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

[Jason Hellenthal]

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.
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