From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753594AbZIPOwJ (ORCPT ); Wed, 16 Sep 2009 10:52:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751440AbZIPOwI (ORCPT ); Wed, 16 Sep 2009 10:52:08 -0400 Received: from ox1.aei.mpg.de ([194.94.224.6]:55016 "EHLO ox1.aei.mpg.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751229AbZIPOwH (ORCPT ); Wed, 16 Sep 2009 10:52:07 -0400 X-Greylist: delayed 1818 seconds by postgrey-1.27 at vger.kernel.org; Wed, 16 Sep 2009 10:52:07 EDT Date: Wed, 16 Sep 2009 16:21:37 +0200 From: Henning Fehrmann To: linux-kernel@vger.kernel.org Subject: gzip sleeps until 'strace'ing the process Message-ID: <20090916142137.GA25033@gretchen.aei.mpg.de> MIME-Version: 1.0 User-Agent: Mutt/1.5.18 (2008-05-17) X-MIMETrack: Itemize by SMTP Server on intranet/aei-hannover(Release 8.5HF224 | March 30, 2009) at 09/16/2009 16:21:38, Serialize by Router on intranet/aei-hannover(Release 8.5HF224 | March 30, 2009) at 09/16/2009 16:21:48, Serialize complete at 09/16/2009 16:21:48 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-PMX-Version: 5.5.5.374460, Antispam-Engine: 2.7.1.369594, Antispam-Data: 2009.9.16.140618 X-PerlMx-Spam: Gauge=IIIIIIII, Probability=8%, Report=' BODY_SIZE_2000_2999 0, BODY_SIZE_5000_LESS 0, BODY_SIZE_7000_LESS 0, TO_NO_NAME 0, __C230066_P5 0, __CD 0, __CT 0, __CT_TEXT_PLAIN 0, __FRAUD_419_CONTACT_NAME 0, __HAS_MSGID 0, __MIME_TEXT_ONLY 0, __MIME_VERSION 0, __RUS_OBFU_PHONE 0, __SANE_MSGID 0, __STOCK_PHRASE_24 0, __TO_MALFORMED_2 0, __USER_AGENT 0' Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, If you have some hints, please put me in the CC. We launched a job which forks a gzip -cd which is basically zcat. This process is accessing a file within a NFS mounted directory: # ps aux|grep gzip user 32078 0.0 0.0 4140 552 pts/0 S+ 15:06 0:00 gzip -cd -f file_in_NFS_mounted_directory The file is properly ziped. The process is in the sleep state - also the file can be accessed. If I 'strace' it the process finishes successfully. # strace -p 32078 Process 32078 attached - interrupt to quit write(1, "e-010 5.5565\n121.951418712 2.2249"..., 24578) = 24578 write(1, "3 -0.3036801 -3.1699e-011 5.30998"..., 32768) = 32768 write(1, "2015e-010 5.5565\n121.9529017461 2"..., 32768) = 32768 write(1, "\n121.9543512274 0.166872 -0.13840"..., 32768) = 32768 write(1, "-011 5.5565\n121.9558745249 5.2519"..., 32768) = 32768 write(1, "08331213 -4.2015e-010 5.80302\n121"..., 32768) = 32768 write(1, "1.9587130924 4.603975 -0.2485881 "..., 32768) = 32768 read(8, "\361\234a\325\305\3161\373x\307\324\312\240+\307\354\211Y\357cH\234\360\362\315\235NV\310O\\\212\236"..., 32768) = 14630 read(8, ""..., 18138) = 0 write(1, "600686259 5.408658 -0.5240481 -1."..., 32768) = 32768 write(1, "5.707316 -0.3587721 -4.2015e-010 "..., 32768) = 32768 write(1, "1.9627260083 5.766155 -0.3587721 "..., 30733) = 30733 close(8) = 0 exit_group(0) = ? Process 32078 detached I found it puzzling since strace should not have an influence on the state of a process. In the /proc directory I found the follwing: /proc/32078# cat status Name: gzip State: S (sleeping) Tgid: 32078 Pid: 32078 PPid: 31592 TracerPid: 0 Uid: 5059 5059 5059 5059 Gid: 5000 5000 5000 5000 FDSize: 256 Groups: 5000 5001 5002 VmPeak: 4140 kB VmSize: 4140 kB VmLck: 0 kB VmHWM: 552 kB VmRSS: 552 kB VmData: 492 kB VmStk: 84 kB VmExe: 52 kB VmLib: 1432 kB VmPTE: 32 kB Threads: 1 SigQ: 0/68608 SigPnd: 0000000000000000 ShdPnd: 0000000000000000 SigBlk: 0000000000000000 SigIgn: 0000000001300001 SigCgt: 0000000000805002 CapInh: 0000000000000000 CapPrm: 0000000000000000 CapEff: 0000000000000000 CapBnd: fffffffffffffeff voluntary_ctxt_switches: 55 nonvoluntary_ctxt_switches: 1 Do you have any idea? Cheers, Henning Fehrmann