Github user chinmaykolhatkar commented on a diff in the pull request:
https://github.com/apache/incubator-apex-core/pull/208#discussion_r51119455
--- Diff: engine/src/main/java/com/datatorrent/stram/StramLocalCluster.java
---
@@ -318,6 +333,21 @@ public StramLocalCluster(LogicalPlan dag) throws
IOException, ClassNotFoundExcep
}
}
+ private void addExtraJarsToClasspath(Set<String> jars)
+ throws InvocationTargetException, IllegalAccessException,
MalformedURLException, NoSuchMethodException
+ {
+ List<URL> jarUrls = new LinkedList<>();
+ for (String jarPath : jars) {
+ File file = new File(jarPath);
+ URL url = file.toURI().toURL();
+ jarUrls.add(url);
+ }
+
+ ClassLoader prevCl = Thread.currentThread().getContextClassLoader();
+ ClassLoader urlCl = URLClassLoader.newInstance(jarUrls.toArray(new
URL[jarUrls.size()]), prevCl);
+ Thread.currentThread().setContextClassLoader(urlCl);
--- End diff --
Thomas can answer this question better. But here is additional information
as per my understanding:
The place where Constructor of StramLocalCluster is called is a common
point where both code paths joins.
But there is a slight difference in how the operators are loaded by these 2
paths.
In LocalMode.runApp, the operator classes are already part of the System
class loader. This is because when ApplicationTest is launched the operators
are already in classpath provided by maven.
StreamAppLauncher.runLocal is invoked by an application launched from dtcli
(a java process). dtcli do not have operators present in its system classpath.
Hence, in StramAppLauncher.runLocal (dtcli -local), there is a context
class loader created which has information about operator classes. This context
classloader is later used to load the operator classes.
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