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icon5.gif  Forum hangs with apparent locking problems (V2.5.2) [message #15926] Fri, 09 January 2004 16:57 Go to next message
wfjmueller is currently offline  wfjmueller   Germany
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This is a Problem, not a Bug report !
In a V2.5.2 installation (using mySQL) we have the following problem:
  1. we had some general networking problems, causing various effects, among them maybe some bad and/or aborted FUDforum transactions
  2. after a reboot the forum worked only intermittently, it hung after a few transactions, or returned blank pages.
  3. we run the consistency check, no problems
  4. the forum still doesn't work (see 2.). The error log shows entries like
    (index.php) 1100: Table 's' was not locked with LOCK TABLES 
    Query: SELECT s.id AS sid, s.ses_id,....
    FROM ff_ses s INNER JOIN ff_users u ON....

So apparently there are locking problems, even though the system was rebooted. Since the consistency checker doesn't complain, it's not clear what to do to recover.
Re: Forum hangs with apparent locking problems (V2.5.2) [message #15937 is a reply to message #15926] Sat, 10 January 2004 02:21 Go to previous messageGo to next message
Ilia is currently offline  Ilia   Canada
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upgrade to 2.6

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Re: Forum hangs with apparent locking problems (V2.5.2) [message #15944 is a reply to message #15937] Sat, 10 January 2004 09:31 Go to previous messageGo to next message
wfjmueller is currently offline  wfjmueller   Germany
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Ilia wrote on Sat, 10 January 2004 03:21

upgrade to 2.6

I'd very much appreciate if you could say in a few words about what when wrong here. We tried for quite some time to diagnose the problem and get the forum back afloat, but failed. Since a reboot didn't help we truly wondered what got corrupted, whether it is the mysql database (but checks look fine) or some of the files the forum creates. We are just in a test phase right now, but in an operational forum a breakdown like we had would be a real and very visible problem. Upgrade is an option now, but what would you have said 3 month ago ?
Re: Forum hangs with apparent locking problems (V2.5.2) [message #15953 is a reply to message #15944] Sat, 10 January 2004 17:38 Go to previous messageGo to next message
Ilia is currently offline  Ilia   Canada
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If you had this problem prior to 2.6.0 release I'd probably try to debug it Wink. But at this point it is silly to do unless you can confirm the problem with 2.6.0 since the source code had changed dramatically.


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Re: Forum hangs with apparent locking problems (V2.5.2) [message #15968 is a reply to message #15953] Sat, 10 January 2004 21:11 Go to previous messageGo to next message
wfjmueller is currently offline  wfjmueller   Germany
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I see your argument, but try to see our side. The forum went down, and stayed there. Obvious corruption, caused probably by a networking problem. So that sort of thing is not reproducible, but something similar will occur again sooner or later for sure. So we'd like to understand the mechanism which cause such failures as much as we like to get it fixed. So given the history and symptoms, we'd highly appreciate some hints. Where would you look first, into the database state or contents, or into FUD generated files ?

Here the full text of a typical error log entry:
(index.php) 1100: Table 's' was not locked with LOCK TABLES
Query: SELECT s.id AS sid, s.ses_id, s.data, s.returnto, t.id AS
theme_id, t.lang, t.name AS theme_name, t.locale, t.theme,
t.pspell_lang, u.alias, u.append_sig, u.show_sigs,
u.show_avatars, u.show_im, u.posts_ppg, u.time_zone, u.sig,
u.last_visit, u.email_conf, u.last_read, u.default_view,
u.is_mod, u.cat_collapse_status, u.ignore_list, u.acc_status,
u.ignore_list, u.buddy_list, u.id, u.group_leader_list, u.coppa,
u.blocked, u.email, u.login, u.notify, u.pm_notify, u.last_read,
u.pm_messages FROM ff_ses s INNER JOIN ff_users u ON u.id=(CASE
WHEN s.user_id>2000000000 THEN 1 ELSE s.user_id END) INNER JOIN
ff_themes t ON t.id=u.theme WHERE
s.ses_id='b890d962aab651a5c0b3a64a98b14449'
Server Version: 3.23.49-log 
Re: Forum hangs with apparent locking problems (V2.5.2) [message #15971 is a reply to message #15968] Sat, 10 January 2004 22:08 Go to previous messageGo to next message
Ilia is currently offline  Ilia   Canada
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The first thing I'd do is disable persistent connections (if you got them enabled). Then switching to unix domain socket interface instead of TCP/IP if the mysql server is the webserver as well.

FUDforum Core Developer
Re: Forum hangs with apparent locking problems (V2.5.2) [message #16041 is a reply to message #15971] Mon, 12 January 2004 19:58 Go to previous messageGo to next message
wfjmueller is currently offline  wfjmueller   Germany
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We disabled persistent connections and used unix domain sockets, as you suggested, and now the forum runs again, no hangups anymore. Does this indicate anything obvious for you, something we should look for before we upgrade to 2.6.0 later this week ?
Re: Forum hangs with apparent locking problems (V2.5.2) [message #16044 is a reply to message #16041] Mon, 12 January 2004 20:27 Go to previous messageGo to next message
Ilia is currently offline  Ilia   Canada
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It means that problem was likely due to persistent connections, these often cause problems and the general recommendation is not to use them.

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Re: Forum hangs with apparent locking problems (V2.5.2) [message #16097 is a reply to message #16044] Wed, 14 January 2004 10:03 Go to previous messageGo to next message
wfjmueller is currently offline  wfjmueller   Germany
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Ilia wrote on Mon, 12 January 2004 21:27

It means that problem was likely due to persistent connections, these often cause problems and the general recommendation is not to use them.

The Admin Panel in 2.5.2 states
Use Persistent Connections:
Whether or not to use persistent connections. Highly recommended unless you have a good reason not to

No doubt, your suggestion to disable them helped to get the forum afloat again. But there is apparently a discrepancy between your statement "the general recommendation is not to use them" and the text in the admin panel "Highly recommended unless...".
Re: Forum hangs with apparent locking problems (V2.5.2) [message #16103 is a reply to message #16097] Wed, 14 January 2004 16:27 Go to previous message
Ilia is currently offline  Ilia   Canada
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The comment is changed in 2.6.0

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