Dynamically update classloader after adding a library with the add-library command #25153
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Dynamically updates the common classloader if a common library is added.
| * @throws UnsupportedOperationException If adding not supported by the classloader | ||
| */ | ||
| public void addToClassPath(URL url) { | ||
| if (commonClassLoader != null) { |
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Just invert the condition, == null should be first.
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Is it possible also to remove the library? I see there is the |
| public String getCommonClassPath() { | ||
| return commonClassPath; | ||
| } | ||
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| private static String urlsToClassPath(Stream<URL> urls) { |
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What a great candidate to have unit test for!
| return urls | ||
| .map(URL::getFile) | ||
| .filter(Predicate.not(String::isBlank)) | ||
| .map(file -> new File(file).getAbsolutePath()) |
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Could the lambda be replaced with additional .map?
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You mean have 2 map calls instead of just one? It could but I thought it’s an unnecessary overhead to call map twice.
Perhaps, on Linux (and Unix generally) library file will be removed, but library will be accessible until server stop/restart. On Windows |
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The remove-library command just deletes the JAR on the file system. It could remove the url in the classloader but it’s not necessary. The CL will just ignore the url if the file doesn’t exist. So no need to remove the url from the CL. Classes loaded from the removed JAR will keep being loaded even after the JAR is removed. |
If JAR was already opened by CL, CL will not ignore this JAR. Application will load classes and resources from this JAR. |
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We already have this command, so it should probably do more, ie. refuse to remove the file if it is used by any classloader and report that classloader to the user. We can try to do that in another PR, but for this reason I always pushed libraries inside ear/war files, because they have lifecycle while this is quite fragile. Could it be enough to disable the application and then remove the library? Maybe we can move this to discussions. |
Dynamically updates the common classloader if a common library is added. It means that restart is not needed to add the library to the classpath.