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Retry to fork/spawn with exponential backoff

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This commit is contained in:
Florian Bartels 2023-03-18 18:45:51 +01:00
parent 0939ec13d8
commit bdb475cf6c
1 changed files with 44 additions and 10 deletions
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54
library/std/src/sys/unix/process/process_unix.rs
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@ -35,8 +35,20 @@ cfg_if::cfg_if! {
if #[cfg(all(target_os = "nto", target_env = "nto71"))] {
use crate::thread;
use libc::{c_char, posix_spawn_file_actions_t, posix_spawnattr_t};
// arbitrary number of tries:
const MAX_FORKSPAWN_TRIES: u32 = 4;
use crate::time::Duration;
// Get smallest amount of time we can sleep.
// Return a common value if it cannot be determined.
fn get_clock_resolution() -> Duration {
let mut mindelay = libc::timespec { tv_sec: 0, tv_nsec: 0 };
if unsafe { libc::clock_getres(libc::CLOCK_MONOTONIC, &mut mindelay) } == 0
{
Duration::from_nanos(mindelay.tv_nsec as u64)
} else {
Duration::from_millis(1)
}
}
// Arbitrary minimum sleep duration for retrying fork/spawn
const MIN_FORKSPAWN_SLEEP: Duration = Duration::from_nanos(1);
}
}
@ -163,12 +175,24 @@ impl Command {
unsafe fn do_fork(&mut self) -> Result<(pid_t, pid_t), io::Error> {
use crate::sys::os::errno;
let mut tries_left = MAX_FORKSPAWN_TRIES;
let mut minimum_delay = None;
let mut delay = MIN_FORKSPAWN_SLEEP;
loop {
let r = libc::fork();
if r == -1 as libc::pid_t && tries_left > 0 && errno() as libc::c_int == libc::EBADF {
thread::yield_now();
tries_left -= 1;
if r == -1 as libc::pid_t && errno() as libc::c_int == libc::EBADF {
if minimum_delay.is_none() {
minimum_delay = Some(get_clock_resolution());
}
if delay < minimum_delay.unwrap() {
// We cannot sleep this short (it would be longer).
// Yield instead.
thread::yield_now();
} else {
thread::sleep(delay);
}
delay *= 2;
continue;
} else {
return cvt(r).map(|res| (res, -1));
}
@ -481,12 +505,22 @@ impl Command {
argv: *const *mut c_char,
envp: *const *mut c_char,
) -> i32 {
let mut tries_left = MAX_FORKSPAWN_TRIES;
let mut minimum_delay = None;
let mut delay = MIN_FORKSPAWN_SLEEP;
loop {
match libc::posix_spawnp(pid, file, file_actions, attrp, argv, envp) {
libc::EBADF if tries_left > 0 => {
thread::yield_now();
tries_left -= 1;
libc::EBADF => {
if minimum_delay.is_none() {
minimum_delay = Some(get_clock_resolution());
}
if delay < minimum_delay.unwrap() {
// We cannot sleep this short (it would be longer).
// Yield instead.
thread::yield_now();
} else {
thread::sleep(delay);
}
delay *= 2;
continue;
}
r => {