#10 ThreadLocal with key of type [null]

[king]

Running OpenGTS v2.2.7 with Tomcat v6.0.29 as windows service, I always got the following WARNing messages inside log file "catalina.2010-12-19.log",
I wonder what might cause thses problems.

Inside ThreadLocalMap.java, I tried to fix this problem by making a little change, but useless, this problem still comes up.

public V remove(Object key)
{
if (key == null)
return null;

return this.getMap().remove(key);
}

============================== [ catalina.2010-12-19.log ] =========================================

WARN: The web application [/track] appears to have started a thread named [Timer-1] but has failed to stop it. This is very likely to create a memory leak.
2010-12-19 23:19:22 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
WARN: The web application [/track] appears to have started a thread named [Timer-2] but has failed to stop it. This is very likely to create a memory leak.
2010-12-19 23:19:22 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
WARN: The web application [/track] appears to have started a thread named [Timer-3] but has failed to stop it. This is very likely to create a memory leak.
2010-12-19 23:19:22 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
WARN: The web application [/track] appears to have started a thread named [Timer-4] but has failed to stop it. This is very likely to create a memory leak.
2010-12-19 23:19:22 org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap
WARN: The web application [/track] created a ThreadLocal with key of type [null] (value [org.opengts.util.ThreadLocalMap$1@e76438]) and a value of type [java.util.Hashtable] (value [{jdbc:mysql://localhost:3306/gts?characterEncoding=UTF-8&useUnicode=true&characterSetResults=utf8=org.opengts.dbtools.DBConnection@177ab84}]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.
2010-12-19 23:19:22 org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap
WARN: The web application [/track] created a ThreadLocal with key of type [null] (value [org.opengts.util.ThreadLocalMap$1@e76438]) and a value of type [java.util.Hashtable] (value [{jdbc:mysql://localhost:3306/gts?characterEncoding=UTF-8&useUnicode=true&characterSetResults=utf8=org.opengts.dbtools.DBConnection@186b11c}]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.
2010-12-19 23:19:22 org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap
WARN: The web application [/track] created a ThreadLocal with key of type [null] (value [org.opengts.util.ThreadLocalMap$1@e76438]) and a value of type [java.util.Hashtable] (value [{jdbc:mysql://localhost:3306/gts?characterEncoding=UTF-8&useUnicode=true&characterSetResults=utf8=org.opengts.dbtools.DBConnection@44b7f7}]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.
2010-12-19 23:19:22 org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap
WARN:: The web application [/track] created a ThreadLocal with key of type [null] (value [org.opengts.util.ThreadLocalMap$1@e76438]) and a value of type [java.util.Hashtable] (value [{jdbc:mysql://localhost:3306/gts?characterEncoding=UTF-8&useUnicode=true&characterSetResults=utf8=org.opengts.dbtools.DBConnection@687ae0}]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.
2010-12-19 23:19:22 org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap
WARN: The web application [/track] created a ThreadLocal with key of type [null] (value [org.opengts.util.ThreadLocalMap$1@e76438]) and a value of type [java.util.Hashtable] (value [{jdbc:mysql://localhost:3306/gts?characterEncoding=UTF-8&useUnicode=true&characterSetResults=utf8=org.opengts.dbtools.DBConnection@ebaf12}]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.

[Saurabh Shastri]

I am facing the same problem. Does anybody has any clue?