[pbs-devel] [PATCH proxmox-backup 7/9] file-restore-daemon: limit concurrent download calls
Stefan Reiter
s.reiter at proxmox.com
Thu May 6 17:26:22 CEST 2021
While the issue with vsock packets starving kernel memory is mostly
worked around by the '64k -> 4k buffer' patch in
'proxmox-backup-restore-image', let's be safe and also limit the number
of concurrent transfers. 8 downloads per VM seems like a fair value.
Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
---
Mostly optional, included since I had it lying around for a while, but only now
is it useable, since it suffered from the same tokio issue as the watchdog
inhibit.
src/bin/proxmox_restore_daemon/api.rs | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/src/bin/proxmox_restore_daemon/api.rs b/src/bin/proxmox_restore_daemon/api.rs
index c578b2c0..f2732e64 100644
--- a/src/bin/proxmox_restore_daemon/api.rs
+++ b/src/bin/proxmox_restore_daemon/api.rs
@@ -6,6 +6,7 @@ use hyper::{header, Body, Response, StatusCode};
use log::error;
use pathpatterns::{MatchEntry, MatchPattern, MatchType, Pattern};
use serde_json::Value;
+use tokio::sync::Semaphore;
use std::ffi::OsStr;
use std::fs;
@@ -41,6 +42,8 @@ pub const ROUTER: Router = Router::new()
.get(&list_subdirs_api_method!(SUBDIRS))
.subdirs(SUBDIRS);
+static DOWNLOAD_SEM: Semaphore = Semaphore::const_new(8);
+
fn read_uptime() -> Result<f32, Error> {
let uptime = fs::read_to_string("/proc/uptime")?;
// unwrap the Option, if /proc/uptime is empty we have bigger problems
@@ -252,6 +255,12 @@ fn extract(
let _inhibitor = watchdog_inhibit();
async move {
let _inhibitor = _inhibitor;
+
+ let _permit = match DOWNLOAD_SEM.try_acquire() {
+ Ok(permit) => permit,
+ Err(_) => bail!("maximum concurrent download limit reached, please wait for another restore to finish before attempting a new one"),
+ };
+
let path = tools::required_string_param(¶m, "path")?;
let mut path = base64::decode(path)?;
if let Some(b'/') = path.last() {
@@ -286,6 +295,7 @@ fn extract(
if pxar {
tokio::spawn(async move {
let _inhibitor = _inhibitor;
+ let _permit = _permit;
let result = async move {
// pxar always expects a directory as it's root, so to accommodate files as
// well we encode the parent dir with a filter only matching the target instead
@@ -344,6 +354,7 @@ fn extract(
} else {
tokio::spawn(async move {
let _inhibitor = _inhibitor;
+ let _permit = _permit;
let result = async move {
if vm_path.is_dir() {
zip_directory(&mut writer, &vm_path).await?;
--
2.20.1
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