From: Skip Tavakkolian <skip.tavakkolian@gmail.com>
To: 9fans <9fans@9fans.net>
Subject: Re: [9fans] syscall silently kill processes
Date: Fri, 17 Jun 2022 09:11:28 -0700 [thread overview]
Message-ID: <CAJSxfmKHKa1+eUUji2+wdoS2AEuk1ahCs6wYykgCBaZdNn+WXQ@mail.gmail.com> (raw)
In-Reply-To: <CAJSxfmJsAUURUZzE2OcHxNa2=ec7dnOudK-3q82msbjG2F0VFw@mail.gmail.com>
it's worth grepping for persistent magic constants:
% grep 33 /sys/src/libthread/*.[ch]
/sys/src/libthread/note.c:#define NFN 33
On Fri, Jun 17, 2022 at 9:08 AM Skip Tavakkolian
<skip.tavakkolian@gmail.com> wrote:
>
> interesting catch. it seems to be a tunable limit.
>
> % grep NFN /sys/src/libthread/note.c
> #define NFN 33
> static int (*onnote[NFN])(void*, char*);
> static int onnotepid[NFN];
> for(i=0; i<NFN; i++)
> return i<NFN;
> for(i=0; i<NFN; i++){
> if(i==NFN){
>
> On Fri, Jun 17, 2022 at 8:08 AM <andrey100100100@gmail.com> wrote:
> >
> > В Пт, 17/06/2022 в 08:11 -0600, Jacob Moody пишет:
> > > On 6/17/22 07:46, Thaddeus Woskowiak wrote:
> > > > I believe threadnotify() should be called from threadmain() to
> > > > properly register the handler in the rendez group
> > >
> > > This is incorrect, according to thread(2):
> > >
> > > "The thread library depends on all procs
> > > being in the same rendezvous group"
> >
> >
> > From sleep(2):
> >
> > Alarm causes an alarm note (see notify(2)) to be sent to the
> > invoking process after the number of milliseconds given by
> > the argument.
> >
> > Mean to be sent only to the invoking process, NOT to the process group.
> >
> > >
> > > The issue here is that your note handler has to call noted,
> > > you are returning from the handler without actually resuming the
> > > program.
> > > You either need to call noted(NCONT) to resume execution or
> > > noted(NDFLT)
> > > to stop execution.
> > >
> > > An excerpt from notify(2):
> > >
> > > "A notification handler must finish either by exiting the
> > > program or by calling noted; if the handler returns the
> > > behavior is undefined and probably erroneous."
> > >
> > > So you are indeed observing undefined behavior.
> > >
> >
> > With:
> >
> > ------------------------------------
> > static int
> > handler_alarm(void *, char *msg)
> > {
> > if(strstr(msg, "alarm")){
> > noted(NCONT);
> > return 1;
> > }
> >
> > return 0;
> > }
> > ------------------------------------
> >
> > result the same:
> >
> > cpu% 6.out | grep end | wc -l
> > 33
> >
> >
> > And noted(NCONT) may be needed, when process recieved many (2 and more)
> > notes at once.
> >
> > May be something wrong with interrupted an incomplete system call?
> >
> >
> > >
> > > Hope this helps,
> > > moody
> > >
> >
> >
> > Regards,
> > Andrej
> >
------------------------------------------
9fans: 9fans
Permalink: https://9fans.topicbox.com/groups/9fans/Tfa6823048ad90a21-M2b6a9ca6ba8b315c113a43e9
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next prev parent reply other threads:[~2022-06-17 16:11 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-17 9:37 andrey100100100
2022-06-17 13:46 ` Thaddeus Woskowiak
2022-06-17 14:11 ` Jacob Moody
2022-06-17 14:39 ` Thaddeus Woskowiak
2022-06-17 15:06 ` andrey100100100
2022-06-17 16:08 ` Skip Tavakkolian
2022-06-17 16:11 ` Skip Tavakkolian [this message]
2022-06-17 16:16 ` Skip Tavakkolian
2022-06-17 17:42 ` adr
2022-06-17 16:11 ` Jacob Moody
2022-06-17 18:48 ` andrey100100100
2022-06-17 19:28 ` Jacob Moody
2022-06-17 21:15 ` adr
2022-06-18 6:40 ` andrey100100100
2022-06-18 8:37 ` adr
2022-06-18 9:22 ` adr
2022-06-18 12:53 ` Jacob Moody
2022-06-18 22:03 ` andrey100100100
2022-06-19 5:54 ` adr
2022-06-19 6:13 ` Jacob Moody
2022-06-18 22:22 ` andrey100100100
2022-06-18 16:57 ` andrey100100100
2022-06-19 2:40 ` adr
2022-06-19 5:01 ` adr
2022-06-19 8:52 ` andrey100100100
2022-06-19 10:32 ` adr
2022-06-19 11:40 ` andrey100100100
2022-06-19 12:01 ` andrey100100100
2022-06-19 15:10 ` andrey100100100
2022-06-19 16:41 ` adr
2022-06-19 21:22 ` andrey100100100
2022-06-19 21:26 ` andrey100100100
2022-06-20 4:41 ` adr
2022-06-20 5:39 ` andrey100100100
2022-06-20 5:59 ` adr
2022-06-20 15:56 ` andrey100100100
2022-06-20 22:29 ` Skip Tavakkolian
2022-06-21 7:07 ` andrey100100100
2022-06-21 11:26 ` adr
2022-06-21 13:03 ` andrey100100100
2022-06-21 13:22 ` adr
2022-06-28 15:28 ` adr
2022-06-28 16:43 ` ori
2022-06-28 18:19 ` adr
2022-06-28 18:28 ` adr
2022-06-28 19:09 ` andrey100100100
2022-06-28 19:42 ` adr
2022-06-29 13:14 ` adr
2022-06-21 13:47 ` andrey100100100
2022-06-21 7:22 ` adr
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