Date: Fri, 28 Jan 2011 12:47:42 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: Sergey Kandaurov <pluknet@gmail.com> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: unbounded sleep on [fifoow] while open a named pipe: is it a feature? Message-ID: <20110128104742.GU2518@deviant.kiev.zoral.com.ua> In-Reply-To: <AANLkTinQRyEABOHfMRMJMecMKtAixzf_yRTizCJT5XsO@mail.gmail.com> References: <AANLkTinQRyEABOHfMRMJMecMKtAixzf_yRTizCJT5XsO@mail.gmail.com>
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--YVVuqqmpr1hAxwPf Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jan 28, 2011 at 12:43:38PM +0300, Sergey Kandaurov wrote: > Hi. >=20 > That's FreeBSD 8.1-RELEASE i386 (w/o debug). >=20 > It's observed for bash processes which end up in unbounded sleep > in [fifoow] wchan while executing the next script: >=20 > %%% > #!/usr/local/bin/bash >=20 > LOG_FACILITY=3D"local7.notice" > LOG_TOPIC_OUT=3D"$TAG-output[$$]" > LOG_TOPIC_ERR=3D"$TAG-error[$$]" >=20 > cd $WORK_DIR >=20 > exec > >(logger -p "$LOG_FACILITY" -t "$LOG_TOPIC_OUT" ) > exec 2> >(logger -p "$LOG_FACILITY" -t "$LOG_TOPIC_ERR" ) > eval exec $1 > %%% >=20 > It's used to call $1 and redirect its stdout and stderr streams > to different files. Bash implements this functionality by creating > on every execution a new named pipe stored at /var/tmp/ directory. > This script is used to run periodically from cron(8). Note, that bash > has a misfeature to not delete those named pipes. With a high creation > frequency of named pipes (several per minute) it eventually ends > up with a large number [~137000] of existing named pipes, when it > was found that a number [~44] of bash processes sleep on [fifoow], > which is guessed to be likely caused by the number of fifo pipes created. >=20 > For example, this one sleeps for about 1.5 days: > 1001 78809 78803 0 50 0 4564 1952 fifoow Is ?? 0:00.00 > /usr/local/bin/bash ./logger_wrapper.sh ./sync_overlords.pl >=20 > # procstat -f 78809 > [...] > 78809 bash 1 f - -w------ 1 0 - /var/tmp/sh-np-[= random] > [...] >=20 > # procstat -kk 78809 > PID TID COMM TDNAME KSTACK > 78809 100733 bash - mi_switch+0x12a > sleepq_switch+0xcc sleepq_catch_signals+0x5b sleepq_wait_sig+0x18 > _sleep+0x28c fifo_open+0x718 VOP_OPEN_APV+0x42 vn_open_cred+0x52b > vn_open+0x3b kern_openat+0x125 kern_open+0x35 open+0x30 syscall+0x2d3 > Xint0x80_syscall+0x20 fifoow means that pipe is opened for writing while no readers exists. --YVVuqqmpr1hAxwPf Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAk1Cns0ACgkQC3+MBN1Mb4gHgQCeInXCnHD9Yruo73pF2Ax8lal7 +08An3udZhKNJPb+LuGhWjkjK9bKXnF1 =JKSh -----END PGP SIGNATURE----- --YVVuqqmpr1hAxwPf--
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