Re: localtime() thread-safe or not?
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MarkMark wrote:
> localtime() C Runtime API is documented
> (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclib/html/_crt_localtime.asp)
> to return result in static memory, which, of course is
> not thread safe.
>
> However, indirect evidence
> (http://support.microsoft.com/default.aspx?scid=kb;en-us;104641)
> appears to suggest that localtime() actually uses Thread
> Local Store which makes it thread safe.
>
> So my question is -- is localtime() really thread safe or
> not?
It depends on your definition of thread safety. If by thread
safety you mean thread awareness, then yes, localtime(), and
other CRT fuinctions are thread aware. It promises to work
correctly being called from different threads (provided CRT
thread info is properly initialized).
However, if by thread safety you mean data access
sinchronization, too, then CRT functions will not guarantee
you that. It's just too expensive and most of the time
simply unnecessary to embed synchronization objects on all
CRT functions. If strcpy or memset will be called from
different threads simultaneously on the same buffer, then
data corruption is likely. In that sense, CRT functions are
not thread safe.
.
Relevant Pages
- Re: localtime() thread-safe or not?
(microsoft.public.vc.language) - Re: localtime() thread-safe or not?
... to return result in static memory, which, of course is not thread safe. ... indirect evidence appears to suggest that localtimeactually uses Thread Local Store which makes it thread safe. ... So my question is -- is localtime() really thread safe or not? ...
(microsoft.public.vc.language) - localtime in Solaris 9 is not thread safe?
... I'm using pthreadprogramming in Solaris 9 and find that localtime is ... not thread safe. ... Franklin ...
(comp.unix.solaris) |
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