Re: [Boost-build] bjam bug invoking codeworker

Subject: Re: [Boost-build] bjam bug invoking codeworker
From: Vladimir Prus (ghost_at_[hidden])
Date: 2009-10-26 10:39:22

On Monday 26 October 2009 Fabien CHÊNE wrote:

> [...]
> >> bjam is stucked line 470:
> >>
> >> 455 if ( 0 < globs.timeout )
> >> 456 {
> >> 457     /* Force select() to timeout so we can terminate expired processes.
> >> 458     */
> >> 459     tv.tv_sec = select_timeout;
> >> 460     tv.tv_usec = 0;
> >> 461
> >> 462     /* select() will wait until: i/o on a descriptor, a signal, or we
> >> 463     * time out.
> >> 464     */
> >> 465     ret = select( fd_max + 1, &fds, 0, 0, &tv );
> >> 466  }
> >> 467  else
> >> 468  {
> >> 469      /* select() will wait until i/o on a descriptor or a signal. */
> >> 470      ret = select( fd_max + 1, &fds, 0, 0, 0 );
> >> 471 }
> >>
> >> Any ideas ?
> >> Can it be a bug in CodeWorker ?
> >
> > Not clear yet. When the hang happens, is there still a codeworker process?
> 
> Definitely.
> 
> > Can you attach to it with gdb, and get backtrace? Please check if it has
> > multiple threads -- using 'info thread' -- if so, use "thread apply all bt"
> > to get backtrace as opposed to regular "bt"
> 
> There is only one thread in codeworker, stucked on a tcsetattr call:
> 
> (gdb) bt
> #0  0x002ca7a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
> #1  0x00bbf400 in tcsetattr () from /lib/tls/libc.so.6
> #2  0x0808d4bf in initKeyboard () at CGRuntime.cpp:115
> #3  0x082258ca in Workspace (this=0xbff323d0) at Workspace.cpp:58
> #4  0x0808e595 in CodeWorker::CGRuntime::entryPoint (iNargs=4,
>     tsArgs=0xbff32564, executeFunction=0x0) at CGRuntime.cpp:383
> #5  0x08241c98 in main ()
> (gdb) f 2
> #2  0x0808d4bf in initKeyboard () at CGRuntime.cpp:115
> 115			tcsetattr(0, TCSANOW, &new_settings);
> (gdb) l
> 110			new_settings.c_lflag &= ~(ICANON | ECHO);
> 111			new_settings.c_iflag &= ~(ISTRIP | IGNCR | ICRNL | INLCR | IXOFF | IXON);
> 112			new_settings.c_cc[VMIN] = 0;
> 113			new_settings.c_cc[VTIME] = 0;
> 114	#ifndef CODEWORKER_GNU_READLINE
> 115			tcsetattr(0, TCSANOW, &new_settings);
> 116	#endif
> 117			signal(SIGINT, catch_sig);
> 118			signal(SIGHUP, catch_sig);
> 119			signal(SIGTERM, catch_sig);
> 
> (gdb) set print pretty on
> (gdb) p new_settings
> $2 = {
>   c_iflag = 0,
>   c_oflag = 1,
>   c_cflag = 191,
>   c_lflag = 35377,
>   c_line = 0 '\0',
>   c_cc = "\003\034\000\000\004\000\000\000\021\023\032\000\022\017\027\026",
> '\0' <repeats 15 times>,
>   c_ispeed = 15,
>   c_ospeed = 15
> }

If it's really stuck there, e.g. it remains there after "continue + Ctrl-C" in
GDB, it seems that tcsetattr for some reason hangs if stdin is not a terminal.
And when run by bjam, it's naturally not a terminal. I don't immediately
know why this should be a problem, I'll check.

- Volodya