From 2da44a820373aefa1bfb2b7963fee1fe16a0b87a Mon Sep 17 00:00:00 2001
From: nik <Nikolay.Chashnikov@jetbrains.com>
Date: Thu, 16 Feb 2017 16:17:30 +0300
Subject: [PATCH] FileDownloader: fixed concurrency problem (EA-95126)

---
 .../com/intellij/util/download/impl/FileDownloaderImpl.java  | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/platform/lang-impl/src/com/intellij/util/download/impl/FileDownloaderImpl.java b/platform/lang-impl/src/com/intellij/util/download/impl/FileDownloaderImpl.java
index 3bbb7c2d0ecc..7fb758a4ac97 100644
--- a/platform/lang-impl/src/com/intellij/util/download/impl/FileDownloaderImpl.java
+++ b/platform/lang-impl/src/com/intellij/util/download/impl/FileDownloaderImpl.java
@@ -49,6 +49,7 @@ import javax.swing.*;
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
@@ -149,8 +150,8 @@ public class FileDownloaderImpl implements FileDownloader {
   @NotNull
   @Override
   public List<Pair<File, DownloadableFileDescription>> download(@NotNull final File targetDir) throws IOException {
-    final List<Pair<File, DownloadableFileDescription>> downloadedFiles = new ArrayList<>();
-    final List<Pair<File, DownloadableFileDescription>> existingFiles = new ArrayList<>();
+    List<Pair<File, DownloadableFileDescription>> downloadedFiles = Collections.synchronizedList(new ArrayList<>());
+    List<Pair<File, DownloadableFileDescription>> existingFiles = Collections.synchronizedList(new ArrayList<>());
     ProgressIndicator parentIndicator = ProgressManager.getInstance().getProgressIndicator();
     if (parentIndicator == null) {
       parentIndicator = new EmptyProgressIndicator();