解决tomcat占用CPU过高
因生产环境tomcat占用CPU持续过高，负载过高，重启tomcat过于缓慢，参与网上资料，解决tomcat占用CPU过高，重启缓慢问题1、通过top命令找出占用CPU高的PID
top - 15:52:18 up 93 days,2:23,1 user,load average: 9.05, 9.00, 9.17
Tasks:98 total, 1 running,97 sleeping, 0 stopped, 0 zombie
Cpu(s): 41.0%us, 59.0%sy,0.0%ni,0.0%id,0.0%wa,0.0%hi,0.0%si,0.0%st
Mem: 3926224k total,1070236k used,2855988k free, 51508k buffers
Swap:6143992k total, 286684k used,5857308k free, 95404k cached
PID USER PRNIVIRTRESSHR S %CPU %MEM TIME+COMMAND
4834 root 20 0 1953m62m 1848 S 99.21.628369:16 java
20399 root 20 0 1980m 650m 5724 S0.3 17.0 6:31.53 java
1 root 20 0 19348904632 S0.00.0 0:12.21 init
2 root 20 0 0 0 0 S0.00.0 0:00.00 kthreadd
3 root RT 0 0 0 0 S0.00.0 0:00.00 migration/0
4 root 20 0 0 0 0 S0.00.0 2:50.30 ksoftirqd/0
5 root RT 0 0 0 0 S0.00.0 0:00.00 migration/0
6 root RT 0 0 0 0 S0.00.0 0:11.41 watchdog/0
7 root 20 0 0 0 0 S0.00.047:36.80 events/0
8 root 20 0 0 0 0 S0.00.0 0:00.00 cgroup
9 root 20 0 0 0 0 S0.00.0 0:00.00 khelper
10 root 20 0 0 0 0 S0.00.0 0:00.00 netns
11 root 20 0 0 0 0 S0.00.0 0:00.00 async/mgr
12 root 20 0 0 0 0 S0.00.0 0:00.00 pm
13 root 20 0 0 0 0 S0.00.0 0:22.66 sync_supers
14 root 20 0 0 0 0 S0.00.0 0:21.60 bdi-default
15 root 20 0 0 0 0 S0.00.0 0:00.00 kintegrityd/0
16 root 20 0 0 0 0 S0.00.0 1:41.28 kblockd/0
17 root 20 0 0 0 0 S0.00.0 0:00.00 kacpid
18 root 20 0 0 0 0 S0.00.0 0:00.00 kacpi_notify
19 root 20 0 0 0 0 S0.00.0 0:00.00 kacpi_hotplug
2、通过ps aux | grep pid 可以进一步确定是tomcat进程出了问题
3、显示线程列表
# ps -mp 4834 -o THREAD,tid,time
USER %CPU PRI SCNT WCHANUSER SYSTEM TID TIME
root 85.4 - - - - - - 19-16:49:52
root 0.019 - futex_ - -4834 00:00:00
root 0.019 - futex_ - -4835 00:00:00
root 0.019 - futex_ - -4836 00:00:47
root 0.019 - futex_ - -4837 00:00:00
root 0.019 - futex_ - -4838 00:00:01
root 0.019 - futex_ - -4839 00:00:00
root 0.019 - futex_ - -4840 00:00:20
root 0.019 - futex_ - -4841 00:00:21
root 0.019 - futex_ - -4842 00:00:00
root 0.019 - futex_ - -4843 00:12:07
root 0.019 - futex_ - -4844 00:00:00
root 9.419 - - - -4863 2-04:30:24
root 9.419 - - - -4871 2-04:30:20
root 9.419 - - - -4875 2-04:30:20
root 9.419 - - - -4890 2-04:30:20
root 9.419 - - - -4893 2-04:30:20
root 9.419 - - - -4896 2-04:30:20
root 9.419 - - - -4898 2-04:30:20
root 9.419 - - - -4904 2-04:30:20
root 0.019 - futex_ - -4916 00:00:00
root 0.019 - futex_ - -4917 00:00:10
root 0.019 - futex_ - -4918 00:00:00
root 0.019 - futex_ - -4919 00:00:00
root 0.019 - futex_ - -4920 00:00:00
root 0.019 - futex_ - -4921 00:00:00
root 0.019 - futex_ - -4922 00:00:00
root 0.019 - futex_ - -4923 00:00:00
