following IDEA-CR-8206 (IDEA-151182)

platform/lang-impl/src/com/intellij/codeInsight/documentation/DocumentationManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2015 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -1172,18 +1172,14 @@ public class DocumentationManager extends DockablePopupManager<DocumentationComp
       }
 
       final Ref<String> result = new Ref<String>();
-      long deadline = System.currentTimeMillis() + DOC_GENERATION_TIMEOUT_MILLISECONDS;
-      while (!ProgressIndicatorUtils.runInReadActionWithWriteActionPriority(new Runnable() {
+      ProgressIndicatorUtils.runInReadActionWithWriteActionPriorityWithRetries(new Runnable() {
           @Override
           public void run() {
             final SmartPsiElementPointer originalElement = myElement.getUserData(ORIGINAL_ELEMENT_KEY);
             String doc = provider.generateDoc(myElement, originalElement != null ? originalElement.getElement() : null);
             result.set(doc);
           }
-        }) && System.currentTimeMillis() < deadline) {
-        //noinspection BusyWait
-        Thread.sleep(DOC_GENERATION_PAUSE_MILLISECONDS);
-      }
+        }, DOC_GENERATION_TIMEOUT_MILLISECONDS, DOC_GENERATION_PAUSE_MILLISECONDS);
       return result.get();
     }
 

platform/lang-impl/src/com/intellij/codeInsight/documentation/QuickDocOnMouseOverManager.java

@@ -295,12 +295,14 @@ public class QuickDocOnMouseOverManager {
     @Override
     public void run() {
       Ref<PsiElement> targetElementRef = new Ref<>();
-      ProgressIndicatorUtils.runInReadActionWithWriteActionPriority(new Runnable() {
+      ProgressIndicatorUtils.runInReadActionWithWriteActionPriorityWithRetries(new Runnable() {
         @Override
         public void run() {
-          targetElementRef.set(docManager.findTargetElement(editor, offset, originalElement.getContainingFile(), originalElement));
+          if (originalElement.isValid()) {
+            targetElementRef.set(docManager.findTargetElement(editor, offset, originalElement.getContainingFile(), originalElement));
+          }
         }
-      });
+      }, 5000, 100);
       ApplicationManager.getApplication().invokeLater(new Runnable() {
         @Override
         public void run() {

platform/platform-impl/src/com/intellij/openapi/progress/util/ProgressIndicatorUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2015 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,6 +31,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.ide.PooledThreadExecutor;
 
 import java.util.concurrent.Executor;
+import java.util.concurrent.locks.LockSupport;
 
 /**
  * Methods in this class are used to equip long background processes which take read actions with a special listener
@@ -66,9 +67,30 @@ public class ProgressIndicatorUtils {
     scheduleWithWriteActionPriority(progressIndicator, PooledThreadExecutor.INSTANCE, readTask);
   }
 
+  /**
+   * Repeatedly tries to run given task in read action without blocking write actions (for this to work effectively the action should invoke 
+   * {@link ProgressManager#checkCanceled()} or {@link ProgressIndicator#checkCanceled()} often enough).
+   * 
+   * @param action task to run
+   * @param timeout timeout in milliseconds 
+   * @param pauseBetweenRetries pause between retries in milliseconds 
+   * @return <code>true</code> if the action succeeded to run without interruptions, <code>false</code> otherwise 
+   * @throws InterruptedException if execution was interrupted while waiting for the next attempt
+   */
+  public static boolean runInReadActionWithWriteActionPriorityWithRetries(@NotNull final Runnable action, 
+                                                                          long timeout, long pauseBetweenRetries) {
+    boolean result;
+    long deadline = System.currentTimeMillis() + timeout;
+    while (!(result = runInReadActionWithWriteActionPriority(action)) && System.currentTimeMillis() < deadline) {
+      LockSupport.parkNanos(pauseBetweenRetries * 1000);
+    }
+    return result;
+  }
+
   /**
    * This method attempts to run provided action synchronously in a read action, so that, if possible, it wouldn't impact any pending, 
-   * executing or future write actions. 
+   * executing or future write actions (for this to work effectively the action should invoke {@link ProgressManager#checkCanceled()} or 
+   * {@link ProgressIndicator#checkCanceled()} often enough). 
    * It returns <code>true</code> if action was executed successfully. It returns <code>false</code> if the action was not
    * executed successfully, i.e. if:
    * <ul>