Please add this bug to my sponsor requests:
BUG ID: 6920072
BUG Synopsis: ksh93 tail -f, with unconditional .25s sleep and line
parsing, about 37x slower than cat

2009/12/9 ????? ???????????? <olga.kryzhanovska at gmail.com>:
> This is a request for sponsors for fixing the following list of bugs:
>
> BUG ID: 6904557
> BUG Synopsis: wc no longer counts number of bytes correctly
>
> BUG ID:  6904575
> BUG Synopsis: cut -d with multibyte character no longer works
>
> BUG ID: 6904597
> BUG Synopsis: paste -d no longer works with multibyte characters
>
> BUG ID:  6904780
> BUG Synopsis: usr/bin/chksum changed output in snv_128
>
> BUG ID: 6904870
> BUG Synopsis: uniq -s does not skip multibyte characters correctly
>
> BUG ID: 6904878
> BUG Synopsis: join -t no longer works with multibyte char separator
>
>
> The same patch will fix the the P1 STOPPER bug:
> BUG ID: 6900314
> BUG Synopsis: (while true ; do true | true ; done) hang in ioctl() with 
> SIGTTOU
>
>
> Name: Olga Kryzhanovska
> Opensolaris user name: fleyta
> SCA ID: #OS0402
> --
>      ,   _                                    _   ,
>     { \/`o;====-    Olga Kryzhanovska   -====;o`\/ }
> .----'-/`-/     olga.kryzhanovska at gmail.com   \-`\-'----.
>  `'-..-| /     Solaris/BSD//C/C++ programmer   \ |-..-'`
>      /\/\                                     /\/\
>      `--`                                      `--`
>





---------- Forwarded message ----------
From:  <bugmail-sen...@sun.com>
Date: Tue, Jan 26, 2010 at 8:21 AM
Subject: [ksh93-integration-discuss] CR 6920072 Updated, P3
utility/text ksh93 tail -f, with unconditional .25s sleep and line
parsing, about 37x slower than cat
To:


*Synopsis*: ksh93 tail -f, with unconditional .25s sleep and line
parsing, about 37x slower than cat

CR 6920072 changed on Jan 26 2010 by <User 1-5Q-1267>

=== Field ============ === New Value ============= === Old Value =============

See Also               6790507
====================== =========================== ===========================


*Change Request ID*: 6920072

*Synopsis*: ksh93 tail -f, with unconditional .25s sleep and line
parsing, about 37x slower than cat

 Product: solaris
 Category: utility
 Subcategory: text
 Type: Defect
 Subtype:
 Status: 1-Dispatched
 Substatus:
 Priority: 3-Medium
 Introduced In Release:
 Introduced In Build:
 Responsible Engineer:
 Keywords:

=== *Description* ============================================================
Running tail -f on a nightly.log during a build on an Opensolaris
snv_126 machine,
I noticed that the tail was running long after the build had
completed.  The first
time I killed it; the second time I decided to let it run.  *26
minutes* after the
build completed, it finally completed (the entire build had only taken
28 minutes).

Now, this was across an ssh connection from EGO02 to MPK17, but I took the same
log file and did several tests:

tail -f: 26:XX
nfs cp:  00:29
scp:     00:29
scp -C:  00:36
cat:     00:42

That's quite a difference.

Trussing the command, I see that it's ksh93, and that ksh is apparently reading
line-chunked things of approximately 8K, and writing line-chunked blocks to the
output, and unconditionally delaying .25s between each stat/read/write call.
That latter, in particular, seems to be the biggest problem, and seems
ill-advised;
if there's to be a delay, it seems like "stat, and if no change sleep and then
stat again" would be a lot more efficient.

Also, for -f, I don't see why there's any point in doing the
line-oriented calls;
original tail didn't, and I can't imagine it's a win.

*** (#1 of 1): 2010-01-26 04:51:29 GMT+00:00 <User 1-5Q-12546>


=== *Public Comments* ========================================================

=== *Workaround* =============================================================

=== *Additional Details* =====================================================
       Targeted Release:
       Commit To Fix In Build:
       Fixed In Build:
       Integrated In Build:
       Verified In Build:
 See Also: 6790507
 Duplicate of:
 Hooks:
       Hook1:
       Hook2:
       Hook3:
       Hook4:
       Hook5:
       Hook6:
 Program Management:
 Root Cause:
 Fix Affects Documentation: No
 Fix Affects Localization: No

=== *History* ================================================================
       Date Submitted: 2010-01-26 04:51:29 GMT+00:00
       Submitted By: <User 1-5Q-12546>

       Status Changed    Date Updated                  Updated By


=== *Service Request* ========================================================
       Impact: Significant
       Functionality: Secondary
       Severity: 3
       Product Name: solaris
       Product Release: solaris_nevada
       Product Build:
       Operating System: snv_126
       Hardware: generic
       Submitted Date: 2010-01-26 04:51:30 GMT+00:00


=== *Multiple Release (MR) Cluster* - 0 ======================================

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-- 
      ,   _                                    _   ,
     { \/`o;====-    Olga Kryzhanovska   -====;o`\/ }
.----'-/`-/     olga.kryzhanovska at gmail.com   \-`\-'----.
 `'-..-| /     Solaris/BSD//C/C++ programmer   \ |-..-'`
      /\/\                                     /\/\
      `--`                                      `--`

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