Re: c++/5298: stream::write

[Ronald Van Iwaarden <vaniwaar at ca dot metsci dot com>]

The following reply was made to PR c++/5298; it has been noted by GNATS.

From: Ronald Van Iwaarden <vaniwaar@ca.metsci.com>
To: <paolo@gcc.gnu.org>,  <gcc-bugs@gcc.gnu.org>,  <gcc-prs@gcc.gnu.org>, 
     <nobody@gcc.gnu.org>,  <paolo@gcc.gnu.org>,  <ron@vaniwaarden.org>, 
     <vaniwaar@ca.metsci.com>,  <gcc-gnats@gcc.gnu.org>
Cc:  
Subject: Re: c++/5298: stream::write
Date: Tue, 8 Jan 2002 09:59:26 -0800 (PST)

 This solved the symptom I described but there is still some funkiness
 going on.  Now, I know what I am describing here is not well defined
 behavior but if take the following program an run it, it always gives
 the same output (up to the order of the lines).  That is, every line is
 printed correctly, but they may come in different orders.  However, if
 you redirect the output to a file, sometimes the output of lines gets
 merged.  I never noted this behavior on the 2.96 compiler...
 
 
 int main()
 {
   std::ios::sync_with_stdio(false);
   int pid= fork();
 
   if (pid){
     cout<<0<<"ARG CALLED: Kind ID = "<<1<<", Data = data "<<endl;
     cout<<2<<"ARG CALLED: Kind ID = "<<1<<", Data = data "
 	<< "p1 = "<<12<<", "<<"p2 = "<<34<<", "<<endl;
     cout<<4<<"ARG CALLED: Kind ID = "<<1<<", Data = data "
 	<< "p1 = "<<12<<", "<<"p2 = "<<34<<", "<<"p3 = "<<56<<", "
 	<<"p4 = "<<78<<", "<<endl;
     cout<<6<<"ARG CALLED: Kind ID = "<<0<<", Data = data "
 	<< "p1 = "<<12<<", "<<"p2 = "<<34<<", "<<"p3 = "<<56<<", "
 	<<"p4 = "<<78<<", "<<"p5 = "<<90<<", "<<"p6 = "<<12<<", "<<endl;
     cout<<8<<"ARG CALLED: Kind ID = "<<0<<", Data = data "
 	<< "p1 = "<<12<<", "<<"p2 = "<<34<<", "<<"p3 = "<<56<<", "
 	<<"p4 = "<<78<<", "<<"p5 = "<<90<<", "<<"p6 = "<<12<<", "
 	<<"p7 = "<<34<<", "<<"p8 = "<<56<<", "<<endl;
   }
   else{
     cout<<1<<"ARG CALLED: Kind ID = "<<1<<", Data = data "
 	<< "p1 = "<<12<<", "<<endl;
     cout<<3<<"ARG CALLED: Kind ID = "<<1<<", Data = data "
 	<< "p1 = "<<12<<", "<<"p2 = "<<34<<", "<<"p3 = "<<56<<", "
 	<<endl;
     cout<<5<<"ARG CALLED: Kind ID = "<<0<<", Data = data "
 	<< "p1 = "<<12<<", "<<"p2 = "<<34<<", "<<"p3 = "<<56<<", "
 	<<"p4 = "<<78<<", "<<"p5 = "<<90<<", "<<endl;
     cout<<7<<"ARG CALLED: Kind ID = "<<0<<", Data = data "
 	<< "p1 = "<<12<<", "<<"p2 = "<<34<<", "<<"p3 = "<<56<<", "
 	<<"p4 = "<<78<<", "<<"p5 = "<<90<<", "<<"p6 = "<<12<<", "
 	<<"p7 = "<<34<<", "<<endl;
   }
 }
 
 run "./a.out > ff; cat ff | sort" and, if run multiple times, you get
 different output.  Note that you get exactly the same output every time
 if you do "./a.out | sort".
 
 Hmmm.  Sorry for the sort of funky description and example...
 
 --Ron
 On 7 Jan 2002 paolo@gcc.gnu.org wrote:
 
 > Synopsis: stream::write
 >
 > Responsible-Changed-From-To: unassigned->paolo
 > Responsible-Changed-By: paolo
 > Responsible-Changed-When: Mon Jan  7 14:15:59 2002
 > Responsible-Changed-Why:
 >     Analyzed.
 > State-Changed-From-To: open->feedback
 > State-Changed-By: paolo
 > State-Changed-When: Mon Jan  7 14:15:59 2002
 > State-Changed-Why:
 >     Hi again Ron!
 >     This one should be easier to solve (I hope): could you
 >     please try adding a:
 >     std::ios::sync_with_stdio(false);
 >     at the beginning of your main?
 >     It works for me (gcc3.0.3 on i686-pc-linux-gnu).
 >
 >     Cheers,
 >     Paolo.
 >
 > http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5298
 >
 
 -- 
 --------------------------------------------------------------------------------
 Ronald Van Iwaarden - Metron Inc. (719)567-9873
 
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