process.uptime() not correct when adjust time #2573

Activity

1. ChALkeR

   added

   processIssues and PRs related to the process subsystem.Issues and PRs related to the process subsystem.

   on Aug 27, 2015
2. bnoordhuis commented on Aug 27, 2015

   

   bnoordhuis

   on Aug 27, 2015

   Member

   More actions

   but when call settimeofday to change time, process.time isn't correct

   process.time is a typo of process.uptime?

   On what platform are you seeing this? I'm not sure I understand, libuv uses monotonic clocks - i.e. clocks that are unaffected by settimeofday - whenever possible.
3. yjhjstz commented on Aug 27, 2015

   

   yjhjstz

   on Aug 27, 2015

   Author

   More actions

   I mean js-function process.time() implemented in static void Uptime(...).

   diff --git a/src/node.cc b/src/node.cc
   index b900388..1751f09 100644
   --- a/src/node.cc
   +++ b/src/node.cc
   @@ -1972,10 +1972,10 @@ static void Uptime(const FunctionCallbackInfo<Value>& args) {
      Environment* env = Environment::GetCurrent(args);
      double uptime;
   
   -  uv_update_time(env->event_loop());
   -  uptime = uv_now(env->event_loop()) - prog_start_time;
   +  uv_uptime(&uptime);
   +  uptime -= prog_start_time;
   
   -  args.GetReturnValue().Set(Number::New(env->isolate(), uptime / 1000));
   +  args.GetReturnValue().Set(Number::New(env->isolate(), uptime));
    }
   
   @@ -3606,8 +3606,7 @@ void Init(int* argc,
              int* exec_argc,
              const char*** exec_argv) {
      // Initialize prog_start_time to get relative uptime.
   -  prog_start_time = static_cast<double>(uv_now(uv_default_loop()));
   -
   +  uv_uptime(&prog_start_time);
      // Make inherited handles noninheritable.

   uv_now() can be affected by settimeofday, so I use uv_uptime(). @bnoordhuis
4. bnoordhuis commented on Aug 27, 2015

   

   bnoordhuis

   on Aug 27, 2015

   Member

   More actions

   I mean js-function process.time() implemented in static void Uptime(...).

   There is no process.time() but I understand that you mean process.uptime(). I ask because there is also process.hrtime() which does something else.

   uv_now() can be affected by settimeofday, so I use uv_uptime().

   Can you explain how? Like I said, libuv uses monotonic clocks (think clock_gettime(CLOCK_MONOTONIC)) on most platforms. You should never see the uptime jump backwards, although it is possible for a monotonic clock to slow down in the presence of time adjustments.

   On some platforms it doesn't matter if you use uv_now() or uv_uptime() because they both call clock_gettime(). With that in mind, can you explain more about the exact behavior you're seeing and on what platform?
5. yjhjstz commented on Aug 27, 2015

   

   yjhjstz

   on Aug 27, 2015

   Author

   More actions

   in netbsd,

   int uv_uptime(double* uptime) {
     time_t now;
     struct timeval info;
     size_t size = sizeof(info);
     static int which[] = {CTL_KERN, KERN_BOOTTIME};
   
     if (sysctl(which, 2, &info, &size, NULL, 0))
       return -errno;
   
     now = time(NULL);
   
     *uptime = (double)(now - info.tv_sec);
     return 0;
   }
   uint64_t uv__hrtime(uv_clocktype_t type) {
     struct timespec ts;
     clock_gettime(CLOCK_MONOTONIC, &ts);
     return (((uint64_t) ts.tv_sec) * NANOSEC + ts.tv_nsec);
   }

   I want to know, why uv_uptime not use clock_gettime, but to use sysctl?
6. bnoordhuis commented on Aug 27, 2015

   

   bnoordhuis

   on Aug 27, 2015

   Member

   More actions

   I don't know the exact reason. Someone (@shigeki?) contributed that code a long time ago.
7. mscdex commented on Aug 27, 2015

   

   mscdex

   on Aug 27, 2015

   Contributor

   More actions

   All of the BSDs use the same uv_uptime() implementation in libuv. process.uptime() uses a monotonic clock via uv_hrtime() whereas require('os').uptime() uses uv_uptime(). So are you referring to os.uptime() instead of process.uptime()?
8. shigeki commented on Aug 28, 2015

   

   shigeki

   on Aug 28, 2015

   Contributor

   More actions

   I forgot the detail when I submitted netBSD patch in 3 years ago. Probably I referred FreeBSD implementation of uv_uptime().

   I guess it comes from an old implementation of uptime(1) in FreeBSD and it was changed and has been using clock_gettime since 2005 as in freebsd/freebsd-src@74d3dde. We can change it in libuv now.
9. yjhjstz commented on Aug 28, 2015

   

   yjhjstz

   on Aug 28, 2015

   Author

   More actions

   I think , we can update libuv implementation. And I was wondering why os.uptime() implementation is different from process.uptime() .
10. saghul commented on Aug 31, 2015

    

    saghul

    on Aug 31, 2015

    Member

    More actions

    FWIW, this landed in libuv, thanks @yjhjstz!
11. evanlucas commented on Oct 20, 2015

    

    evanlucas

    on Oct 20, 2015

    Contributor

    More actions

    This was fixed by the upgrade to libuv 1.7.5. Thanks!
12. evanlucas

    closed this as completedon Oct 20, 2015