Tomcat encounters a problem

1. Java.lang.OutOfMemoryError:PermGen Space

When you start the Tomcat service, report this error and check that the memory leaks

PermGen space is the full name of permanent Generation space, refers to the memory of the permanent storage area, this block of memory is mainly stored by the JVM class and meta information, class is loader will be placed in PermGen Space,
Unlike the heap area where the class instance (Instance) is stored, the GC (garbage Collection) does not clean up permgen space during the main program run time, so if you have many classes in your application, you are likely to appear PermGen Space Error,
This error is common when the Web server pre-compile the JSP. If you have a large number of third-party jars under your web app that are larger than the JVM's default size (4M), this error message will be generated.

Workaround: Manually set the MaxPermSize size

Find tomcat_home/bin/catalina.sh
In # OS specific support. $var _must_ is set to either True or FALSE. Add the following line above:
Java_opts= "-server-xx:permsize=64m-xx:maxpermsize=128m"

Tomcat encounters a problem