Every day during the generation of some reports the mysql process takes up 1 or 2 cores (100%). The problem is that the whole server becomes unresponsive during that time. I can't ssh, postfix doesn't work, apache neither. I can however ping the server. Cronjobs also work, so I'm currently saving top's output every other minute to a file.
There are more cores available, the memory usage is not that high so I don't know why this happens. There is not much I can do about the application that does the reports, but I find it very strange that everything else stops working when mysql is overloaded. Load average goes to around 1,5. After everything is over things start to behave normally. Is there anything I can do about it?
Ubuntu 12.04 with kernel 3.13 on a physical server.
top - 21:51:02 up 82 days, 13:57, 8 users, load average: 1.19, 1.21, 1.15 Tasks: 367 total, 1 running, 364 sleeping, 0 stopped, 2 zombie Cpu(s): 1.2%us, 0.9%sy, 1.4%ni, 95.7%id, 0.8%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 16274920k total, 13190728k used, 3084192k free, 284272k buffers Swap: 4095996k total, 1006148k used, 3089848k free, 4570996k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 20794 mysql 20 0 3904m 893m 5260 S 100 5.6 2810:00 mysqld 19807 otrs 20 0 211m 46m 5560 S 75 0.3 0:00.39 otrs.PostMaster 14 root 20 0 0 0 0 S 2 0.0 20:49.52 rcuos/6