report suppressed exceptions

Author: vladak

opengrok-indexer/src/main/java/org/opengrok/indexer/index/IndexDatabase.java

@@ -1908,6 +1908,11 @@ private void indexParallel(String dir, IndexDownArgs args) throws IndexerExcepti
                                 }
                             }
 
+                            // TODO: debug/test only, REMOVE BEFORE INTEGRATION !!!
+                            if (x.path.contains("a")) {
+                                throw new OutOfMemoryError("fake OOM error");
+                            }
+
                             progress.increment();
                             return x;
                         }

opengrok-indexer/src/main/java/org/opengrok/indexer/index/Indexer.java

@@ -184,7 +184,6 @@ public static int runMain(String[] argv) {
         Executor.registerErrorHandler();
         Set<String> subFilePaths = new HashSet<>(); // absolute paths
         Set<String> subFileArgs = new HashSet<>();  // relative to source root
-        List<Throwable> throwableList = new ArrayList<>();
         int exitCode = 0;
 
         try {
@@ -421,10 +420,22 @@ public static int runMain(String[] argv) {
                 getInstance().sendToConfigHost(env, webappURI);
             }
         } catch (ParseException e) {
+            // This is likely a problem with processing command line arguments, hence print the error to standard
+            // error output.
             System.err.println("** " + e.getMessage());
             exitCode = 1;
         } catch (IndexerException ex) {
-            throwableList.add(ex);
+            // The exception(s) were logged already however it does not hurt to reiterate them
+            // at the very end of indexing (sans the stack trace) since they might have been buried in the log.
+            LOGGER.log(Level.SEVERE, "Indexer failed", ex);
+            int i = 0;
+            if (ex.getSuppressed().length > 0) {
+                LOGGER.log(Level.INFO, "Suppressed exceptions ({0} in total):", ex.getSuppressed().length);
+                for (Throwable throwable : ex.getSuppressed()) {
+                    LOGGER.log(Level.INFO, "{0}: {1}", new Object[]{++i, throwable.getLocalizedMessage()});
+                }
+            }
+            exitCode = 1;
         } catch (Throwable e) {
             LOGGER.log(Level.SEVERE, "Unexpected Exception", e);
             System.err.println("Exception: " + e.getLocalizedMessage());
@@ -440,17 +451,7 @@ public static int runMain(String[] argv) {
             stats.report(LOGGER, "Indexer finished", "indexer.total");
         }
 
-        if (!throwableList.isEmpty()) {
-            // The exception(s) were logged already however it does not hurt to reiterate them
-            // at the very end of indexing (sans the stack trace) since they might have been buried in the log.
-            LOGGER.log(Level.SEVERE, "Indexer finished with {0} exception{1}",
-                    new Object[]{throwableList.size(), throwableList.size() > 1 ? "s" : ""});
-            int i = 0;
-            for (Throwable throwable : throwableList) {
-                LOGGER.log(Level.SEVERE, "{0}: {1}", new Object[]{++i, throwable.getLocalizedMessage()});
-            }
-            exitCode = 1;
-        } else {
+        if (exitCode == 0) {
             LOGGER.log(Level.INFO, "Indexer finished with success");
         }