diff --git a/src/main/java/eu/openaire/urls_controller/controllers/UrlController.java b/src/main/java/eu/openaire/urls_controller/controllers/UrlController.java
index 2295c25..f320cd1 100644
--- a/src/main/java/eu/openaire/urls_controller/controllers/UrlController.java
+++ b/src/main/java/eu/openaire/urls_controller/controllers/UrlController.java
@@ -92,12 +92,12 @@ public class UrlController {
             }
         }// end loading-while-loop
 
-        if ( FileUtils.inputScanner != null )
-            FileUtils.inputScanner.close();
+        if ( FileUtils.inputScanner.get() != null ) // Check if the initial value is null.
+            FileUtils.inputScanner.get().close();
 
         Assignment assignment = new Assignment((++assignmentId), tasks, workerId, new Date());
 
-        logger.info("Sending assignment_" + assignment.getAssignmentId() + " with " + tasks.size() + " tasks (" + FileUtils.duplicateIdUrlEntries + " more tasks were discarded as duplicates), to worker with ID: " + workerId);
+        logger.info("Sending assignment_" + assignment.getAssignmentId() + " with " + tasks.size() + " tasks (" + FileUtils.duplicateIdUrlEntries.get() + " more tasks were discarded as duplicates), to worker with ID: " + workerId);
 
         return ResponseEntity.status(200).header("Content-Type", "application/json").body(new AssignmentResponse(assignment));
     }
diff --git a/src/main/java/eu/openaire/urls_controller/util/FileUtils.java b/src/main/java/eu/openaire/urls_controller/util/FileUtils.java
index 13570d7..5715f5f 100644
--- a/src/main/java/eu/openaire/urls_controller/util/FileUtils.java
+++ b/src/main/java/eu/openaire/urls_controller/util/FileUtils.java
@@ -18,14 +18,14 @@ public class FileUtils {
 
     private static final Logger logger = LoggerFactory.getLogger(FileUtils.class);
 
-    public static Scanner inputScanner = null;
-    private static int fileIndex = 0;
-    private static int unretrievableInputLines = 0;
-    public static int duplicateIdUrlEntries = 0;
-    public static int jsonBatchSize = 3000;
+    public static ThreadLocal<Scanner> inputScanner = new ThreadLocal<Scanner>();	// Every Thread has its own variable.
+    private static ThreadLocal<Integer> fileIndex = new ThreadLocal<Integer>();
+    private static ThreadLocal<Integer> unretrievableInputLines = new ThreadLocal<Integer>();
+    public static ThreadLocal<Integer> duplicateIdUrlEntries = new ThreadLocal<Integer>();
+    public static final int jsonBatchSize = 3000;
     private static final String utf8Charset = "UTF-8";
     public static String inputFileFullPath;
-    private static String workingDir = System.getProperty("user.dir") + File.separator;
+    private static final String workingDir = System.getProperty("user.dir") + File.separator;
 
 
     public FileUtils() throws RuntimeException
@@ -39,8 +39,10 @@ public class FileUtils {
 
         logger.debug("Going to retrieve the data from the inputResourceFile: " + resourceFileName);
 
-        FileUtils.inputScanner = new Scanner(inputStream, utf8Charset);
-        fileIndex = 0;  // Re-initialize the file-number-pointer.
+        FileUtils.inputScanner.set(new Scanner(inputStream, utf8Charset));
+        fileIndex.set(0);  // Re-initialize the file-number-pointer.
+        unretrievableInputLines.set(0);
+        duplicateIdUrlEntries.set(0);
     }
 
 
@@ -100,32 +102,32 @@ public class FileUtils {
 
         HashMultimap<String, String> idAndUrlMappedInput = HashMultimap.create(expectedIDsPerBatch, expectedPathsPerID);
 
-        int curBeginning = fileIndex;
+        int curBeginning = fileIndex.get();
 
-        while ( inputScanner.hasNextLine() && (fileIndex < (curBeginning + jsonBatchSize)) )
+        while ( inputScanner.get().hasNextLine() && (fileIndex.get() < (curBeginning + jsonBatchSize)) )
         {// While (!EOF) and inside the current url-batch, iterate through lines.
 
-            //logger.debug("fileIndex: " + FileUtils.fileIndex);	// DEBUG!
+            //logger.debug("fileIndex: " + FileUtils.fileIndex.get());	// DEBUG!
 
             // Take each line, remove potential double quotes.
-            String retrievedLineStr = inputScanner.nextLine();
+            String retrievedLineStr = inputScanner.get().nextLine();
             //logger.debug("Loaded from inputFile: " + retrievedLineStr);	// DEBUG!
 
-            fileIndex ++;
+            fileIndex.set(fileIndex.get() +1);
 
             if ( retrievedLineStr.isEmpty() ) {
-                unretrievableInputLines ++;
+                unretrievableInputLines.set(unretrievableInputLines.get() +1);
                 continue;
             }
 
             if ( (inputIdUrlTuple = jsonDecoder(retrievedLineStr)) == null ) {	// Decode the jsonLine and take the two attributes.
                 logger.warn("A problematic inputLine found: \t" + retrievedLineStr);
-                unretrievableInputLines ++;
+                unretrievableInputLines.set(unretrievableInputLines.get() +1);
                 continue;
             }
 
             if ( !idAndUrlMappedInput.put(inputIdUrlTuple.getId(), inputIdUrlTuple.getUrl()) ) {    // We have a duplicate url in the input.. log it here as we cannot pass it through the HashMultimap. It's possible that this as well as the original might be/give a docUrl.
-                duplicateIdUrlEntries ++;
+                duplicateIdUrlEntries.set(duplicateIdUrlEntries.get() +1);
             }
         }
 
@@ -139,7 +141,7 @@ public class FileUtils {
      */
     public static int getCurrentlyLoadedUrls()	// In the end, it gives the total number of urls we have processed.
     {
-        return FileUtils.fileIndex - FileUtils.unretrievableInputLines;
+        return FileUtils.fileIndex.get() - FileUtils.unretrievableInputLines.get();
     }