root 0.019 - futex_ - -4924 00:00:00
root 0.019 - futex_ - -4925 00:00:00
root 0.019 - futex_ - -4926 00:00:00
root 0.019 - futex_ - -4927 00:00:00
root 0.019 - futex_ - -4928 00:00:00
root 0.019 - futex_ - -4929 00:00:00
root 0.019 - futex_ - -4930 00:00:00
root 0.019 - futex_ - -4931 00:00:00
root 0.019 - futex_ - -4932 00:00:00
root 0.019 - futex_ - -4933 00:00:00
root 0.019 - futex_ - -4934 00:00:00
root 0.019 - futex_ - -4935 00:00:00
root 0.019 - futex_ - -4936 00:00:00
root 0.019 - futex_ - -4937 00:00:00
root 0.019 - futex_ - -4938 00:00:00
root 0.019 - futex_ - -4939 00:00:00
root 0.019 - futex_ - -4940 00:00:00
root 0.019 - futex_ - -4941 00:00:00
root 0.019 - futex_ - -4942 00:00:00
root 0.019 - futex_ - -4943 00:00:00
root 0.019 - futex_ - -4944 00:00:00
root 0.019 - futex_ - -4945 00:00:00
root 0.019 - futex_ - -4946 00:00:00
root 0.019 - futex_ - -4947 00:00:00
root 0.019 - futex_ - -4948 00:00:00
root 0.019 - futex_ - -4949 00:00:00
root 0.019 - futex_ - -4950 00:00:00
root 0.019 - futex_ - -4951 00:00:00
root 0.019 - futex_ - -4952 00:00:00
root 0.019 - futex_ - -4953 00:00:00
root 0.019 - futex_ - -4954 00:00:00
root 0.019 - futex_ - -4955 00:00:00
root 0.019 - futex_ - -4956 00:00:00
root 0.019 - futex_ - -4957 00:00:00
root 0.019 - futex_ - -4958 00:00:00
root 0.019 - futex_ - -4959 00:00:00
root 0.019 - futex_ - -4960 00:00:00
root 0.019 - futex_ - -4961 00:00:00
root 0.019 - futex_ - -4962 00:00:00
root 0.019 - futex_ - -4963 00:00:00
root 0.019 - futex_ - -4964 00:00:00
root 0.019 - futex_ - -4965 00:00:00
root 0.019 - futex_ - -4966 00:00:00
root 0.019 - futex_ - -4967 00:00:00
root 0.019 - futex_ - -4968 00:00:00
root 0.019 - futex_ - -4969 00:00:00
root 0.019 - futex_ - -4970 00:00:00
root 0.019 - futex_ - -4971 00:00:00
root 0.019 - futex_ - -4972 00:00:00
root 0.019 - futex_ - -4973 00:00:00
root 0.019 - futex_ - -4974 00:00:00
root 0.019 - futex_ - -4975 00:00:00
root 0.019 - futex_ - -4976 00:00:00
root 0.019 - futex_ - -4977 00:00:00
root 0.019 - futex_ - -4978 00:00:00
root 0.019 - futex_ - -4979 00:00:00
root 0.019 - futex_ - -4980 00:00:00
root 0.019 - futex_ - -4981 00:00:00
root 0.019 - futex_ - -4982 00:00:00
root 0.019 - futex_ - -4983 00:00:00
root 0.019 - futex_ - -4984 00:00:00
root 0.019 - futex_ - -4985 00:00:00
root 0.019 - futex_ - -4986 00:00:00
root 0.019 - futex_ - -4987 00:00:00
root 0.019 - futex_ - -4988 00:00:00
root 0.019 - futex_ - -4989 00:00:00
root 0.019 - futex_ - -4990 00:00:00
root 0.019 - futex_ - -4991 00:00:00
root 0.019 - futex_ - -4992 00:00:00
