diff --git a/src/main/java/org/aksw/iguana/cc/worker/impl/SPARQLProtocolWorker.java b/src/main/java/org/aksw/iguana/cc/worker/impl/SPARQLProtocolWorker.java
index 7576b6d56..5c5b72a6b 100644
--- a/src/main/java/org/aksw/iguana/cc/worker/impl/SPARQLProtocolWorker.java
+++ b/src/main/java/org/aksw/iguana/cc/worker/impl/SPARQLProtocolWorker.java
@@ -164,8 +164,8 @@ public boolean successful() {
     }
 
 
-    private final HttpClient httpClient;
-    private final ExecutorService executor;
+    private HttpClient httpClient;
+    private final ThreadPoolExecutor executor;
 
     private final XXHashFactory hasherFactory = XXHashFactory.fastestJavaInstance();
     private final RequestFactory requestFactory;
@@ -178,22 +178,18 @@ public boolean successful() {
     // used to read the http response body
     private byte[] buffer = new byte[4096];
 
-
+    @Override
     public Config config() {
-        return (Config) config;
+        return (SPARQLProtocolWorker.Config) config;
     }
 
 
     public SPARQLProtocolWorker(long workerId, ResponseBodyProcessor responseBodyProcessor, Config config) {
         super(workerId, responseBodyProcessor, config);
         this.responseBodyProcessor = responseBodyProcessor;
-        this.executor = Executors.newFixedThreadPool(2);
+        this.executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(1);
         this.requestFactory = new RequestFactory(config().requestType());
-        this.httpClient = HttpClient.newBuilder()
-                .executor(this.executor)
-                .followRedirects(HttpClient.Redirect.ALWAYS)
-                .connectTimeout(config().timeout())
-                .build();
+        this.httpClient = buildHttpClient();
     }
 
 
@@ -224,10 +220,10 @@ public CompletableFuture<Result> start() {
                     }
                 }
             } catch (IOException | URISyntaxException e) {
-                throw new RuntimeException(e);
+                throw new RuntimeException(e); // TODO: better error handling
             }
 
-            return new Result(this.workerId, executionStats);
+            return new Result(this.workerID, executionStats);
         }, executor);
     }
 
@@ -237,7 +233,7 @@ private ExecutionStats executeQuery(Duration timeout, boolean discardOnFailure)
         if (result.response().isPresent())
             statuscode = Optional.of(result.response().get().statusCode());
 
-        if (result.successful()) { // 2xx
+        if (result.successful() && this.config.parseResults()) { // 2xx
             // process result
             if (!responseBodyProcessor.add(result.actualContentLength().getAsLong(), result.hash().getAsLong(), result.outputStream().get())) {
                 this.responseBodybbaos = result.outputStream().get();
@@ -245,6 +241,7 @@ private ExecutionStats executeQuery(Duration timeout, boolean discardOnFailure)
                 this.responseBodybbaos = new BigByteArrayOutputStream();
             }
         }
+        this.responseBodybbaos.reset();
 
         if (!result.completed() && discardOnFailure) {
             return null;
@@ -271,6 +268,11 @@ private HttpExecutionResult executeHttpRequest(Duration timeout) throws IOExcept
                 config().acceptHeader()
         );
 
+        if (((ThreadPoolExecutor) this.httpClient.executor().get()).getActiveCount() != 0) {
+            ((ThreadPoolExecutor) this.httpClient.executor().get()).shutdownNow();
+            this.httpClient = buildHttpClient();
+        }
+
         final Instant requestStart = Instant.now();
         BiFunction<HttpResponse<InputStream>, Exception, HttpExecutionResult> createFailedResult = (response, e) -> {
             final Duration requestDuration = Duration.between(requestStart, Instant.now());
@@ -295,6 +297,9 @@ private HttpExecutionResult executeHttpRequest(Duration timeout) throws IOExcept
                                 try (var hasher = hasherFactory.newStreamingHash64(0)) {
                                     int readBytes;
                                     while ((readBytes = bodyStream.readNBytes(this.buffer, 0, this.buffer.length)) != 0) {
+                                        if (Duration.between(requestStart, requestStart.plus(timeout)).isNegative()) {
+                                            return createFailedResult.apply(httpResponse, new TimeoutException());
+                                        }
                                         hasher.update(this.buffer, 0, readBytes);
                                         this.responseBodybbaos.write(this.buffer, 0, readBytes);
                                     }
@@ -302,7 +307,7 @@ private HttpExecutionResult executeHttpRequest(Duration timeout) throws IOExcept
                                     if (contentLength.isPresent() &&
                                             (this.responseBodybbaos.size() < contentLength.getAsLong() ||
                                              this.responseBodybbaos.size() > contentLength.getAsLong())) {
-                                        return createFailedResult.apply(httpResponse, null); // TODO: custom exception maybe?
+                                        return createFailedResult.apply(httpResponse, new ProtocolException("Content-Length header value doesn't match actual content length."));
                                     }
 
                                     return new HttpExecutionResult(
@@ -328,4 +333,12 @@ private HttpExecutionResult executeHttpRequest(Duration timeout) throws IOExcept
             return createFailedResult.apply(null, e);
         }
     }
+
+    private HttpClient buildHttpClient() {
+        return HttpClient.newBuilder()
+                .executor(Executors.newFixedThreadPool(1))
+                .followRedirects(HttpClient.Redirect.ALWAYS)
+                .connectTimeout(config().timeout())
+                .build();
+    }
 }