diff --git a/signal/trap.go b/signal/trap.go index 7469dbc..3772db5 100644 --- a/signal/trap.go +++ b/signal/trap.go @@ -3,6 +3,7 @@ package signal import ( "os" gosignal "os/signal" + "runtime" "sync/atomic" "syscall" @@ -14,41 +15,50 @@ import ( // (and the Docker engine in particular). // // * If SIGINT or SIGTERM are received, `cleanup` is called, then the process is terminated. -// * If SIGINT or SIGTERM are repeated 3 times before cleanup is complete, then cleanup is -// skipped and the process terminated directly. -// * If "DEBUG" is set in the environment, SIGQUIT causes an exit without cleanup. +// * If SIGINT or SIGTERM are received 3 times before cleanup is complete, then cleanup is +// skipped and the process is terminated immediately (allows force quit of stuck daemon) +// * A SIGQUIT always causes an exit without cleanup, with a goroutine dump preceding exit. // func Trap(cleanup func()) { c := make(chan os.Signal, 1) - signals := []os.Signal{os.Interrupt, syscall.SIGTERM} - if os.Getenv("DEBUG") == "" { - signals = append(signals, syscall.SIGQUIT) - } + // we will handle INT, TERM, QUIT here + signals := []os.Signal{os.Interrupt, syscall.SIGTERM, syscall.SIGQUIT} gosignal.Notify(c, signals...) go func() { interruptCount := uint32(0) for sig := range c { go func(sig os.Signal) { - logrus.Infof("Received signal '%v', starting shutdown of docker...", sig) + logrus.Infof("Processing signal '%v'", sig) switch sig { case os.Interrupt, syscall.SIGTERM: - // If the user really wants to interrupt, let him do so. if atomic.LoadUint32(&interruptCount) < 3 { // Initiate the cleanup only once if atomic.AddUint32(&interruptCount, 1) == 1 { - // Call cleanup handler + // Call the provided cleanup handler cleanup() os.Exit(0) } else { return } } else { - logrus.Infof("Force shutdown of docker, interrupting cleanup") + // 3 SIGTERM/INT signals received; force exit without cleanup + logrus.Infof("Forcing docker daemon shutdown without cleanup; 3 interrupts received") } case syscall.SIGQUIT: + DumpStacks() + logrus.Infof("Forcing docker daemon shutdown without cleanup on SIGQUIT") } + //for the SIGINT/TERM, and SIGQUIT non-clean shutdown case, exit with 128 + signal # os.Exit(128 + int(sig.(syscall.Signal))) }(sig) } }() } + +func DumpStacks() { + buf := make([]byte, 16384) + buf = buf[:runtime.Stack(buf, true)] + // Note that if the daemon is started with a less-verbose log-level than "info" (the default), the goroutine + // traces won't show up in the log. + logrus.Infof("=== BEGIN goroutine stack dump ===\n%s\n=== END goroutine stack dump ===", buf) +}