[pbs-devel] [PATCH proxmox-backup v2] api2/node/termproxy: fix zombies on worker abort
Dominik Csapak
d.csapak at proxmox.com
Wed Jul 29 13:50:27 CEST 2020
tokios kill_on_drop sometimes leaves zombies around, especially
when there is not another tokio::process::Command spawned after
so instead of relying on the 'kill_on_drop' feature, we explicitly
kill the child on a worker abort. to be able to do this
we have to use 'tokio::select' instead of 'futures::select' since
the latter requires the future to be fused, which consumes the
child handle, leaving us no possibility to kill it after fusing.
(tokio::select does not need the futures to be fused, so we
can reuse the child future after the select again)
Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
changes from v1:
* if the worker future is ok, bubble errors up from child kill/await
if the worker future is err, log errors from kill/await and return
the error from the abort
src/api2/node.rs | 36 ++++++++++++++++++++++++++----------
1 file changed, 26 insertions(+), 10 deletions(-)
diff --git a/src/api2/node.rs b/src/api2/node.rs
index 9be5fe6d..5a3ea0ff 100644
--- a/src/api2/node.rs
+++ b/src/api2/node.rs
@@ -2,10 +2,7 @@ use std::net::TcpListener;
use std::os::unix::io::AsRawFd;
use anyhow::{bail, format_err, Error};
-use futures::{
- future::{FutureExt, TryFutureExt},
- select,
-};
+use futures::future::{FutureExt, TryFutureExt};
use hyper::body::Body;
use hyper::http::request::Parts;
use hyper::upgrade::Upgraded;
@@ -172,7 +169,6 @@ async fn termproxy(
let mut cmd = tokio::process::Command::new("/usr/bin/termproxy");
cmd.args(&arguments)
- .kill_on_drop(true)
.stdout(std::process::Stdio::piped())
.stderr(std::process::Stdio::piped());
@@ -199,8 +195,9 @@ async fn termproxy(
Ok::<(), Error>(())
};
- select!{
- res = child.fuse() => {
+ let mut needs_kill = false;
+ let res = tokio::select!{
+ res = &mut child => {
let exit_code = res?;
if !exit_code.success() {
match exit_code.code() {
@@ -210,10 +207,29 @@ async fn termproxy(
}
Ok(())
},
- res = stdout_fut.fuse() => res,
- res = stderr_fut.fuse() => res,
- res = worker.abort_future().fuse() => res.map_err(Error::from),
+ res = stdout_fut => res,
+ res = stderr_fut => res,
+ res = worker.abort_future() => {
+ needs_kill = true;
+ res.map_err(Error::from)
+ }
+ };
+
+ if needs_kill {
+ if res.is_ok() {
+ child.kill()?;
+ child.await?;
+ return Ok(());
+ }
+
+ if let Err(err) = child.kill() {
+ worker.warn(format!("error killing termproxy: {}", err));
+ } else if let Err(err) = child.await {
+ worker.warn(format!("error awaiting termproxy: {}", err));
+ }
}
+
+ res
},
)?;
--
2.20.1
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