Remove exec PID files after use to prevent memory leaks

We have another patch running to do the same for exit files, with
a much more in-depth explanation of why it's necessary. Suffice
to say that persistent files in tmpfs tied to container CGroups
lead to significant memory allocations that last for the lifetime
of the file.

Based on a patch by Andrea Arcangeli (aarcange@redhat.com).

Signed-off-by: Matthew Heon <mheon@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/libpod/container_api.go b/libpod/container_api.go
index c52b27db3..1de956521 100644
--- a/libpod/container_api.go
+++ b/libpod/container_api.go
@@ -301,6 +301,11 @@ func (c *Container) Exec(tty, privileged bool, env, cmd []string, user, workDir
 	if err != nil {
 		if exited {
 			// If the runtime exited, propagate the error we got from the process.
+			// We need to remove PID files to ensure no memory leaks
+			if err2 := os.Remove(pidFile); err2 != nil {
+				logrus.Errorf("Error removing exit file for container %s exec session %s: %v", c.ID(), sessionID, err2)
+			}
+
 			return err
 		}
 		return errors.Wrapf(err, "timed out waiting for runtime to create pidfile for exec session in container %s", c.ID())
@@ -308,6 +313,10 @@ func (c *Container) Exec(tty, privileged bool, env, cmd []string, user, workDir
 
 	// Pidfile exists, read it
 	contents, err := ioutil.ReadFile(pidFile)
+	// We need to remove PID files to ensure no memory leaks
+	if err2 := os.Remove(pidFile); err2 != nil {
+		logrus.Errorf("Error removing exit file for container %s exec session %s: %v", c.ID(), sessionID, err2)
+	}
 	if err != nil {
 		// We don't know the PID of the exec session
 		// However, it may still be alive