-------- Original Message --------
Subject: Re: Re : rt_printf with daemonized task (08-Okt-2009 14:19)
From: Gilles Chanteperdrix <[email protected]>
To: [email protected]
> Jan Kiszka wrote:
> > Gilles Chanteperdrix wrote:
> >> Jan Kiszka wrote:
> >>> Gilles Chanteperdrix wrote:
> >>>> [email protected] wrote:
> >>>>>>> int main( int arc, char *argv[] ) { int i;
> >>>>>>>
> >>>>>>> rt_print_auto_init(1);
> >>>>>>>
> >>>>>>> rt_printf("--------------- TEST RT-PRINTF 1 ------------\n");
> >>>>>>>
> >>>>>>> sleep(1);
> >>>>>>>
> >>>>>>> daemon(0,0);
> >>>>>>>
> >>>>>>> rt_print_auto_init(1);
> >>>>> Ok, understood, at least for the scenario where the rt_print feature
> >>>>> is initialised befor the fork/daemon call. What I don't understand
> >>>>> is, why it does not work if the rt_print feature is initialised after
> >>>>> the fork / daemon.
> >>>> From the way I understand your code, you never tried to initialize the
> >>>> rt_print feature only after the fork, your code initializes it both
> >>>> before and after.
> >>>>
> >>> There are two initializations: The base init done via __rt_print_init
> on
> >>> library loading and the one to be done per-thread via rt_print_init (or
> >>> on first rt_printf). That printer thread is initialized via the former
> >>> one. On fork, we do not need to re-run the full __rt_print_init
> >>> (variables and resources are cloned on fork), we just need to spawn
> >>> another printer thread.
> >> Unless I am wrong, rtdk also maintains a list of the thread buffers
> >> which need to be polled. After the fork, this list will be intact, but
> >> the threads to which belong the buffers will no longer exist. So, IMO,
> >> the fork handler should also free all these buffers and reset the list
> >> to the empty state.
> >
> > Famous last words: That should work without tweaking. A print_buffer
> > only contains data references, nothing that points to some uncloned thread.
>
> Ok. But you walk the list of print_buffers every time, and these
> print_buffers remain allocated in the child process. So, that is a kind
> of memory leak.
>
> >
> > Jan
> >
>
>
> --
> Gilles
>
Did change my test code in the meantime to :
#include <stdlib.h>
#include <stdio.h>
#include <native/task.h>
#include <native/timer.h>
#include <rtdk.h>
int main( int arc, char *argv[] )
{
int i;
daemon(0,1);
__rt_print_init();
rt_print_auto_init(1);
rt_printf("--------------- TEST RT-PRINTF ------------\n");
sleep(10);
return(0);
}
and everything works fine at first glance.
There is at least an output to syslog of the rt_printf message. I have
no idea if this creates an internal memory leak. For my application
it might be not a real problem, because the fork is done only once.
For application with several fork calls or a recursional fork calls it might be
not ok.
Oliver
To: [email protected]
[email protected]
Cc: [email protected]
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