RE: builtin bash echo failing - errno EINTR on multi-CPU machine

[Philippe Champagne]

I was able to reproduce the problem with a smaller bash script.

Only require that file

I notice that if I remove either the "read tag val ... " line (and artificially set tag and val to some values)

or if I remove the if statement following it, then I don't get the echo error (ie: echo returning failure).

 

#!/bin/bash

let i=0;

 

while true; do
                let i=$i+1
                line="filename: aajjj"

 

                read tag val < <(echo "$line")

 

                if [ "$tag" = "filename" ]; then
                    fname="$val"
                elif [ "$tag" = "size" ]; then
                    nbytes="$val"
                fi

 

                # format the output
                if [ ! -z  "$tag" ] && [ ! -z "$val" ]; then
                        echo -n "| $tag: $val" || {
echo $?
echo "echo1 failed"
exit 1
}
                fi
                if [ "$i" -eq 10 ]; then
                    echo " Done " || {
echo " echo2 failed "
exit 1
}
                    exit 0;
                fi
done
exit 0

 

 

-----Original Message-----
Subject: builtin bash echo failing - errno EINTR on multi-CPU machine

Hi

 

I have a condition where I get about 5% failures of echo in bash.

The failure rate varies depending on the machine but easier to get on multiprocessor machine. Actually, so far I was not able to reproduce it on a single CPU machine... (SMP related?)

I'm running Linux 2.4.20 and GNU bash, version 2.05a.0(1)-release (i686-pc-linux-gnu)
glibc version is 2.2.5 but I tried on another machine that uses glibc 2.3.2 and all had the problem (all that have dual CPU or more)

 

With some debug code, I found out errno is set to EINTR when we get the error.

This errno is set after a call to printf in the bash builtin echo C source code.

 

I was hoping you could help me figure out what's going on here.

 

Following are the 3 files required

mytest.sh is the actual bash file with the failing echo

test.pkg is a file mytest.sh uses

trun.sh is a little helper to run it many times.

 

Note: the "echo1 failed" or "echo2 failed" are the 2 locations where we hit the problems.

(although as you can see, we haven't check the exit code from all echo)

 

Any help will be appreciated - thx

 

------------------mytest.sh

#!/bin/bash

 

ifs=$IFS
IFS=$(echo -ne '\t\r\n')

 

while read sh_line
do
        #echo "sh_line: [$sh_line]"
        if [ -z $sh_line ]
        then
                ## start reading files
                first_line=0
                while read line junk
                do
                        IFS=' :'
                        read tag val < <(echo "$line")

 

                if [ "$tag" = "filename" ]; then
                    fname="$val"
                elif [ "$tag" = "size" ]; then
                    nbytes="$val"
                elif [ -z $tag ] && [ -z $val ]; then
                        echo " "
                fi

 

                # format the output
                if [ ! -z  "$tag" ] && [ ! -z "$val" ]; then
                        if [ $first_line -eq 1 ]; then
                                echo -n "| $tag: $val" || {
echo $?
echo "echo1 failed"
exit 1
}
                        else
                                echo -n "$tag: $val" || {
echo $?
echo "echo2 failed"
exit 1
}
                        first_line=1
                        fi
                fi

 

                # go back to reading one line at a time.
                IFS=$(echo -ne '\t\r\n')
                done
        fi
done < test.pkg
exit 0
------------- end

 

-------test.pkg file needed by mytest.sh

name: something
description: A Simple Description
platform: PC
size: 14329

 

filename: flist.txt
filetype: txt
size: 143209
utc_date: 060220262004.17
char_count: 32672

 

-----------end

 

-------------  trun.sh

#!/bin/bash
#
#

 

echo "starting test"

 

let good=0;
let bad=0;

 

let i=0;

 

while true; do
        let i=$i+1
        if ./mytest.sh; then
                let good=$good+1
        else
                let bad=$bad+1
        fi
        if [ "$i" -eq 100 ]; then
                echo "SUCCESSFUL: $good" >> ./result.txt
                echo "FAIL CALLS: $bad"  >> ./result.txt
                let good=0;
                let bad=0;
                let i=0;
#               exit 0;
        fi
done
--------------- end