11-16 15:23:17 +00:00
..
benches	mv std libs to library/	2020-07-27 19:51:13 -05:00
primitive_docs	Add primitive documentation to libcore	2021-09-12 02:23:08 +00:00
src	available_parallelism: Handle 0 cfs_period_us	2022-11-16 15:23:17 +00:00
tests	Sort target features alphabetically	2022-10-14 22:01:18 +02:00
build.rs	Library changes for Apple WatchOS	2022-07-20 08:57:36 +01:00
Cargo.toml	Update compiler-builtins	2022-11-13 23:07:35 +05:30