bugGNU Parallel - build and execute command lines from standard input in parallel - Bugs: bug #36595, silent loss of input with --pipe...

 
 

bug #36595: silent loss of input with --pipe and --sshlogin

Submitted by:  None
Submitted on:  Tue 05 Jun 2012 08:26:00 PM UTC  
 
Category: NoneSeverity: 4 - Important
Item Group: NoneStatus: Confirmed
Privacy: PublicAssigned to: Ole Tange <tange>
Open/Closed: Closed

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Thu 07 Jun 2012 11:10:47 PM UTC, comment #3:

Fixed in [38ccd3f]

Ole Tange <tange>
Project AdministratorIn charge of this item.
Thu 07 Jun 2012 09:40:13 PM UTC, comment #2:

This is crazy. Clearly needs to be submitted to perl experts.

seq 10000| xargs | the_below

Fails:

#!/usr/bin/perl

open (S, "ssh eos true & ssh eos true & |");
my $s = <S>;
while(<STDIN>) {
print;
}

Works:

#!/usr/bin/perl

open (S, "ssh eos true & ssh eos true & |");
#my $s = <S>;
while(<STDIN>) {
print;
}

Ole Tange <tange>
Project AdministratorIn charge of this item.
Thu 07 Jun 2012 09:13:32 PM UTC, comment #1:

The problem is here:

open (SIMUL, "($cmd)|grep simultaneouslogin | wc -l|") or
::die_bug("simultaneouslogin");
# STDIN is OK here
my $ssh_limit = <SIMUL>;
# STDIN is f*cked here
close SIMUL;

How on earth can <SIMUL> screw up <STDIN>?!

Ole Tange <tange>
Project AdministratorIn charge of this item.
Tue 05 Jun 2012 08:26:00 PM UTC, original submission:

Under certain circumstances, the combination of --pipe and --sshlogin silently loses input. In particular, on several releases of RHEL5 (5.2, 5.6, 5.8), I can consistently produce the following results:

$ parallel --version | head -n 1
GNU parallel 20120522

$ echo hi > hi
$ parallel --pipe --sshlogin 10/localhost cat < hi
(no output)

$ echo hi | parallel --pipe --sshlogin 10/localhost cat
hi

$ parallel --pipe --sshlogin 9/localhost cat
hi

$ seq 10000 | parallel --pipe --sshlogin 10/localhost cat | wc
1040 1040 4096

I could not produce these problems on Debian testing, and increasing MaxStartups in sshd_config does not affect the 10 login breaking point.

Anonymous

 

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  • -unavailable- added by tange (Updated the item)
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    Follow 4 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Thu 07 Jun 2012 11:10:47 PM UTCtangeOpen/ClosedOpen=>Closed
    Thu 07 Jun 2012 07:37:09 PM UTCtangeSeverity3 - Normal=>4 - Important
      StatusNone=>Confirmed
      Assigned toNone=>tange

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