1 files changed, 24 insertions, 4 deletions
diff --git a/src/thirdparty/unrar/threadmisc.cpp b/src/thirdparty/unrar/threadmisc.cpp
index d56867be4..4ad5af2e5 100644
--- a/src/thirdparty/unrar/threadmisc.cpp
+++ b/src/thirdparty/unrar/threadmisc.cpp
@@ -58,6 +58,18 @@ ThreadPool* CreateThreadPool()
   if (GlobalPoolUseCount++ == 0)
     GlobalPool=new ThreadPool(MaxPoolThreads);
 
+  // We use a simple thread pool, which does not allow to add tasks from
+  // different functions and threads in the same time. It is ok for RAR,
+  // but UnRAR.dll can be used in multithreaded environment. So if one of
+  // threads requests a copy of global pool and another copy is already
+  // in use, we create and return a new pool instead of existing global.
+  if (GlobalPoolUseCount > 1)
+  {
+    ThreadPool *Pool = new ThreadPool(MaxPoolThreads);
+    CriticalSectionEnd(&PoolCreateSync.CritSection); 
+    return Pool;
+  }
+
   CriticalSectionEnd(&PoolCreateSync.CritSection); 
   return GlobalPool;
 }
@@ -65,12 +77,20 @@ ThreadPool* CreateThreadPool()
 
 void DestroyThreadPool(ThreadPool *Pool)
 {
-  CriticalSectionStart(&PoolCreateSync.CritSection); 
+  if (Pool!=NULL)
+  {
+    CriticalSectionStart(&PoolCreateSync.CritSection); 
 
-  if (Pool!=NULL && Pool==GlobalPool && GlobalPoolUseCount > 0 && --GlobalPoolUseCount == 0)
-    delete GlobalPool;
+    if (Pool==GlobalPool && GlobalPoolUseCount > 0 && --GlobalPoolUseCount == 0)
+      delete GlobalPool;
 
-  CriticalSectionEnd(&PoolCreateSync.CritSection); 
+    // To correctly work in multithreaded environment UnRAR.dll creates
+    // new pools if global pool is already in use. We delete such pools here.
+    if (Pool!=GlobalPool)
+      delete Pool;
+
+    CriticalSectionEnd(&PoolCreateSync.CritSection); 
+  }
 }