https://bz.apache.org/bugzilla/show_bug.cgi?id=63612
> with a small project reproducing it?
Unfortunately not easily extractable/reproducible
Maybe :
th = new Thread() {
@Override
public void run() {
« do something that requires a connection from the pool »
}
} ;
th.set getContextClassLoader( null ) ;
th.run() ;
Von: Romain Manni-Bucau <[email protected]>
Gesendet: Donnerstag, 25. Juli 2019 08:06
An: Tomcat Developers List <[email protected]>
Betreff: Re: PooledConnection#connectUsingDriver,
Thread.currentThread().getContextClassLoader() is null
Le jeu. 25 juil. 2019 à 07:46, Clemens Wyss DEV
<[email protected]<mailto:[email protected]>> a écrit :
< mais c'était rapide 😉 >
>+1
should/can I file a bug?
Guess so, with a small project reproducing it?
> init at bootstrap the pool (initial size) to ensure it is in one tomcat
> classloader
how would you achieve this? By setting «initialSize» to «maxSize» in
PoolProperties?
1 should be sufficient, however tomcat-jdbc (vs dbcp2 for instance) loads it
per connection and not once for all the pool
(https://github.com/apache/tomcat/blob/master/modules/jdbc-pool/src/main/java/org/apache/tomcat/jdbc/pool/PooledConnection.java#L196)
which is likely 1. Bad for perf but moreover 2. Buggy if the classloader
changes between usages of a connection in apps. Loader, driver should be loaded
once and potentially the datasource be duplicated per app if needed (driver in
the app) IMHO. This would also fix your NPE transitively ;).
----------------------------------------------------------
Von: Romain Manni-Bucau <[email protected]<mailto:[email protected]>>
Gesendet: Donnerstag, 25. Juli 2019 07:30
An: Tomcat Developers List <[email protected]<mailto:[email protected]>>
Betreff: Re: PooledConnection#connectUsingDriver,
Thread.currentThread().getContextClassLoader() is null
+1, there is no real other option AFAIK until you init at bootstrap the pool
(initial size) to ensure it is in one tomcat classloader.
Le jeu. 25 juil. 2019 à 07:08, Clemens Wyss DEV
<mailto:[email protected]<mailto:[email protected]>> a écrit :
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:http://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:http://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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