In my experiences, there're three reasons below. 1. Your network is not stable. 2. Your mysqld's parameter called max_allowed_packet is adjusted too small, trying to increase it. 3. Your mysqld's parameter called connect_timeout is adjusted too small, trying to increase it. On Thu, Oct 30, 2008 at 1:05 PM, mos <[EMAIL PROTECTED]> wrote:
> At 10:21 PM 10/29/2008, you wrote: > >> I've never had a lot of luck tracking down this sort of problem. One >> thing I've found to be a good first step is to add each server >> involved to the other server's /etc/hosts file (and restart MySQL so >> it notices). >> >> Don't have much more to offer other than the usual suspects: recent >> versions, persistent vs. non-persistent connections, etc. A long shot >> would be to make sure your always talking to the same database server- >> if you're doing, say, DNS round-robin or load balancing or something, >> maybe you're getting shunted to a different db server and it's killing >> the connection... don't know what your setup is. Another long shot in >> a multi-db-server config would be to make sure they all have different >> server ID's. >> >> Good luck... hopefully someone else has better advice :) >> >> Jake >> > > Just a guess, but maybe it's your network card? > > I'm using MySQL 5.01 with MyISAM tables and my application will > occasionally hang for hours in the midst of executing a simple 1 table > Select statement. I usually end up killing the program. There are no > processes running on the MySQL server. I think the problem was the number of > connections the program created. Although there were only at most 10 > simultaneous connections, my program when the query finished executing, it > threw the connection away and recreated a new one for each query, and MySQL > reported there were some 10k connections made to the server. I ended up > using connection pooling and now the number of connections reaches a high of > around 10 and I haven't had the problem since. > > Mike > > On Wed, Oct 29, 2008 at 2:47 AM, Waynn Lue <[EMAIL PROTECTED]> wrote: >> > We've started seeing mysql errors in the logs, and when i look at the >> output >> > of mysql_error() (in php), i get "lost connection to mysql server during >> > query". Here's an example stack trace: >> > >> > 'Can't connect to <name> database [Lost connection to MySQL server >> during >> > query]' >> > >> > Similarly, we're seeing stack traces here as well: >> > >> > 'Can't connect to <name> database []' >> > >> > I usually only see this mesasge when I don't use a connection for awhile >> and >> > it timeouts, but in this case, the connection is only opened for the >> > duration of a script, which can't be running for more than a second. The >> > mysql error logs don't show anything, and wait_timeout is set to 28800. >> > >> > At first, I thought it was because I was calling mysql_select_db too >> much, >> > so I ended up using two mysql connections per page load, but that didn't >> > seem to change anything. How can we prevent this error from happening, >> what >> > else can I do to diagnose this further? Google brings up some more >> > discussions about it, but nothing seems related to this, like >> packetsize. >> > This is happening when we select two ids from a database. And SHOW >> > PROCESSLIST shows that the number of connections aren't even coming >> close to >> > max connections. >> > >> > Thanks for any advice, >> > Waynn >> > >> >> -- >> MySQL General Mailing List >> For list archives: http://lists.mysql.com/mysql >> To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] >> > > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: > http://lists.mysql.com/[EMAIL PROTECTED] > > -- I'm a MySQL DBA in china. More about me just visit here: http://yueliangdao0608.cublog.cn
