diff --git a/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/AlgorithmFailedException.java b/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/AlgorithmFailedException.java
new file mode 100644
index 00000000..9c1bce30
--- /dev/null
+++ b/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/AlgorithmFailedException.java
@@ -0,0 +1,7 @@
+package org.jetbrains.research.groups.ml_methods.algorithm;
+
+class AlgorithmFailedException extends RuntimeException {
+    AlgorithmFailedException(String message) {
+        super(message);
+    }
+}
diff --git a/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/AlgorithmResult.java b/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/AlgorithmResult.java
index 1d8785df..3aae08ef 100644
--- a/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/AlgorithmResult.java
+++ b/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/AlgorithmResult.java
@@ -7,6 +7,7 @@
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 
 public class AlgorithmResult {
     private final List<CalculatedRefactoring> refactorings;
@@ -25,7 +26,7 @@ public class AlgorithmResult {
     }
 
     AlgorithmResult(AlgorithmType algorithmType, @NotNull Exception exception) {
-        this.refactorings = Collections.emptyList();
+        this.refactorings = null;
         this.algorithmType = algorithmType;
         this.executionTime = 0;
         this.threadUsed = 0;
@@ -33,7 +34,8 @@ public class AlgorithmResult {
     }
 
     public List<CalculatedRefactoring> getRefactorings() {
-        return Collections.unmodifiableList(refactorings);
+        throwIfNotSuccess();
+        return Collections.unmodifiableList(Objects.requireNonNull(refactorings));
     }
 
     public AlgorithmType getAlgorithmType() {
@@ -41,10 +43,12 @@ public AlgorithmType getAlgorithmType() {
     }
 
     public long getExecutionTime() {
+        throwIfNotSuccess();
         return executionTime;
     }
 
     public int getThreadUsed() {
+        throwIfNotSuccess();
         return threadUsed;
     }
 
@@ -53,14 +57,21 @@ public Exception getException() {
         return exception;
     }
 
-    public boolean isSuccess() {
+    boolean isSuccess() {
         return exception == null;
     }
 
-    public String getReport() {
-        return "Results of " + algorithmType + " running" + System.lineSeparator() +
-                "  Found " + refactorings.size() + " refactorings" + System.lineSeparator() +
+    private void throwIfNotSuccess() {
+        if (!isSuccess()) {
+            throw new AlgorithmFailedException("Algorithm ended with exception. Requested data cannot be retrieved.");
+        }
+    }
+
+    String getReport() {
+        return isSuccess() ? "Results of " + algorithmType + " running" + System.lineSeparator() +
+                "  Found " + Objects.requireNonNull(refactorings).size() + " refactorings" + System.lineSeparator() +
                 "  Execution time: " + executionTime + System.lineSeparator() +
-                "  Threads used: " + threadUsed;
+                "  Threads used: " + threadUsed :
+                algorithmType + " failed with exception: " + Objects.requireNonNull(exception).getMessage();
     }
 }
diff --git a/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/HAC.java b/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/HAC.java
index ca969190..0e0ca6e4 100755
--- a/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/HAC.java
+++ b/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/HAC.java
@@ -19,6 +19,7 @@
 
 import java.util.*;
 import java.util.Map.Entry;
+import java.util.concurrent.ExecutorService;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Stream;
 
@@ -26,6 +27,9 @@
 
 public class HAC extends AbstractAlgorithm {
     private static final Logger LOGGER = Logging.getLogger(HAC.class);
+    private static final int MAX_NUMBER_OF_CLASSES = 1000;
+    private static final int MAX_NUMBER_OF_METHODS = 3000;
+    private static final int MAX_NUMBER_OF_FIELDS = 1500;
     private static final double ACCURACY = 1;
 
     private static final @NotNull DistanceCalculator distanceCalculator = RelevanceBasedDistanceCalculator.getInstance();
@@ -44,6 +48,23 @@ public HAC() {
         return new HACExecutor();
     }
 
+    @NotNull
+    @Override
+    public AlgorithmResult execute(@NotNull AttributesStorage attributes, @Nullable ExecutorService service, boolean enableFieldRefactorings) {
+        if (willHaveLongTimeExecution(attributes)) {
+            LOGGER.warn("HAC haven't been executed because project is too large and HAC will work too long");
+            return new AlgorithmResult(AlgorithmType.HAC,
+                    new TooLargeProjectException("HAC execution will be too long on this project"));
+        }
+        return super.execute(attributes, service, enableFieldRefactorings);
+    }
+
+    private boolean willHaveLongTimeExecution(@NotNull AttributesStorage attributes) {
+        return attributes.getClassesAttributes().size() > MAX_NUMBER_OF_CLASSES ||
+                attributes.getMethodsAttributes().size() > MAX_NUMBER_OF_METHODS ||
+                attributes.getFieldsAttributes().size() > MAX_NUMBER_OF_FIELDS;
+    }
+
     private static class HACExecutor implements Executor {
         private final SortedSet<Triple> heap = new TreeSet<>();
         private final Map<Long, Triple> triples = new HashMap<>();
diff --git a/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/RefactoringExecutionContext.java b/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/RefactoringExecutionContext.java
index df04bc67..f9d92eab 100644
--- a/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/RefactoringExecutionContext.java
+++ b/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/RefactoringExecutionContext.java
@@ -150,7 +150,9 @@ private void calculate(Algorithm algorithm) {
         final AlgorithmResult result =
             algorithm.execute(attributes, executorService, enableFieldRefactoring);
 
-        algorithmsResults.add(result);
+        if (result.isSuccess()) {
+            algorithmsResults.add(result);
+        }
     }
 
     public List<AlgorithmResult> getAlgorithmResults() {
diff --git a/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/TooLargeProjectException.java b/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/TooLargeProjectException.java
new file mode 100644
index 00000000..86f6f6b4
--- /dev/null
+++ b/core/src/main/java/org/jetbrains/research/groups/ml_methods/algorithm/TooLargeProjectException.java
@@ -0,0 +1,7 @@
+package org.jetbrains.research.groups.ml_methods.algorithm;
+
+class TooLargeProjectException extends Exception {
+    TooLargeProjectException(String message) {
+        super(message);
+    }
+}