List:General Discussion« Previous MessageNext Message »
From:Michael Widenius Date:August 27 1999 8:13pm
Subject:Re: Large scale performance of Mysql?
View as plain text  
>>>>> "Yan" == Yan Zhang Chen <yzc@stripped> writes:

Yan> On Mon, 23 Aug 1999, Michael Widenius wrote:
>> Hi!
>> >>>>> "Terry" == Terry Brown <Terry.Brown@stripped>
> writes:
Terry> Hi all,
Terry> I have a query for anyone running Mysql with large concurrency via 
Terry> CGI.  This is a follow up to a post I sent about 3 months ago.
Terry> The full specifications are listed below and you'll probably see, I've 
Terry> tried a lot of configurations.
Terry> We need mysql to accept ~200 concurrent connections (via Perl CGIs) and 
Terry> each of those connections runs through 4 perl CGI's and makes approximately 
Terry> 50selects, 20inserts over the 4 scripts (70x200=14000 interactions).  I can 
Terry> test everything with Apache benchmark with 400 concurrent connections to 
Terry> the first script (the login script) once.  This will 95% of the time 
Terry> succeed without any errors and send the system load to ~80-120.  If it is 
Terry> tried again (even after the system load drops back down) there are a number 
Terry> of failures reported by Apache benchmark and looking in the logs reveals a 
Terry> Can't connect to Mysql server.
>> It's very likely that  you get this error because of the delay when a
>> TCP/IP connection is closed (typically 30 seconds).
>> The fix is to use persistent connections and/or increase the number of 
>> active TCP/IP connections your OS (not mysqld) can handle
>> This should be as many connections that you get during 30 seconds).

Yan> We had same experience a while ago; we can't use persistent connection
Yan> from PHP, because mysqld would get lots of zombie threads hanging (which
Yan> results in high load (90+%) on the mysqld host). We are running on
Yan> Digital's Unix. We didn't have the time/resource to try resolving this issue
Yan> (I don't really know whether it's caused by the server or client end).


If a mysqld thread because a zombie, then there is a bug in mysqld or
in the thread library.

I am sorry that you didn't have time to track down the problem (It's
usually don't that hard if one follows the recommendations from the
MySQL manual)

Large scale performance of Mysql?Terry Brown19 Aug
  • Large scale performance of Mysql?sinisa19 Aug
  • Re: Large scale performance of Mysql?Scott Hess19 Aug
  • Large scale performance of Mysql?Michael Widenius23 Aug
    • Re: Large scale performance of Mysql?Yan Zhang Chen23 Aug
      • Re: Large scale performance of Mysql?Michael Widenius27 Aug