posix_spawn: Unconditionally default all signals (except HUP)#10869
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We don't really care if the process has a custom handler installed, we
can just set it to default.
The one we check is SIGHUP, which may be given to us via `nohup`.
This saves ~30 syscalls *per process* we spawn, so:
```fish
for f in (seq 1000)
command true
end
```
has ~30000 fewer rt_sigaction calls. These take up about ~30% of the
total time spent in syscalls according to strace.
We could also compute this set once at startup and then reuse it.
ridiculousfish
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Nov 30, 2024
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Great find! I can't think of any reason to not do this.
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yeah we can cache these indefinitely, other shells do that too |
faho
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Dec 4, 2024
Really the only thing we're looking for here is if we're started with HUP ignored or not. Saves a syscall per external process. Continuation of #10869
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As I understand it, we want all signals for processes we spawn (except for HUP, because of nohup) to have the default signal handlers.
So I don't know why we need to check what action a specific signal currently has, we can just default it anyway.
This saves ~30 syscalls per process we spawn, so:
has ~30000 fewer rt_sigaction calls. These take up about ~30% of the total time spent in syscalls according to strace.
We could also compute this set once at startup and then reuse it.