在tomcat中每一个用户请求都是一个线程，所以可以通过开启并使用线程池的方式来提高tomcat的性能。
配置：
参数说明：
| Attribute | Description |
| threadPriority （优先级） | (int) The thread priority for threads in the executor, the default is 5 (the value of theThread.NORM_PRIORITY constant) |
| daemon（守护进程） | (boolean) Whether the threads should be daemon threads or not, the default is true |
| namePrefix（名称前缀） | (String) The name prefix for each thread created by the executor. The thread name for an individual thread will be namePrefix+threadNumber |
| maxThreads（最大线程数） | (int) The max number of active threads in this pool, default is 200 |
| minSpareThreads（最小活跃线程数） | (int) The minimum number of threads always kept alive, default is 25 |
| maxIdleTime（空闲线程等待时间） | (int) The number of milliseconds before an idle thread shutsdown, unless the number of active threads are less or equal to minSpareThreads. Default value is 60000(1 minute) |
| maxQueueSize（最大的等待队里数，超过则请求拒绝） | (int) The maximum number of runnable tasks that can queue up awaiting execution before we reject them. Default value is Integer.MAX_VALUE |
| prestartminSpareThreads（是否在启动时就生成minSpareThreads个线程） | (boolean) Whether minSpareThreads should be started when starting the Executor or not, the default is false |
| threadRenewalDelay（重建线程的时间间隔） | (long) If aThreadLocalLeakPreventionListener is configured, it will notify this executor about stopped contexts. After a context is stopped, threads in the pool are renewed. To avoid renewing all threads at the same time, this option sets a delay between renewal of any 2 threads. The value is in ms, default value is 1000 ms. If value is negative, threads are not renewed.。重建线程池内的线程时，为了避免线程同时重建，每隔threadRenewalDelay（单位： ms ）重建一个线程。默认值为1000 ，设置为负则不重建 |
修改后如下：
