C0urante commented on code in PR #13971:
URL: https://github.com/apache/kafka/pull/13971#discussion_r1267238592
##########
connect/runtime/src/main/java/org/apache/kafka/connect/runtime/isolation/PluginScanner.java:
##########
@@ -118,35 +120,80 @@ private void loadJdbcDrivers(final ClassLoader loader) {
}
@SuppressWarnings({"rawtypes", "unchecked"})
- protected <T> PluginDesc<T> pluginDesc(Class<? extends T> plugin, String
version, ClassLoader loader) {
- return new PluginDesc(plugin, version, loader);
+ protected <T> PluginDesc<T> pluginDesc(Class<? extends T> plugin, String
version, PluginSource source) {
+ return new PluginDesc(plugin, version, source.loader());
}
@SuppressWarnings("unchecked")
- protected <T> SortedSet<PluginDesc<T>> getServiceLoaderPluginDesc(Class<T>
klass, ClassLoader loader) {
+ protected <T> SortedSet<PluginDesc<T>> getServiceLoaderPluginDesc(Class<T>
klass, PluginSource source) {
SortedSet<PluginDesc<T>> result = new TreeSet<>();
- ServiceLoader<T> serviceLoader = ServiceLoader.load(klass, loader);
- for (Iterator<T> iterator = serviceLoader.iterator();
iterator.hasNext(); ) {
- try (LoaderSwap loaderSwap = withClassLoader(loader)) {
+ ServiceLoader<T> serviceLoader = handleLinkageError(klass, source, ()
-> ServiceLoader.load(klass, source.loader()));
+ Iterator<T> iterator = handleLinkageError(klass, source,
serviceLoader::iterator);
+ while (handleLinkageError(klass, source, iterator::hasNext)) {
+ try (LoaderSwap loaderSwap = withClassLoader(source.loader())) {
T pluginImpl;
try {
- pluginImpl = iterator.next();
+ pluginImpl = handleLinkageError(klass, source,
iterator::next);
} catch (ServiceConfigurationError t) {
- log.error("Failed to discover {}{}",
klass.getSimpleName(), reflectiveErrorDescription(t.getCause()), t);
+ log.error("Failed to discover {} in {}{}",
+ klass.getSimpleName(), source.location(),
reflectiveErrorDescription(t.getCause()), t);
continue;
}
Class<? extends T> pluginKlass = (Class<? extends T>)
pluginImpl.getClass();
- if (pluginKlass.getClassLoader() != loader) {
+ if (pluginKlass.getClassLoader() != source.loader()) {
log.debug("{} from other classloader {} is visible from
{}, excluding to prevent isolated loading",
- pluginKlass.getSimpleName(),
pluginKlass.getClassLoader(), loader);
+ pluginKlass.getSimpleName(),
pluginKlass.getClassLoader(), source.location());
continue;
}
- result.add(pluginDesc(pluginKlass, versionFor(pluginImpl),
loader));
+ result.add(pluginDesc(pluginKlass, versionFor(pluginImpl),
source));
}
}
return result;
}
+ /**
+ * Helper to evaluate a {@link ServiceLoader} operation while handling
{@link LinkageError}s.
+ *
+ * @param klass The plugin superclass which is being loaded
+ * @param function A function on a {@link ServiceLoader} which may throw
{@link LinkageError}
+ * @return the return value of function
+ * @throws Error errors thrown by the passed-in function
+ * @param <T> Type being iterated over by the ServiceLoader
+ * @param <U> Return value of the passed-in function
+ */
+ private <T, U> U handleLinkageError(Class<T> klass, PluginSource source,
Supplier<U> function) {
+ // It's difficult to know for sure if the iterator was able to advance
past the first broken
+ // plugin class, or if it will continue to fail on that broken class
for any subsequent calls
+ // to Iterator::hasNext or Iterator::next
+ // For reference, see https://bugs.openjdk.org/browse/JDK-8196182,
which describes
+ // the behavior we are trying to mitigate with this logic as buggy,
but indicates that a fix
+ // in the JDK standard library ServiceLoader implementation is
unlikely to land
+ LinkageError lastError = null;
+ // Try a fixed maximum number of times in case the ServiceLoader
cannot move past a faulty plugin,
+ // but the LinkageError varies between calls. This limit is chosen to
be higher than the typical number
+ // of plugins in a single plugin location, and to limit the amount of
log-spam on startup.
+ for (int i = 0; i < 100; i++) {
+ try {
+ return function.get();
+ } catch (LinkageError t) {
+ // As an optimization, hide subsequent error logs if two
consecutive errors look similar.
+ // This reduces log-spam for iterators which cannot advance
and rethrow the same exception.
+ if (lastError == null
+ || !Objects.equals(lastError.getClass(), t.getClass())
+ || !Objects.equals(lastError.getMessage(),
t.getMessage())) {
+ log.error("Failed to discover {} in {}{}",
+ klass.getSimpleName(), source.location(),
reflectiveErrorDescription(t.getCause()), t);
+ }
+ lastError = t;
+ }
+ }
+ log.error("Received excessive ServiceLoader errors: assuming the
runtime ServiceLoader implementation cannot " +
+ "skip faulty implementations. Use a different JRE,
resolve errors for all {} in {}, or " +
+ "disable service loader scanning.",
Review Comment:
Great catch, thanks!
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