From 070ce0c85570b79a3612ad1fdf15b5c1287b00b6 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Tue, 20 Nov 2018 11:06:20 +0100 Subject: exec: don't wait for pidfile when the runtime exited don't wait for the timeout to expire if the runtime process exited. I've noticed podman to hang on exit and keeping the container lock taken when the OCI runtime already exited. Additionally, it reduces the waiting time as we won't hit the 25 milliseconds waiting time in the worst case. Signed-off-by: Giuseppe Scrivano --- libpod/container_api.go | 24 +++++++++++++----------- libpod/util.go | 8 +++++--- 2 files changed, 18 insertions(+), 14 deletions(-) (limited to 'libpod') diff --git a/libpod/container_api.go b/libpod/container_api.go index df6b6e962..e1d5e15c4 100644 --- a/libpod/container_api.go +++ b/libpod/container_api.go @@ -328,6 +328,11 @@ func (c *Container) Exec(tty, privileged bool, env, cmd []string, user string) e if err != nil { return errors.Wrapf(err, "error exec %s", c.ID()) } + chWait := make(chan error) + go func() { + chWait <- execCmd.Wait() + }() + defer close(chWait) pidFile := c.execPidPath(sessionID) // 60 second seems a reasonable time to wait @@ -336,18 +341,12 @@ func (c *Container) Exec(tty, privileged bool, env, cmd []string, user string) e const pidWaitTimeout = 60000 // Wait until the runtime makes the pidfile - // TODO: If runtime errors before the PID file is created, we have to - // wait for timeout here - if err := WaitForFile(pidFile, pidWaitTimeout*time.Millisecond); err != nil { - logrus.Debugf("Timed out waiting for pidfile from runtime for container %s exec", c.ID()) - - // Check if an error occurred in the process before we made a pidfile - // TODO: Wait() here is a poor choice - is there a way to see if - // a process has finished, instead of waiting for it to finish? - if err := execCmd.Wait(); err != nil { + exited, err := WaitForFile(pidFile, chWait, pidWaitTimeout*time.Millisecond) + if err != nil { + if exited { + // If the runtime exited, propagate the error we got from the process. return err } - return errors.Wrapf(err, "timed out waiting for runtime to create pidfile for exec session in container %s", c.ID()) } @@ -389,7 +388,10 @@ func (c *Container) Exec(tty, privileged bool, env, cmd []string, user string) e locked = false } - waitErr := execCmd.Wait() + var waitErr error + if !exited { + waitErr = <-chWait + } // Lock again if !c.batched { diff --git a/libpod/util.go b/libpod/util.go index 7007b29cd..25e78bd01 100644 --- a/libpod/util.go +++ b/libpod/util.go @@ -90,7 +90,7 @@ func MountExists(specMounts []spec.Mount, dest string) bool { } // WaitForFile waits until a file has been created or the given timeout has occurred -func WaitForFile(path string, timeout time.Duration) error { +func WaitForFile(path string, chWait chan error, timeout time.Duration) (bool, error) { done := make(chan struct{}) chControl := make(chan struct{}) go func() { @@ -110,11 +110,13 @@ func WaitForFile(path string, timeout time.Duration) error { }() select { + case e := <-chWait: + return true, e case <-done: - return nil + return false, nil case <-time.After(timeout): close(chControl) - return errors.Wrapf(ErrInternal, "timed out waiting for file %s", path) + return false, errors.Wrapf(ErrInternal, "timed out waiting for file %s", path) } } -- cgit v1.2.3-54-g00ecf From fc3047322a527347072ce98ba183cbc8cb49231d Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Tue, 20 Nov 2018 11:19:40 +0100 Subject: util: use fsnotify to wait for file prefer a fsnotify watcher to polling the file, we take advantage of inotify on Linux and react more promptly to the PID file being created. If the watcher cannot be created, then fallback to the old polling mechanism. Signed-off-by: Giuseppe Scrivano --- libpod/util.go | 36 ++++++++++++++++++++++++++++++++++-- 1 file changed, 34 insertions(+), 2 deletions(-) (limited to 'libpod') diff --git a/libpod/util.go b/libpod/util.go index 25e78bd01..aa3494529 100644 --- a/libpod/util.go +++ b/libpod/util.go @@ -13,6 +13,7 @@ import ( "github.com/containers/image/signature" "github.com/containers/image/types" "github.com/containers/libpod/pkg/util" + "github.com/fsnotify/fsnotify" spec "github.com/opencontainers/runtime-spec/specs-go" "github.com/pkg/errors" ) @@ -93,18 +94,49 @@ func MountExists(specMounts []spec.Mount, dest string) bool { func WaitForFile(path string, chWait chan error, timeout time.Duration) (bool, error) { done := make(chan struct{}) chControl := make(chan struct{}) + + var inotifyEvents chan fsnotify.Event + var timer chan struct{} + watcher, err := fsnotify.NewWatcher() + if err == nil { + if err := watcher.Add(filepath.Dir(path)); err == nil { + inotifyEvents = watcher.Events + } + defer watcher.Close() + } + if inotifyEvents == nil { + // If for any reason we fail to create the inotify + // watcher, fallback to polling the file + timer = make(chan struct{}) + go func() { + select { + case <-chControl: + close(timer) + return + default: + time.Sleep(25 * time.Millisecond) + timer <- struct{}{} + } + }() + } + go func() { for { select { case <-chControl: return - default: + case <-timer: + _, err := os.Stat(path) + if err == nil { + close(done) + return + } + case <-inotifyEvents: _, err := os.Stat(path) if err == nil { close(done) return } - time.Sleep(25 * time.Millisecond) } } }() -- cgit v1.2.3-54-g00ecf