Terminating the process with `panic` takes longer with `panic="abort"`?

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1

In my debug builds panic terminates the process right away, it takes no time.

In release builds panic takes a second or two before the process termintes.

Normally who cares, but I have a weird test setup where I run my executable on about a hundred files. Most of them panic today.

As I fix the tests there will be no panics, but today running this test suite spends maybe half a minute on these post-panic delays.

I investigated this issue a little bit and it turns out it's this line in my Cargo.toml that causes the issue:

[profile.release]
panic = "abort"

With the default panic setting (unwind?) the processes terminate fast.

Is this expected? How can aborting the process take longer than aborting right away on panic?

2

How are you measuring this? Can you show your repro steps?

3

Repro:

  • Clone GitHub - fir-lang/fir: Fir programming language, make debug and release builds with cargo build.
  • export FIR_ROOT=<repo directory>
  • Then in the repo directory:
    time ./target/debug/fir compiler/Parser.fir -- tests/AndOrEvaluation.fir
time ./target/release/fir compiler/Parser.fir -- tests/AndOrEvaluation.fir

Outputs on my system with the latest Rust stable:

./target/debug/fir compiler/Parser.fir -- tests/AndOrEvaluation.fir  0.24s user 0.03s system 99% cpu 0.268 total
./target/release/fir compiler/Parser.fir -- tests/AndOrEvaluation.fir  0.04s user 0.02s system 5% cpu 1.115 total
4

Abort may be causing the system to capture a core dump, while a panic unwind past main will just exit with status 101.

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5

That's it, thanks.

6

Can you also check panic_immediate_abort?

7 
error: failed to parse manifest at `/home/omer/fir/fir/Cargo.toml`

Caused by:
  `panic` setting of `panic_immediate_abort` is not a valid setting, must be `unwind` or `abort`
8

It is not a strategy, it is a compiler flag!

cargo +nightly build -Z build-std-features=panic_immediate_abort
9

I was under the impression you also had to instruct the compiler to build core/alloc/std? For example, instead of passing the flags explicitly to cargo/rustc, one can add the following tables to ~/.cargo/config.toml:

[profile.release]
lto = true
panic = 'abort'
strip = true

[unstable]
build-std = ["core"] # or ["alloc"] or ["std"]
build-std-features = ["panic_immediate_abort"]

Then build it by running cargo +nightly build --release. Admittedly I have almost no experience using Cargo's unstable features, so perhaps passing build-std-features is sufficient.

2 Likes
10

In any case, that's still going through intrinsics::abort, so the system core dump will remain.

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