From 47c6bfc528897a49763034737b19ffe46bf89514 Mon Sep 17 00:00:00 2001
From: Elizaveta Shashkova <Elizaveta.Shashkova@jetbrains.com>
Date: Mon, 5 Oct 2015 15:37:32 +0300
Subject: [PATCH] Add read action (EA-73866)

---
 .../com/jetbrains/python/debugger/PyStackFrame.java | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/python/src/com/jetbrains/python/debugger/PyStackFrame.java b/python/src/com/jetbrains/python/debugger/PyStackFrame.java
index 4ada2e7fc112..97a6e5673952 100644
--- a/python/src/com/jetbrains/python/debugger/PyStackFrame.java
+++ b/python/src/com/jetbrains/python/debugger/PyStackFrame.java
@@ -16,6 +16,7 @@
 package com.jetbrains.python.debugger;
 
 import com.intellij.icons.AllIcons;
+import com.intellij.openapi.application.AccessToken;
 import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.editor.Document;
@@ -80,9 +81,15 @@ public class PyStackFrame extends XStackFrame {
 
     boolean isExternal = true;
     final VirtualFile file = myPosition.getFile();
-    final Document document = FileDocumentManager.getInstance().getDocument(file);
-    if (document != null) {
-      isExternal = !ProjectRootManager.getInstance(myProject).getFileIndex().isInContent(file);
+    AccessToken lock = ApplicationManager.getApplication().acquireReadActionLock();
+    try {
+      final Document document = FileDocumentManager.getInstance().getDocument(file);
+      if (document != null) {
+        isExternal = !ProjectRootManager.getInstance(myProject).getFileIndex().isInContent(file);
+      }
+    }
+    finally {
+      lock.finish();
     }
 
     component.append(myFrameInfo.getName(), gray(SimpleTextAttributes.REGULAR_ATTRIBUTES, isExternal));