Hello! On Thu, Oct 07, 2021 at 03:16:37PM +0000, Eran Kornblau wrote:
> > -----Original Message----- > > From: nginx-devel <nginx-devel-boun...@nginx.org> On Behalf Of Maxim Dounin > > Sent: Thursday, 7 October 2021 16:07 > > To: nginx-devel@nginx.org > > Subject: Re: Sending a notification to the main nginx thread > > > > Hello! > > > > To re-iterate: inside a "side thread" you are not allowed to call any > > non-thread-safe libc functions. It is reasonable to assume this excludes > > all 3rd party libraries with their own even loops. > > This is a valid point. > > I checked it out, with the specific build options I'm using on Linux, these > are the non-thread-safe libc functions used by nginx - > (list of all non-thread-safe functions taken from > https://man7.org/linux/man-pages/man7/pthreads.7.html, assuming POSIX.1-2008) > - > > $ (objdump -T /usr/local/nginx/sbin/nginx | grep GLIBC | awk '{print $NF}' ; > cat /tmp/libc-non-thread-safe) | sort | uniq -c | grep -vw 1 > 2 dlerror > 2 getenv > 2 getgrnam > 2 getpwnam > 2 localtime > 2 strerror > > First 4 functions are called only early on nginx startup from what I see, so > not relevant in this context. > That leaves me only with strerror & localtime. > > I verified these 2 functions are not used by the specific library I'm linking > against. > So, assuming I don't use any nginx functions on the side thread (other than > ngx_notify), it feels quite safe to me... In no particular order: - Assuming nginx uses only POSIX functions is wrong, it does use platform-specific functions and various portable functions not specified by POSIX, such as - The above objdump results look incorrect: for example, nginx certainly uses readdir(), which is in the POSIX non-thread-safe list, but not in your list. - There are other libraries nginx uses, which makes the problem much worse. If you insist on using threads in your module - you are free to do so, you were warned and it's your choice. -- Maxim Dounin http://mdounin.ru/ _______________________________________________ nginx-devel mailing list nginx-devel@nginx.org http://mailman.nginx.org/mailman/listinfo/nginx-devel
