diff --git a/language/duchain/duchain.cpp b/language/duchain/duchain.cpp
--- a/language/duchain/duchain.cpp
+++ b/language/duchain/duchain.cpp
@@ -286,7 +286,7 @@
           //Just to make sure the cache is cleared periodically
           ModificationRevisionSet::clearCache();
 
-          m_data->doMoreCleanup(SOFT_CLEANUP_STEPS);
+          m_data->doMoreCleanup(SOFT_CLEANUP_STEPS, true, true);
           if(m_stopRunning)
             break;
         }
@@ -684,7 +684,7 @@
   ///doing the cleanup without permanently locking the du-chain. During these steps the consistency
   ///of the disk-storage is not guaranteed, but only few changes will be done during these steps,
   ///so the final step where the duchain is permanently locked is much faster.
-  void doMoreCleanup(int retries = 0, bool needLockRepository = true) {
+  void doMoreCleanup(int retries = 0, bool needLockRepository = true, bool tryLock = false) {
 
     if(m_cleanupDisabled)
       return;
@@ -697,25 +697,32 @@
 
     Q_ASSERT(!instance->lock()->currentThreadHasReadLock() && !instance->lock()->currentThreadHasWriteLock());
     DUChainWriteLocker writeLock(instance->lock());
-    PersistentSymbolTable::self().clearCache();
 
     //This is used to stop all parsing before starting to do the cleanup. This way less happens during the
     //soft cleanups, and we have a good chance that during the "hard" cleanup only few data has to be written.
-    QList<ILanguageSupport*> lockedParseMutexes;
-
     QList<QReadWriteLock*> locked;
 
     if(needLockRepository) {
-
+      QList<ILanguageSupport*> languages;
       if (ICore* core = ICore::self())
         if (ILanguageController* lc = core->languageController())
-          lockedParseMutexes = lc->loadedLanguages();
+          languages = lc->loadedLanguages();
 
       writeLock.unlock();
 
       //Here we wait for all parsing-threads to stop their processing
-      foreach(const auto language, lockedParseMutexes) {
-        language->parseLock()->lockForWrite();
+      foreach(const auto language, languages) {
+        if (tryLock) {
+          if (!language->parseLock()->tryLockForWrite()) {
+            // some language is still parsing, don't interfere with the cleanup
+            foreach(auto* lock, locked) {
+              lock->unlock();
+            }
+            return;
+          }
+        } else {
+          language->parseLock()->lockForWrite();
+        }
         locked << language->parseLock();
       }
 
@@ -726,6 +733,7 @@
     }
 
     QTime startTime = QTime::currentTime();
+    PersistentSymbolTable::self().clearCache();
 
     storeAllInformation(!retries, writeLock); //Puts environment-information into a repository