Date: Thu, 29 Sep 2005 09:28:28 +1000 From: "Murray Taylor" <MTaylor@bytecraft.com.au> To: <freebsd-hackers@freebsd.org> Subject: System hang / extreme slowdown under MySQL Message-ID: <04E232FDCD9FBE43857F7066CAD3C0F1053AD6@svmailmel.bytecraft.internal>
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We are using MySQL on a FreeBSD box for one of our systems and recently after doing a number of application code changes to=20 support a new client the system experiecned what seemed to be=20 a total hang. It didnt crash per se, no log messages=20 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=20 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=20 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=20 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=20 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:=20 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=20 causing the hangs? The system is=20 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 =20 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 --=20 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.=20 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.***
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