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Add SIGUSR1 handler for dumping stack/goroutine traces

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Add handler for SIGUSR1 based on feedback regarding when to dump
goroutine stacks.  This will also dump goroutine stack traces on SIGQUIT
followed by a hard-exit from the daemon.

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
This commit is contained in:
Phil Estes 2015-04-21 00:24:24 -04:00
parent 2c617078a7
commit 28f561297c
1 changed files with 21 additions and 11 deletions
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32
signal/trap.go
View file

@ -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)
}