System hang / extreme slowdown under MySQL
From: Murray Taylor (MTaylor_at_bytecraft.com.au)
Date: 09/29/05
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Date: Thu, 29 Sep 2005 09:28:28 +1000 To: <freebsd-hackers@freebsd.org>
We are using MySQL on a FreeBSD box for one of our systems
and recently after doing a number of application code changes to
support a new client the system experiecned what seemed to be
a total hang. It didnt crash per se, no log messages
were caught.... it just went mostly unresponsive.
The data base is accessed via a set of TCL, C and web apps.
The symptoms are no response to any of the programs, yet
things like switching virtual consoles etc work ok. But it is
not possible to login... one can type 'root', see the characters echoed,
press enter and get nothing..
If there is an open ssh session or open console session, one
could issue a single command, like 'ls', get the response, then say
issue a 'ps' and only get the header line.....
On one of the occasions as we fly in to reboot the box, one of the
users said that it _was working_ just V E R Y S L O W L Y....
like 3 web pages in 30 minutes.
We did find some unclosed database queries in the TCL code that
have been fixed, but based on a sysctl that 'seems to be significant'
we may not yet have found all our problems.
The sysctl that we have picked is the one printed below and in
particular
the crosspoint PV ENTRY: / USED value. this is slowly but consistently
increasing
on this box, yet remains stable on all other FreeBSD boxes.
THE QUESTIONs are:
Is this the correct sysctl to be monitoring?
Is there a good description of the sysctl identified re relevance
of the numbers to the actual system condition?
Does anyone have any other ideas of things to look for that may
causing the hangs?
The system is
FreeBSD svmysql1.dand07.au.bytecraft.au.com 4.10-RELEASE-p7 FreeBSD
4.10-RELEASE-p7 #3: Thu Apr 14 15:34:37 EST 2005
Both the old system (Mysql 3.23) and the current one
(mysql Ver 12.22 Distrib 4.0.22, for portbld-freebsd4.10 (i386))
are doing this.
Tcl version is 8.4
vm.zone:
ITEM SIZE LIMIT USED FREE REQUESTS
PIPE: 160, 0, 13, 89, 2208898
SWAPMETA: 160, 233016, 0, 0, 0
unpcb: 160, 0, 13, 62, 18543
ripcb: 192, 12328, 0, 42, 5
syncache: 160, 15359, 0, 51, 1342401
tcpcb: 576, 12328, 539, 3059, 1341005
udpcb: 192, 12328, 3, 39, 9904
socket: 224, 12328, 556, 3064, 1369458
DIRHASH: 1024, 0, 652, 4, 767
KNOTE: 64, 0, 1, 127, 7589
VNODE: 192, 0, 33713, 101, 33713
NAMEI: 1024, 0, 0, 16, 11767321
VMSPACE: 192, 0, 39, 89, 585870
PROC: 416, 0, 72, 75, 585929
DP fakepg: 64, 0, 0, 0, 0
PV ENTRY: 28, 2281256, 78652, 445576, 435851412
MAP ENTRY: 48, 0, 1084, 829, 40997106
KMAP ENTRY: 48, 57423, 265, 119, 2234109
MAP: 108, 0, 7, 3, 7
VM OBJECT: 92, 0, 26533, 211, 15431058
-- A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet and in e-mail? Murray Taylor Bytecraft Systems P: +61 3 8710 2555 F: +61 3 8710 2599 D: +61 3 9238 4275 E: mtaylor@bytecraft.com.au --------------------------------------------------------------- The information transmitted in this e-mail is for the exclusive use of the intended addressee and may contain confidential and/or privileged material. Any review, re-transmission, dissemination or other use of it, or the taking of any action in reliance upon this information by persons and/or entities other than the intended recipient is prohibited. If you received this in error, please inform the sender and/or addressee immediately and delete the material. E-mails may not be secure, may contain computer viruses and may be corrupted in transmission. Please carefully check this e-mail (and any attachment) accordingly. No warranties are given and no liability is accepted for any loss or damage caused by such matters. --------------------------------------------------------------- ***This Email has been scanned for Viruses by MailMarshal.*** _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
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