Subject: Re: bug#14174: BUG REP: tee takes an annoyingly long time in some system.

From: Bernhard Voelker <[email-masked]>
Date: Thu, 11 Apr 2013 11:20:52 +0200

tag 14174 + moreinfo
close 14174
thanks

On 04/10/2013 11:48 AM, Gao, Jie (Kyrie, HPIT-DS-CDC) wrote:
> Hello sir,
> 
> Not sure if it is tee's problem. Tee works well in my workstation, but it will take
> a long time on cluster. See the example below. Could you if possible show me the
> reason why tee spends so long time while it is working on cluster?

Thank you for the report.
However, you can imagine that we have problems to reproduce this issue.

First of all, what do you mean by "is working on cluster"?

> 2.     With tee @ 1 minute 46 seconds:
> /home/sqdev16> time echo '
>> SET TRANSACTION ISOLATION LEVEL READ COMMITTED, READ WRITE, NO ROLLBACK OFF, MULTI COMMIT ON;
>> DELETE WITH MULTI COMMIT FROM manageability.instance_repository.problem_instance_table
>>   WHERE (gen_ts_lct) < ((CURRENT_TIMESTAMP) - CAST(CAST(0 AS INTEGER)  AS INTERVAL HOUR(2))); ' | sqlci | tee -a junk
>>>>>
> --- SQL operation complete.
>>> +>
> --- 0 row(s) deleted.
>>>
> 
> End of MXCI Session
> 
> real    1m45.969s
> user    0m0.180s
> sys     0m0.093s

What's the output of sqlci? Can you redirect it to a file and use that
as input for tee? Does that make a difference?
  ... | sqlci > file
  cat file | time tee -a junk

Can you provide strace output with timing information?
  ... | strace -tt tee -a junk

Another possibility: writing to 'junk' may somehow be blocked during
that run. Are there such timing difference between
   ... | sqlci > /dev/null
   ... | sqlci > junk2              # a new file / truncating
   ... | sqlci >> junk
   ... | sqlci > /tmp/junk          # i.e. a local file system
   ... | sqlci | tee /dev/null
   ... | sqlci | tee -a /tmp/junk   # i.e. a local file system
?

And finally, what version of tee are you using ("tee --version")?
Is it self-compiled or did it come with your distribution (which may
have added patches on top of the upstream version)?

Have a nice day,
Berny