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performance improvement: setup signal notify in a new go routine

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There is a big loop(at least 65 times) in `signal.Notify`, it costs as much
time as `runc init`, so we can call it in parallel ro reduce the container
start time. In a general test, it can be reduced about 38.70%.

Signed-off-by: lifubang <lifubang@acmcoder.com>
(cyphar: move signal channel definition inside goroutine)
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
This commit is contained in:
lifubang
2025-02-28 15:09:36 +00:00
committed by Aleksa Sarai
parent 202ca99fae
commit d92dd22611
2 changed files with 20 additions and 11 deletions
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28
signals.go
View File

@@ -18,22 +18,30 @@ const signalBufferSize = 2048
// while still forwarding all other signals to the process.
// If notifySocket is present, use it to read systemd notifications from the container and
// forward them to notifySocketHost.
func newSignalHandler(enableSubreaper bool, notifySocket *notifySocket) *signalHandler {
func newSignalHandler(enableSubreaper bool, notifySocket *notifySocket) chan *signalHandler {
if enableSubreaper {
// set us as the subreaper before registering the signal handler for the container
if err := system.SetSubreaper(1); err != nil {
logrus.Warn(err)
}
}
// ensure that we have a large buffer size so that we do not miss any signals
// in case we are not processing them fast enough.
s := make(chan os.Signal, signalBufferSize)
// handle all signals for the process.
signal.Notify(s)
return &signalHandler{
signals: s,
notifySocket: notifySocket,
}
handler := make(chan *signalHandler)
// signal.Notify is actually quite expensive, as it has to configure the
// signal mask and add signal handlers for all signals (all ~65 of them).
// So, defer this to a background thread while doing the rest of the io/tty
// setup.
go func() {
// ensure that we have a large buffer size so that we do not miss any
// signals in case we are not processing them fast enough.
s := make(chan os.Signal, signalBufferSize)
// handle all signals for the process.
signal.Notify(s)
handler <- &signalHandler{
signals: s,
notifySocket: notifySocket,
}
}()
return handler
}
// exit models a process exit status with the pid and

3
utils_linux.go
View File

@@ -246,7 +246,7 @@ func (r *runner) run(config *specs.Process) (int, error) {
// Setting up IO is a two stage process. We need to modify process to deal
// with detaching containers, and then we get a tty after the container has
// started.
handler := newSignalHandler(r.enableSubreaper, r.notifySocket)
handlerCh := newSignalHandler(r.enableSubreaper, r.notifySocket)
tty, err := setupIO(process, r.container, config.Terminal, detach, r.consoleSocket)
if err != nil {
return -1, err
@@ -285,6 +285,7 @@ func (r *runner) run(config *specs.Process) (int, error) {
return -1, err
}
}
handler := <-handlerCh
status, err := handler.forward(process, tty, detach)
if err != nil {
r.terminate(process)