> recent tomcat version
9.0.22 has the same class loading code as 8.5.35
https://jar-download.com/artifacts/org.apache.tomcat/tomcat-jdbc/9.0.22/source-code/org/apache/tomcat/jdbc/pool/PooledConnection.java
driver = (java.sql.Driver)
ClassLoaderUtil.loadClass(
poolProperties.getDriverClassName(),
PooledConnection.class.getClassLoader(),
Thread.currentThread().getContextClassLoader()
).getConstructor().newInstance();
Von: Romain Manni-Bucau <rmannibu...@gmail.com>
Gesendet: Montag, 29. Juli 2019 09:35
An: Tomcat Developers List <dev@tomcat.apache.org>
Betreff: Re: PooledConnection#connectUsingDriver,
Thread.currentThread().getContextClassLoader() is null
Can you give a try on a more recent tomcat version? Seems it works with master
version since the tomcat-jdbc module classloader is tried first before the tccl?
Tested with:
public class PooledConnectionTest {
@Test
public void avoidNPEWhenTcclIsNull() throws SQLException {
final PoolProperties poolProperties = new PoolProperties();
poolProperties.setDriverClassName("org.h2.Driver");
poolProperties.setUsername("sa");
poolProperties.setPassword("");
poolProperties.setUrl("jdbc:h2:mem:PooledConnectionTest_avoidNPEWhenTcclIsNull");
poolProperties.setMaxIdle(1);
poolProperties.setMinIdle(1);
poolProperties.setInitialSize(1);
poolProperties.setMaxActive(1);
ensureDataSourceIsValid(poolProperties);
final Thread thread = Thread.currentThread();
final ClassLoader testLoader = thread.getContextClassLoader();
thread.setContextClassLoader(null);
try {
ensureDataSourceIsValid(poolProperties);
} finally {
thread.setContextClassLoader(testLoader);
}
}
private void ensureDataSourceIsValid(final PoolProperties poolProperties)
throws SQLException {
final DataSource dataSource = new DataSource(poolProperties);
try (final Connection connection = dataSource.getConnection()) {
assertTrue(connection.isValid(5));
} finally {
dataSource.close();
}
}
}
Romain Manni-Bucau
@rmannibucau<https://twitter.com/rmannibucau> |
Blog<https://rmannibucau.metawerx.net/> | Old
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Le lun. 29 juil. 2019 à 07:36, Clemens Wyss DEV
<clemens...@mysign.ch<mailto:clemens...@mysign.ch>> a écrit :
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 <rmannibu...@gmail.com<mailto:rmannibu...@gmail.com>>
Gesendet: Donnerstag, 25. Juli 2019 08:06
An: Tomcat Developers List <dev@tomcat.apache.org<mailto:dev@tomcat.apache.org>>
Betreff: Re: PooledConnection#connectUsingDriver,
Thread.currentThread().getContextClassLoader() is null
Le jeu. 25 juil. 2019 à 07:46, Clemens Wyss DEV
<clemens...@mysign.ch<mailto:clemens...@mysign.ch>> 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 <rmannibu...@gmail.com<mailto:rmannibu...@gmail.com>>
Gesendet: Donnerstag, 25. Juli 2019 07:30
An: Tomcat Developers List <dev@tomcat.apache.org<mailto:dev@tomcat.apache.org>>
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:clemens...@mysign.ch<mailto:clemens...@mysign.ch>> 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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