root 0.019 - futex_ - -4993 00:00:00
root 0.019 - futex_ - -4994 00:00:00
root 0.019 - futex_ - -4995 00:00:00
root 0.019 - futex_ - -4996 00:00:00
root 0.019 - futex_ - -4997 00:00:00
root 0.019 - futex_ - -4998 00:00:00
root 0.019 - futex_ - -4999 00:00:00
root 0.019 - futex_ - -5000 00:00:00
root 0.019 - futex_ - -5001 00:00:00
root 0.019 - futex_ - -5002 00:00:00
root 0.019 - futex_ - -5003 00:00:00
root 0.019 - futex_ - -5004 00:00:00
root 0.019 - futex_ - -5005 00:00:00
root 0.019 - futex_ - -5006 00:00:00
root 0.019 - futex_ - -5007 00:00:00
root 0.019 - futex_ - -5008 00:00:00
root 0.019 - futex_ - -5009 00:00:00
root 0.019 - futex_ - -5010 00:00:00
root 0.019 - futex_ - -5011 00:00:00
root 0.019 - futex_ - -5012 00:00:00
root 0.019 - futex_ - -5013 00:00:00
root 0.019 - futex_ - -5014 00:00:00
root 0.019 - futex_ - -5015 00:00:00
root 0.019 - futex_ - -5016 00:00:00
root 0.019 - futex_ - -5017 00:00:00
root 0.019 - futex_ - -5018 00:00:00
root 0.019 - futex_ - -5019 00:00:00
root 0.019 - futex_ - -5020 00:00:00
root 0.019 - futex_ - -5021 00:00:00
root 0.019 - futex_ - -5022 00:00:00
root 0.019 - futex_ - -5023 00:00:00
root 0.019 - futex_ - -5024 00:00:00
root 0.019 - futex_ - -5025 00:00:00
root 0.019 - futex_ - -5026 00:00:00
root 0.019 - futex_ - -5027 00:00:00
root 0.019 - futex_ - -5028 00:00:00
root 0.019 - futex_ - -5029 00:00:00
root 0.019 - futex_ - -5030 00:00:00
root 0.019 - futex_ - -5031 00:00:00
root 0.019 - futex_ - -5032 00:00:00
root 0.019 - futex_ - -5033 00:00:00
root 0.019 - futex_ - -5034 00:00:00
root 0.019 - futex_ - -5035 00:00:00
root 0.019 - futex_ - -5036 00:00:00
root 0.019 - futex_ - -5037 00:00:00
root 0.019 - futex_ - -5038 00:00:00
root 0.019 - futex_ - -5039 00:00:00
root 0.019 - futex_ - -5040 00:00:00
root 0.019 - futex_ - -5041 00:00:00
root 0.019 - futex_ - -5042 00:00:00
root 0.019 - futex_ - -5043 00:00:00
root 0.019 - futex_ - -5044 00:00:00
root 0.019 - futex_ - -5047 00:00:00
root 0.019 - futex_ - -5053 00:00:00
root 0.019 - futex_ - -5264 00:00:00
root 9.519 - - - -7041 2-04:30:17
root 0.019 - futex_ - -7366 00:00:00
root 0.019 - futex_ - -7383 00:00:00
root 0.019 - futex_ - -7385 00:00:00
root 0.019 - futex_ - -7387 00:00:00
root 0.019 - futex_ - -7388 00:00:00
root 0.019 - futex_ - -7390 00:00:00
root 0.019 - futex_ - -7397 00:00:35
root 0.019 - skb_re - - 24683 00:00:00 通过观察共计7041、4904、4898、4896、4893、4890、4875、4871、4863九个tid占用了CPU
4、打印线程的堆栈信息
jstack pid | grep tid -A 30 此处不一一列表各tid的堆栈信息了，在其中一个的tid堆栈信息中找到了问题的原因
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