diff --git a/jps/jps-builders/src/org/jetbrains/jps/incremental/artifacts/IncArtifactBuilder.java b/jps/jps-builders/src/org/jetbrains/jps/incremental/artifacts/IncArtifactBuilder.java
index 45db7706f0e1..2d002c98f441 100644
--- a/jps/jps-builders/src/org/jetbrains/jps/incremental/artifacts/IncArtifactBuilder.java
+++ b/jps/jps-builders/src/org/jetbrains/jps/incremental/artifacts/IncArtifactBuilder.java
@@ -15,6 +15,7 @@
  */
 package org.jetbrains.jps.incremental.artifacts;
 
+import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.util.Pair;
 import com.intellij.openapi.util.io.FileUtil;
 import com.intellij.openapi.util.text.StringUtil;
@@ -47,6 +48,7 @@ import java.util.*;
  * @author nik
  */
 public class IncArtifactBuilder extends TargetBuilder<ArtifactRootDescriptor, ArtifactBuildTarget> {
+  private static final Logger LOG = Logger.getInstance(IncArtifactBuilder.class);
   public static final String BUILDER_NAME = "Artifacts builder";
 
   public IncArtifactBuilder() {
@@ -77,7 +79,10 @@ public class IncArtifactBuilder extends TargetBuilder<ArtifactRootDescriptor, Ar
     try {
       final Collection<String> deletedFiles = holder.getRemovedFiles(target);
 
-      context.processMessage(new ProgressMessage("Building artifact '" + artifact.getName() + "'..."));
+      String messageText = "Building artifact '" + artifact.getName() + "'...";
+      context.processMessage(new ProgressMessage(messageText));
+      LOG.debug(messageText);
+
       runArtifactTasks(context, target.getArtifact(), ArtifactBuildTaskProvider.ArtifactBuildPhase.PRE_PROCESSING);
       final SourceToOutputMapping srcOutMapping = pd.dataManager.getSourceToOutputMap(target);
       final ArtifactOutputToSourceMapping outSrcMapping = pd.dataManager.getStorage(target, ArtifactOutToSourceStorageProvider.INSTANCE);
@@ -143,6 +148,9 @@ public class IncArtifactBuilder extends TargetBuilder<ArtifactRootDescriptor, Ar
 
         for (String sourcePath : sourcePaths) {
           if (!descriptor.getFilter().shouldBeCopied(sourcePath, pd)) {
+            if (LOG.isDebugEnabled()) {
+              LOG.debug("File " + sourcePath + " will be skipped because it isn't accepted by filter");
+            }
             continue;
           }
           DestinationInfo destination = descriptor.getDestinationInfo();
@@ -217,6 +225,9 @@ public class IncArtifactBuilder extends TargetBuilder<ArtifactRootDescriptor, Ar
       }
 
       if (deleted) {
+        if (LOG.isDebugEnabled()) {
+          LOG.debug("Outdated output file deleted: " + filePath);
+        }
         outSrcMapping.remove(filePath);
         deletedPaths.add(filePath);
         for (String sourcePath : filesToDelete.get(filePath)) {
diff --git a/jps/jps-builders/src/org/jetbrains/jps/incremental/artifacts/instructions/FileBasedArtifactRootDescriptor.java b/jps/jps-builders/src/org/jetbrains/jps/incremental/artifacts/instructions/FileBasedArtifactRootDescriptor.java
index ee42cc4da78b..8ddf30bad6e7 100644
--- a/jps/jps-builders/src/org/jetbrains/jps/incremental/artifacts/instructions/FileBasedArtifactRootDescriptor.java
+++ b/jps/jps-builders/src/org/jetbrains/jps/incremental/artifacts/instructions/FileBasedArtifactRootDescriptor.java
@@ -15,6 +15,7 @@
  */
 package org.jetbrains.jps.incremental.artifacts.instructions;
 
+import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.util.io.FileUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jps.builders.BuildOutputConsumer;
@@ -34,6 +35,7 @@ import java.util.Collections;
  * @author nik
  */
 public class FileBasedArtifactRootDescriptor extends ArtifactRootDescriptor {
+  private static final Logger LOG = Logger.getInstance(FileBasedArtifactRootDescriptor.class);
   public FileBasedArtifactRootDescriptor(@NotNull File file,
                                          @NotNull SourceFileFilter filter,
                                          int index,
@@ -79,6 +81,9 @@ public class FileBasedArtifactRootDescriptor extends ArtifactRootDescriptor {
       FileUtil.copyContent(file, targetFile);
       outputConsumer.registerOutputFile(targetFile, Collections.singletonList(filePath));
     }
+    else if (LOG.isDebugEnabled()) {
+      LOG.debug("Target path " + targetPath + " is already registered so " + filePath + " won't be copied");
+    }
     outSrcMapping.appendData(targetPath, Collections.singletonList(new ArtifactOutputToSourceMapping.SourcePathAndRootIndex(filePath, rootIndex)));
   }
 }