talos/pkg/proc/reaper/reaper_test.go
Andrey Smirnov c0698c1815 chore(machined): implement process reaper for PID 1 machined process
In UNIX, any zombies without parent process get re-parented to process
with PID 1 (usually running init), and PID 1 process should take care of
them (usually simply clean them up). Cleaning up zombies is important,
as they still take kerner resources, and having enormous amount of
zombie processes signifcantly degrades system performance.

For Talos, PID 1 process is machined, and machined itself forks to run
other processes in process runner and `pkg/cmd` one-time commands. Naive
solution of running `wait()` loop doesn't work as it might race with
`Process.Wait()` and clean up zombie which wasn't re-parented which
leads to process execution false failure.

After considering other solutions, we decided to go with the simple
approach: machined runs global zombie process reaper which publishes
information about reaped zombies. Any call to `Process.Wait()` (or
`Command.Wait()` which calls it) should be replaced with listening to
reaper's channel for notifications to catch info about the process which
was created in this call.

There are several changes in this PR:

1. Reaper implementation itself, started from machined.

2. Process runner and `pkg/cmd` can either use regular `Command.Wait()`
or use reaper notifications depending on reaper status (running/not
running). This allows using this code outside of machined.

3. Small bug fixes with process log which was affecting the tests.

Signed-off-by: Andrey Smirnov <smirnov.andrey@gmail.com>
2019-09-05 10:01:02 -07:00

190 lines
3.8 KiB
Go

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package reaper_test
import (
"os/exec"
"sort"
"testing"
"time"
"github.com/stretchr/testify/suite"
"github.com/talos-systems/talos/pkg/proc/reaper"
)
type ReaperSuite struct {
suite.Suite
}
func (suite *ReaperSuite) SetupSuite() {
reaper.Run()
}
func (suite *ReaperSuite) TearDownSuite() {
reaper.Shutdown()
}
func (suite *ReaperSuite) TestNoActivity() {
}
func (suite *ReaperSuite) TestNoNotify() {
const N = 5
commands := make([]*exec.Cmd, N)
for i := range commands {
commands[i] = exec.Command("/bin/sh", "-c", ":")
suite.Assert().NoError(commands[i].Start())
}
// let the reaper do the work
time.Sleep(time.Second)
// zombies should have been reaped, so `Wait()` should fail
for i := range commands {
suite.Assert().EqualError(commands[i].Wait(), "waitid: no child processes")
}
}
//nolint: gocyclo
func (suite *ReaperSuite) TestNotifyStop() {
const N = 5
commands := make([]*exec.Cmd, N)
notifyCh := make([]chan reaper.ProcessInfo, 2)
for j := range notifyCh {
notifyCh[j] = make(chan reaper.ProcessInfo, N)
reaper.Notify(notifyCh[j])
}
expectedPids := make([]int, N)
for i := range commands {
commands[i] = exec.Command("/bin/sh", "-c", ":")
suite.Require().NoError(commands[i].Start())
expectedPids[i] = commands[i].Process.Pid
}
sort.Ints(expectedPids)
for _, ch := range notifyCh {
gotPids := make([]int, N)
for i := range gotPids {
info := <-ch
suite.T().Log(info)
gotPids[i] = info.Pid
suite.Assert().True(info.Status.Exited())
suite.Assert().Equal(0, info.Status.ExitStatus())
}
sort.Ints(gotPids)
suite.Assert().Equal(expectedPids, gotPids)
}
// zombies should have been reaped, so `Wait()` should fail
for i := range commands {
suite.Assert().EqualError(commands[i].Wait(), "waitid: no child processes")
}
for _, ch := range notifyCh {
select {
case <-ch:
suite.Require().Fail("there should be no more notifications in the channel")
default:
}
}
reaper.Stop(notifyCh[0])
command := exec.Command("/bin/sh", "-c", ":")
suite.Require().NoError(command.Start())
// notification should come on still active notify channel
<-notifyCh[1]
select {
case <-notifyCh[0]:
suite.Require().Fail("there should be no notifications after Stop")
default:
}
for j := range notifyCh {
reaper.Stop(notifyCh[j])
}
}
func (suite *ReaperSuite) TestFailedProcess() {
notifyCh := make(chan reaper.ProcessInfo, 1)
reaper.Notify(notifyCh)
defer reaper.Stop(notifyCh)
command := exec.Command("/bin/sh", "-c", "exit 3")
suite.Require().NoError(command.Start())
info := <-notifyCh
suite.Assert().Equal(command.Process.Pid, info.Pid)
suite.Assert().True(info.Status.Exited())
suite.Assert().Equal(3, info.Status.ExitStatus())
suite.Assert().EqualError(command.Wait(), "waitid: no child processes")
}
func (suite *ReaperSuite) TestWait() {
type args struct {
name string
args []string
}
tests := []struct {
args args
errString string
}{
{
args{
"true",
[]string{},
},
"",
},
{
args{
"false",
[]string{},
},
"exit status 1",
},
{
args{
"/bin/sh",
[]string{
"-c",
"kill -2 $$",
},
},
"signal: interrupt",
},
}
notifyCh := make(chan reaper.ProcessInfo, 1)
suite.Require().True(reaper.Notify(notifyCh))
defer reaper.Stop(notifyCh)
for _, t := range tests {
cmd := exec.Command(t.args.name, t.args.args...)
suite.Require().NoError(cmd.Start())
err := reaper.WaitWrapper(true, notifyCh, cmd)
if t.errString == "" {
suite.Assert().NoError(err)
} else {
suite.Assert().EqualError(err, t.errString)
}
}
}
func TestReaperSuite(t *testing.T) {
suite.Run(t, new(ReaperSuite))
}