diff --git a/java/execution/impl/src/com/intellij/execution/AlternativeSdkRootsProvider.kt b/java/execution/impl/src/com/intellij/execution/AlternativeSdkRootsProvider.kt
index 97e3c661029c..aa2164618758 100644
--- a/java/execution/impl/src/com/intellij/execution/AlternativeSdkRootsProvider.kt
+++ b/java/execution/impl/src/com/intellij/execution/AlternativeSdkRootsProvider.kt
@@ -12,6 +12,7 @@ import com.intellij.openapi.roots.OrderRootType
 import com.intellij.openapi.roots.SyntheticLibrary
 import com.intellij.openapi.roots.ex.ProjectRootManagerEx
 import com.intellij.openapi.util.EmptyRunnable
+import com.intellij.openapi.util.Key
 import com.intellij.openapi.util.registry.Registry
 import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.ui.AppUIUtil
@@ -40,16 +41,21 @@ class AlternativeSdkRootsProvider : AdditionalLibraryRootsProvider() {
   }
 
   companion object {
-    private val storedLibs = mutableListOf<SyntheticLibrary>()
+    private val ALTERNATIVE_SDK_LIBS_KEY = Key.create<Collection<SyntheticLibrary>>("ALTERNATIVE_SDK_LIBS_KEY")
 
     @JvmStatic
     fun reindexIfNeeded(project: Project) {
       if (!Registry.`is`("index.run.configuration.jre")) return
-      val provider = AdditionalLibraryRootsProvider.EP_NAME.findExtension(AlternativeSdkRootsProvider::class.java)!!
+      val provider = EP_NAME.findExtension(AlternativeSdkRootsProvider::class.java)!!
       val additionalProjectLibraries = provider.getAdditionalProjectLibraries(project)
-      if (additionalProjectLibraries != storedLibs) {
-        storedLibs.clear()
-        storedLibs.addAll(additionalProjectLibraries)
+      val update = synchronized(ALTERNATIVE_SDK_LIBS_KEY) {
+        val res = additionalProjectLibraries != project.getUserData(ALTERNATIVE_SDK_LIBS_KEY)
+        if (res) {
+          project.putUserData(ALTERNATIVE_SDK_LIBS_KEY, additionalProjectLibraries)
+        }
+        res
+      }
+      if (update) {
         AppUIUtil.invokeOnEdt {
           WriteAction.run<RuntimeException> {
             ProjectRootManagerEx.getInstanceEx(project).makeRootsChange(EmptyRunnable.getInstance(), false, true)