diff options
| -rw-r--r-- | usr/austin/ptrace/ptrace-nptl.txt | 3 | ||||
| -rw-r--r-- | usr/austin/ptrace/ptrace_linux.go | 39 |
2 files changed, 33 insertions, 9 deletions
diff --git a/usr/austin/ptrace/ptrace-nptl.txt b/usr/austin/ptrace/ptrace-nptl.txt index c52640473..62cbf7700 100644 --- a/usr/austin/ptrace/ptrace-nptl.txt +++ b/usr/austin/ptrace/ptrace-nptl.txt @@ -115,7 +115,8 @@ don't think the process is done until all of the threads have exited. Unfortunately, signals cannot be delivered to non-waitable zombies. Most notably, SIGSTOP cannot be delivered; as a result, when you broadcast SIGSTOP to all of the threads, you must not wait for -non-waitable zombies to stop. +non-waitable zombies to stop. Furthermore, any ptrace command on a +non-waitable zombie, including PTRACE_DETACH, will return ESRCH. == Multi-threaded debuggers == diff --git a/usr/austin/ptrace/ptrace_linux.go b/usr/austin/ptrace/ptrace_linux.go index 43a509401..b1e1b3da9 100644 --- a/usr/austin/ptrace/ptrace_linux.go +++ b/usr/austin/ptrace/ptrace_linux.go @@ -43,7 +43,21 @@ const ( */ // Each thread can be in one of the following set of states. -// Each state satisfies (isRunning() || isStopped() || isTerminal()). +// Each state satisfies +// isRunning() || isStopped() || isZombie() || isTerminal(). +// +// Running threads can be sent signals and must be waited on, but they +// cannot be inspected using ptrace. +// +// Stopped threads can be inspected and continued, but cannot be +// meaningfully waited on. They can be sent signals, but the signals +// will be queued until they are running again. +// +// Zombie threads cannot be inspected, continued, or sent signals (and +// therefore they cannot be stopped), but they must be waited on. +// +// Terminal threads no longer exist in the OS and thus you can't do +// anything with them. type threadState string; const ( @@ -61,13 +75,17 @@ const ( ) func (ts threadState) isRunning() bool { - return ts == running || ts == singleStepping || ts == stopping || ts == exiting; + return ts == running || ts == singleStepping || ts == stopping; } func (ts threadState) isStopped() bool { return ts == stopped || ts == stoppedBreakpoint || ts == stoppedSignal || ts == stoppedThreadCreate || ts == stoppedExiting; } +func (ts threadState) isZombie() bool { + return ts == exiting; +} + func (ts threadState) isTerminal() bool { return ts == exited || ts == detached; } @@ -429,7 +447,7 @@ func (t *thread) setState(new threadState) { t.state = new; t.logTrace("state %v -> %v", old, new); - if !old.isRunning() && new.isRunning() { + if !old.isRunning() && (new.isRunning() || new.isZombie()) { // Start waiting on this thread go t.wait(); } @@ -1020,7 +1038,11 @@ func (p *process) Continue() os.Error { if err != nil { return err; } - t.setState(running); + if t.state == stoppedExiting { + t.setState(exiting); + } else { + t.setState(running); + } } return nil; }); @@ -1050,8 +1072,6 @@ func (p *process) WaitStop() os.Error { h := &transitionHandler{}; h.handle = func (st *thread, old, new threadState) { if !new.isRunning() { - // TODO(austin) This gets stuck on - // zombie threads. if p.someRunningThread() == nil { ready <- nil; return; @@ -1094,8 +1114,11 @@ func (p *process) Detach() os.Error { } for pid, t := range p.threads { - if err := t.ptraceDetach(); err != nil { - return err; + if t.state.isStopped() { + // We can't detach from zombies. + if err := t.ptraceDetach(); err != nil { + return err; + } } t.setState(detached); p.threads[pid] = nil, false; |