Re: Fix for "q" with psql display paging dumps out of psql - Mailing list pgsql-hackers

You will be glad to know that 8.0 will use a different implementation
for thread handling of SIGPIPE, though your asynchronous handling of
SIGPIPE will still cause problems.

---------------------------------------------------------------------------

Jim Seymour wrote:
> Hi,
> 
> I'm kind of wondering if anybody on the dev team noticed this and
> what, if anything, they planned to do with it?
> 
> Jim
> 
> jseymour@linxnet.com (Jim Seymour) wrote:
> > 
> > 
> > Hi,
> > 
> > Environment:
> > 
> >     SunOS 5.7 Generic_106541-29 sun4u sparc SUNW,UltraSPARC-IIi-Engine
> >     Postgresql-7.4.6
> >         Build config: --with-java --enable-thread-safety
> >     gcc version 3.3.1
> >     less-381
> >     readline-4.3
> > 
> >     $ echo $PAGER
> >     /usr/local/bin/less
> >     $ echo $LESS
> >     -e
> > 
> > I recently upgraded from 7.4.2 to 7.4.6 and ran into an annoying
> > problem.  Thereafter, most times, "q"uitting out of paged display
> > output would dump me straight out of psql if the query result was
> > sufficiently large.
> > 
> > A bit of debugging revealed psql receiving a SIGPIPE to be the
> > problem.
> > 
> > Building pgsql w/o --enable-thread-safety eliminated the problem.
> > 
> > It looks like the culprit is asynchronous SIGPIPE signals under Solaris
> > 7 when using thread-safe libraries.  Here's a reference:
> > <http://www.lambdacs.com/cpt/FAQ.html#Q339>.
> > 
> > I do not know if Solaris 8 and beyond behave this way.  (Apparently
> > async SIGPIPE is not POSIX-compliant, so one hopes Sun has fixed this
> > broken behaviour.)
> > 
> > Here's a fix that's simple, effective and doesn't hurt anything else:
> > 
> > ------------------------- begin included text --------------------------
> > *** src/bin/psql/print.c-orig   Wed Nov 17 08:04:47 2004
> > --- src/bin/psql/print.c        Sat Nov 20 10:43:22 2004
> > ***************
> > *** 1119,1124 ****
> > --- 1119,1128 ----
> >         {
> >                 pclose(output);
> >   #ifndef WIN32
> > +               /* The SIG_IGN is to compensate for broken Solaris 7
> > +                * (async) SIGPIPE handling with --enable-thread-safety
> > +                */
> > +               pqsignal(SIGPIPE, SIG_IGN);
> >                 pqsignal(SIGPIPE, SIG_DFL);
> >   #endif
> >         }
> > -------------------------- end included text ---------------------------
> > 
> > Thanks to Andrew, over at SuperNews, for the idea.
> > 
> > Regards,
> > Jim
> > 
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