/usr/bin/script eating 100% cpu with portupgrade and xargs

[Ronald Klop]

On Sun, 18 Sep 2011 07:39:01 +0200, Jeremy Chadwick  
<freebsd at jdc.parodius.com> wrote:

> On Sun, Sep 18, 2011 at 12:54:13AM -0400, Jason Hellenthal wrote:
>> On Sun, Sep 18, 2011 at 01:49:15AM +0200, Ronald Klop wrote:
>> > Hi,
>> >
>> > I'm running portupgrade in screen to update all the ports for
>> > 9-BETA2/9-CURRENT on amd64. While doing this script eats 100% cpu.
>> > Because portupgrade -fa crashed I'm running this command to update the
>> > remaining non-updates ports.
>> > find /var/db/pkg -name +DESC -mtime +2 |cut -d / -f 5 | xargs time  
>> nice -n
>> > 20 portupgrade -f
>> >
>> > The output of truss -p `pgrep script` is this:
>> > clock_gettime(13,{1316301104.000000000 })        = 0 (0x0)
>> > select(5,{0 4},0x0,0x0,{30.000000 })             = 1 (0x1)
>> > read(0,0x7fffffffcdf0,1024)                      = 0 (0x0)
>> > write(4,0x7fffffffcdf0,0)                        = 0 (0x0)
>> > clock_gettime(13,{1316301104.000000000 })        = 0 (0x0)
>> > select(5,{0 4},0x0,0x0,{30.000000 })             = 1 (0x1)
>> > read(0,0x7fffffffcdf0,1024)                      = 0 (0x0)
>> > write(4,0x7fffffffcdf0,0)                        = 0 (0x0)
>> > clock_gettime(13,{1316301104.000000000 })        = 0 (0x0)
>> > select(5,{0 4},0x0,0x0,{30.000000 })             = 1 (0x1)
>> > read(0,0x7fffffffcdf0,1024)                      = 0 (0x0)
>> > write(4,0x7fffffffcdf0,0)                        = 0 (0x0)
>> > clock_gettime(13,{1316301104.000000000 })        = 0 (0x0)
>> > select(5,{0 4},0x0,0x0,{30.000000 })             = 1 (0x1)
>> > read(0,0x7fffffffcdf0,1024)                      = 0 (0x0)
>> > write(4,0x7fffffffcdf0,0)                        = 0 (0x0)
>> >
>> > So it is really fast in reading and writing 0 bytes most of the time.
>> >
>> > I also found  
>> http://web.archiveorange.com/archive/v/6ETvLvjo60Gj9geAUAb6
>> > and I think I am better of by rewriting my command so stdin/stdout is
>> > still the terminal. Although the link is a couple of years old.
>> >
>> > Is this known? Can somebody explain me why my xargs command is not  
>> working
>> > well?
>> >
>>
>> Are you absolutely sure that its script(1) causing this ? 100% CPU usage
>> has been a known side effect of screen(1) for quite some time. Rebuild
>> it and try again.
>
> Jason's referring to this, I believe:
> http://www.freebsd.org/cgi/cvsweb.cgi/ports/sysutils/screen/Makefile#rev1.55
>
> To clarify the what the commit message means: it does not mean "when the
> package is installed the installation takes up 100% CPU".  It means
> "once the package is installed and screen is used, screen takes up 100%
> CPU".  I know because I've seen this behaviour in the past (one of the
> many, many reasons I build ports from source).
>
> However:
> http://www.freebsd.org/cgi/cvsweb.cgi/ports/sysutils/screen/Makefile#rev1.78
>
> So: If a binary package is being installed through your above
> portupgrade command, and you're seeing this problem, then it sounds to
> me like commit revision 1.78 is a regression and NO_PACKAGE should be
> put back into place + packages removed from all mirrors.
>
> There are many reasons to not use GNU screen at all, or if you must have
> something like it, use tmux.  I recently had to provide an analysis of
> how GNU screen destroys one's terminal[1]; so if the above problem turns
> out to be caused by GNU screen as well, I'll just add it to my
> ever-growing list of reasons the software should be nuked from orbit.
>
> Otherwise, if this turns out to be a problem with portupgrade (which you
> found some evidence supporting such), then the solution is simple: stop
> using portupgrade, use portmaster (if it lacks things you need ask Doug
> Barton, he's incredibly receptive to adding new features/fixing things).
> Two databases that aren't compatible, ruby shims, and other crap = not
> worth it.  Think the database ordeal is long over with/fixed/whatever?
> It isn't[2].
>
> [1]:  
> http://lists.freebsd.org/pipermail/freebsd-stable/2011-June/063052.html
> [2]:  
> http://www.dslreports.com/forum/r26304856-FreeBSD-defining-portmaster-alias
>

I have a repeatable test. Run top in a window and this command in another.
$ echo test | script /tmp/script-test sleep 1000
Script started, output file is /tmp/script-test
test

   PID USERNAME       THR PRI NICE   SIZE    RES STATE   C   TIME    CPU  
COMMAND
29656 ronald           1 103    0 12324K  1244K CPU4    4   1:03 100.00%  
script

So it has nothing to do with portupgrade or screen. The output of truss  
-p29656 is the same as posted previously.

Ronald.