I tried posting this in the tomcat-users-ml, but I guess it rather fits here:
Context:
Debian GNU/Linux 9 \n \l
java version 1.8.0_162
Tomcat 8.5.35
>From time to time we are facing the follwing exception (call stack):
...
Caused by: java.sql.SQLException: Unable to load class: org.mariadb.jdbc.Driver
from ClassLoader:java.net.URLClassLoader@4c873330;ClassLoader:null
at
org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:292)
at
org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:212)
at
org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:736)
at
org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:668)
at
org.apache.tomcat.jdbc.pool.ConnectionPool.getConnection(ConnectionPool.java:198)
at
org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:132)
at org.apache.torque.Torque.getConnection(Torque.java:924)
... 53 common frames omitted
Caused by: java.lang.ClassNotFoundException: Unable to load class:
org.mariadb.jdbc.Driver from
ClassLoader:java.net.URLClassLoader@4c873330;ClassLoader:null
at
org.apache.tomcat.jdbc.pool.ClassLoaderUtil.loadClass(ClassLoaderUtil.java:56)
at
org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:280)
... 59 common frames omitted
Caused by: java.lang.ClassNotFoundException: Classloader is null
at
org.apache.tomcat.jdbc.pool.ClassLoaderUtil.loadClass(ClassLoaderUtil.java:40)
... 60 common frames omitted
According to the code (in PooledConnection# connectUsingDriver)
Thread.currentThread().getContextClassLoader() returns null
Googling for " Thread.currentThread().getContextClassLoader() is null" the
common demoniator seems to be `getContextClassLoader can be null`. If this is
true there should be
a) a null-check in PooledConnection# connectUsingDriver
b) if null, then there should be a fallback-Classloader (the system class
laoder?)
WDYT ?
Or any ideas why the given exception pops up from time to time
Thx
Clemens
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