Just started getting these today- stopped apache, stopped and restarted mysqld, started apache... things go ok for a bit, errors come for a bit, things go ok for a bit...
Error from error_logs in Apache...
[Mon Oct 1 14:56:43 2007] [warn] [client 24.254.82.147] [/webwork2/Math34A-01-F07-Wei/hw2/6/] DBI connect('webwork','webworkWrite',...) failed: Too many connections at /opt/pg/lib/WeBWorK/PG/ImageGenerator.pm line 427\n
[Mon Oct 1 14:56:43 2007] [error] [client 24.254.82.147] [/webwork2/Math34A-01-F07-Wei/hw2/6/] Can't call method "prepare" on an undefined value at /opt/pg/lib/WeBWorK/PG/ImageGenerator.pm line 429.\n\n * in WeBWorK::PG::Local::new called at line 52 of /opt/webwork2//lib/WeBWorK/PG.pm\n * in WeBWorK::PG::new called at line 616 of /opt/webwork2//lib/WeBWorK/ContentGenerator/Problem.pm\n * in WeBWorK::ContentGenerator::Problem::pre_header_initialize called at line 169 of /opt/webwork2//lib/WeBWorK/ContentGenerator.pm\n * in WeBWorK::ContentGenerator::go called at line 338 of /opt/webwork2//lib/WeBWorK.pm
[Mon Oct 1 14:56:48 2007] [warn] [client 24.254.82.147] [/webwork2/Math34A-01-F07-Wei/hw2/4/] DBI connect('webwork','webworkWrite',...) failed: Too many connections at /opt/pg/lib/WeBWorK/PG/ImageGenerator.pm line 427\n
[Mon Oct 1 14:56:48 2007] [error] [client 24.254.82.147] [/webwork2/Math34A-01-F07-Wei/hw2/4/] Can't call method "prepare" on an undefined value at /opt/pg/lib/WeBWorK/PG/ImageGenerator.pm line 429.\n\n * in WeBWorK::PG::Local::new called at line 52 of /opt/webwork2//lib/WeBWorK/PG.pm\n * in WeBWorK::PG::new called at line 616 of /opt/webwork2//lib/WeBWorK/ContentGenerator/Problem.pm\n * in WeBWorK::ContentGenerator::Problem::pre_header_initialize called at line 169 of /opt/webwork2//lib/WeBWorK/ContentGenerator.pm\n * in WeBWorK::ContentGenerator::go called at line 338 of /opt/webwork2//lib/WeBWorK.pm
[Mon Oct 1 14:56:54 2007] [warn] [client 24.254.82.147] [/webwork2/Math34A-01-F07-Wei/hw2/] DBI connect('webwork','webworkWrite',...) failed: Too many connections at /opt/pg/lib/WeBWorK/PG/ImageGenerator.pm line 427
[Mon Oct 1 14:56:54 2007] [error] [client 24.254.82.147] [/webwork2/Math34A-01-F07-Wei/hw2/] Can't call method "prepare" on an undefined value at /opt/pg/lib/WeBWorK/PG/ImageGenerator.pm line 429.\n * in WeBWorK::PG::Local::new called at line 52 of /opt/webwork2//lib/WeBWorK/PG.pm\n * in WeBWorK::PG::new called at line 242 of /opt/webwork2//lib/WeBWorK/ContentGenerator/ProblemSet.pm\n * in WeBWorK::ContentGenerator::ProblemSet::info called at line 152 of /opt/webwork2//lib/WeBWorK/Template.pm\n * in WeBWorK::Template::template called at line 480 of /opt/webwork2//lib/WeBWorK/ContentGenerator.pm\n * in WeBWorK::ContentGenerator::content called at line 188 of /opt/webwork2//lib/WeBWorK/ContentGenerator.pm\n * in WeBWorK::ContentGenerator::go called at line 338 of /opt/webwork2//lib/WeBWorK.pm
I'm looking in to mysql settings at the moment, but anyone ever see this? We're running WW 2.3.1 on a DELL 2850 (dual 1.8GHz) with 3 GB RAM, and basically no other services, for 1500 students. The quarter just started, and I'm starting to get email, so any quick thoughts would be very much appreciated.
Thanks-
Fuzzy
So, edited /etc/my.cnf and raised max_connections under [myslqd] to 300 - so far so good.
However when I issue a show processlist; in mysql I noticed that the majority of processes are in Sleep Command. Perhaps I should also shorten the timeout period?
Googling info on that right now.
Fuzzy
However when I issue a show processlist; in mysql I noticed that the majority of processes are in Sleep Command. Perhaps I should also shorten the timeout period?
Googling info on that right now.
Fuzzy
So now the question is how much RAM will the maximum mysql connections take up? I'm referencing this site...
http://forums.mysql.com/read.php?24,15350,32027#msg-32027
and it gives some ominous results. I imagine mysql performance tuning is, well, a time consuming job unto itself. Regardless, following that calc, and assuming that the
show global variables;
command yields values in bytes, for a max_connections of 300 I get a RAM usage of...
3.1 GB (if I'm calculating it correctly). Yikes. That would explain my system crash yesterday when I only had a total of 3GB in the system. I presume there are certain factors that can be adjusted to performance tune mysql better for webwork- but that sort of db administration will take some careful studying before changing values I have no idea what they do.
Checking last night, my processor load never exceeded 2, which is great (for 2500 students), and I think my connections in mysqld show processlist; never exceeded 200. I might lower my max_connections if the server starts paging out to swap and the load increases.
another good reference page...
http://www.mysqltalk.org/per-thread-memory-use-question-vt158608.html
Take care,
Fuzzy
http://forums.mysql.com/read.php?24,15350,32027#msg-32027
and it gives some ominous results. I imagine mysql performance tuning is, well, a time consuming job unto itself. Regardless, following that calc, and assuming that the
show global variables;
command yields values in bytes, for a max_connections of 300 I get a RAM usage of...
3.1 GB (if I'm calculating it correctly). Yikes. That would explain my system crash yesterday when I only had a total of 3GB in the system. I presume there are certain factors that can be adjusted to performance tune mysql better for webwork- but that sort of db administration will take some careful studying before changing values I have no idea what they do.
Checking last night, my processor load never exceeded 2, which is great (for 2500 students), and I think my connections in mysqld show processlist; never exceeded 200. I might lower my max_connections if the server starts paging out to swap and the load increases.
another good reference page...
http://www.mysqltalk.org/per-thread-memory-use-question-vt158608.html
Take care,
Fuzzy
And from the WW archives...
http://webhost.math.rochester.edu/webworkdocs/discuss/msgReader$2273
http://webhost.math.rochester.edu/webworkdocs/discuss/msgReader$2273