[TYPO3-english] Saving pages in BE locks complete database

[Christopher Lörken]

Am 12.01.2010 16:30, schrieb Peter Russ:

> Please enable also slow queries log in Mysql as there might be other
> queries stopping the system.
>
> Peter.
>

Ok, I've enabled the slow query log and it just happened again. I've 
extracted the time frame in question and attached the
"mysqldumpslow -l" (-l == "don't subtract lock time from total time")
of that part of the log.

In this case, the longest taking query is definitely this one:
Count: 1  Time=876.00s (876s)  Lock=0.00s (0s)  Rows=0.0 (0), 
site[site]@localhost
   UPDATE pages
   SET
   SYS_LASTCHANGED='S'
   WHERE
   uid=N

Which, given that I did the magical alter pages to InnoDB, should never 
ever take that long should it? An update of a single primary key 
referenced row in an InnoDB table. And the accessed page is a seldomly 
accessed one so I don't even think that it got accessed during the 
timeframe in question.


Some notes on what we did exactly before this problem occured:

1)
I manually cleared the large cache tables in case we would get the slow 
DELETE * FROM ... queries from the page update
-> truncate table cache_hash;
-> truncate table cache_pages;

2) We logged in to the backend and changed a standard tt_content text 
element (which has a translation into a second language) and pressed 
"Save".
--> The browser never returned from "saving" since the database locked.

3) After about 5 Minutes, I stopped apache and a couple of minutes 
later, the db was cleared up and running again.


What I furthermore find interesting is, that saving just after something 
like that happened does too take some time, but tends to not lock the 
database. The same update with sys_lastchanged query took (when saving 
the same page 20 minutes later) 15 seconds.
Still too long but at least not locking.


Does anyone get any insight from this information?

Thanks a lot,

Christopher

-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: dumped_slow.log
URL: <http://lists.typo3.org/pipermail/typo3-english/attachments/20100127/0b3ce7a5/attachment.asc>