call ngx_localtime may cause deadlock?

[Igor Sysoev]

On Thu, Mar 04, 2010 at 07:49:57PM +0300, Maxim Dounin wrote:

> Hello!
> 
> On Thu, Mar 04, 2010 at 10:20:29AM -0500, georgexsh wrote:
> 
> > Igor Sysoev Wrote:
> > -------------------------------------------------------
> > 
> > > Here is third-party module which probably uses
> > > threads:
> > > 
> > > #11 0x08088c9f in ngx_foo_time_str (r=0x9dcdc28,
> > > time_str=0xbfe18450, t=-4) at
> > > ./ngx_foo_module//uti.c:111
> > > #12 0x08087d1a in ngx_http_foo_record
> > > (r=0x9dcdc28, request_arg=0x9dcddb0) at
> > > ./ngx_foo_module//foo.c:124
> > > #13 0x0808788c in ngx_http_foo_handler
> > > (r=0x9dcdc28) at
> > > ./ngx_foo_module//ngx_http_foo_module.c:74
> > > 
> > 
> > 
> > No, ngx_foo_module/* is my module which does't use threads ethier.
> > 
> > ref:
> > http://blogs.inxsasia.com/hiran/2009/07/stupid-futex-and-glibc.html
> > http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=301511
> 
> Ok, second link suggest that recent glibc uses futex even when 
> there are no threads in application.
> 
> This isn't really relevant though as underlying problem is in 
> nginx and should be fixed anyway.  Only async-signal-safe 
> functions may be used in signal handlers, anything else leads to 
> undefined behaviour.

Strickly speaking the generic signal handler calls localtime/_r() too:
    ngx_time_update(0, 0);

And if timer_resolution bug can be fixed easy, nevertheless, I do not
know how to log local time in singal handler without localtime().


-- 
Igor Sysoev
http://sysoev.ru/en/