Hi all, I am a new subscriber of this list.
I have a question that have confuse me for a long time.
I am currently running MySQL-3.23.32 on Debian(woody)
with kernel 2.4.x on a i386 box /w 1G Ram..
We are currently runing two different kind of database on the
same server. One of them is a few table in a Database, each of
them have over 10,000 rows, a Merge table in it.
Another one is over 30,000 tables in a single Database, with no
more then row in each of them.. ( Don't ask me why that
happended.. I am not the one design this.) All of them are
MyISAM tables.
The server is now facing about 200 queries/second on average,
and a peak of about 430 queries. All of them are simple LOCK,
UNLOCK, SELECT, INSERT.. no join table, no union, no sort..
only simple queries.. most of them have no more then 10 rows
of answer.
Recently, we done a system upgrade, from kernel 2.4.2 to kernel
2.4.4 for a RealTex LAN Card SMP fix. At about the same time,
we have changed some of our program... introducing some rename
table and drop tables too.. a few days later,
the sql server start core dumping on usual loading.. We have try
using --debug option, but it can't help as it's handling too few
queries per second, and the sql server just don't dump...
I am quite sure that's was not damaged table problem, as we have run
myisamchk many times, with differenet options.. -a -f -o -S -e -m -q
for over ten times..
After hesitating for an moment, we desided to upgrade to 3.23.35
(ar.. in fact, we have try 3.23.31, .32, .35, .37 and .38 ... the following
situation hanppens on .35, .37, and .38 )
After starting the mysql server seems work fine... but.... huh?
why that's so slow? it's running with a maximum of 65 queries/seconds..
the load average climb up quickly... "top" tell me that mysqld is forking
childs, each of them dieing quickly, keeping on average of 80 childs at
the same moment..(child? or thread? fix me if i am wrong..)
And nothing abnormal are printed to (hostname).err.. this make me more
confusing..
i have heard that recent kernel will give childs created with fork() a
higher priority.. it that related?
Does anyone have the same problem before? should i file this as a bug?
( ar.. i know i am not providing enough infomation.. but.. whenever I
start mysql with --debug, it don't dump, as i have said.... )
anyway.. i will try a downgrade to kernel 2.4.2 this night..
FYI, we compile mysql with "--without-bench --without-docs --with-debug".
we have tried different version of gcc, all of them are debian's cvs
relaease.
Here goes my my.cnf, the flush is something i added i discover this..
to protect my tables:
[client]
port = 3306
socket = /tmp/mysql.sock
[mysqld]
port = 3306
socket = /tmp/mysql.sock
datadir = /usr/local/mysql/var
skip-locking
#enable-locking
flush
#temp-pool
core-file
user = root
set-variable = flush_time=10
set-variable = back_log=256
set-variable = key_buffer=8M
set-variable = max_allowed_packet=4M
set-variable = table_cache=2048
set-variable = sort_buffer=4M
set-variable = record_buffer=4M
set-variable = thread_concurrency=4
set-variable = myisam_sort_buffer_size=16M
set-variable = max_connect_errors=65536
set-variable = max_connections=512
myisam-recover = BACKUP,FORCE
log = /usr/local/mysql/var/dump.log
log-update
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