2018-5-14 10:58:50 org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
: The web application [/SCM] registered the JBDC driver [com.alibaba.druid.mock.MockDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
2018-5-14 10:58:50 org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
: The web application [/SCM] registered the JBDC driver [com.microsoft.sqlserver.jdbc.SQLServerDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
2018-5-14 10:58:50 org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
: The web application [/SCM] registered the JBDC driver [com.alibaba.druid.proxy.DruidDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
2018-5-14 10:58:50 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
: The web application [/SCM] appears to have started a thread named [DefaultQuartzScheduler_QuartzSchedulerThread] but has failed to stop it. This is very likely to create a memory leak.
2018-5-14 10:58:50 org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap
: The web application [/SCM] created a ThreadLocal with key of type [net.sf.json.AbstractJSON$1] (value [net.sf.json.AbstractJSON$1@1b490621]) and a value of type [java.util.HashSet] (value [[]]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.
2018-5-14 10:59:05 org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor processChildren
: Exception invoking periodic operation: 
java.lang.OutOfMemoryError: PermGen space
2018-5-14 10:59:17 org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor processChildren
: Exception invoking periodic operation: 
java.lang.OutOfMemoryError: PermGen space

from yesterday to today, all the solutions to memory leaks on the Internet are not working.