diff --git a/src/tokio/child/unix.rs b/src/tokio/child/unix.rs index 52f5fdc..db6cf9d 100644 --- a/src/tokio/child/unix.rs +++ b/src/tokio/child/unix.rs @@ -1,6 +1,7 @@ use std::{ convert::TryInto, io::{Error, Result}, + ops::ControlFlow, os::unix::process::ExitStatusExt, process::ExitStatus, }; @@ -69,7 +70,7 @@ impl ChildImp { self.inner.id() } - fn wait_imp(pgid: i32, flag: WaitPidFlag) -> Result> { + fn wait_imp(pgid: i32, flag: WaitPidFlag) -> Result>> { // Wait for processes in a loop until every process in this // process group has exited (this ensures that we reap any // zombies that may have been created if the parent exited after @@ -85,14 +86,14 @@ impl ChildImp { 0 => { // Zero should only happen if WNOHANG was passed in, // and means that no processes have yet to exit. - return Ok(None); + return Ok(ControlFlow::Continue(())); } -1 => { match Errno::last() { Errno::ECHILD => { // No more children to reap; this is a // graceful exit. - return Ok(parent_exit_status); + return Ok(ControlFlow::Break(parent_exit_status)); } errno => { return Err(Error::from(errno)); @@ -115,24 +116,33 @@ impl ChildImp { } pub async fn wait(&mut self) -> Result { - if let Some(status) = self.try_wait()? { - return Ok(status); - } + const MAX_RETRY_ATTEMPT: usize = 10; + + // Always wait for parent to exit first. + // + // It's likely that all its children has already exited and reaped by + // the time the parent exits. + let status = self.inner.wait().await?; let pgid = self.pgid.as_raw(); - match spawn_blocking(move || Self::wait_imp(pgid, WaitPidFlag::empty())) - .await? - .transpose() - { - None => self.inner.wait().await, - Some(status) => status, + + // Try reaping all children, if there are some that are still alive after + // several attempts, then spawn a blocking task to reap them. + for retry_attempt in 1..=MAX_RETRY_ATTEMPT { + if Self::wait_imp(pgid, WaitPidFlag::WNOHANG)?.is_break() { + break; + } else if retry_attempt == MAX_RETRY_ATTEMPT { + spawn_blocking(move || Self::wait_imp(pgid, WaitPidFlag::empty())).await??; + } } + + Ok(status) } pub fn try_wait(&mut self) -> Result> { - match Self::wait_imp(self.pgid.as_raw(), WaitPidFlag::WNOHANG) { - Ok(None) => self.inner.try_wait(), - otherwise => otherwise, + match Self::wait_imp(self.pgid.as_raw(), WaitPidFlag::WNOHANG)? { + ControlFlow::Break(res) => Ok(res), + ControlFlow::Continue(()) => self.inner.try_wait(), } } }