diff --git a/build-common/src/org/jetbrains/kotlin/incremental/AbstractIncrementalCache.kt b/build-common/src/org/jetbrains/kotlin/incremental/AbstractIncrementalCache.kt
index 337c09af52b..c768fa3a8cb 100644
--- a/build-common/src/org/jetbrains/kotlin/incremental/AbstractIncrementalCache.kt
+++ b/build-common/src/org/jetbrains/kotlin/incremental/AbstractIncrementalCache.kt
@@ -176,8 +176,8 @@ abstract class AbstractIncrementalCache<ClassName>(
     protected class ClassFqNameToSourceMap(
         storageFile: File,
         private val pathConverter: FileToPathConverter
-    ) :
-        BasicStringMap<String>(storageFile, EnumeratorStringDescriptor(), PathStringDescriptor) {
+    ) : BasicStringMap<String>(storageFile, EnumeratorStringDescriptor(), PathStringDescriptor) {
+
         operator fun set(fqName: FqName, sourceFile: File) {
             storage[fqName.asString()] = pathConverter.toPath(sourceFile)
         }
diff --git a/build-common/src/org/jetbrains/kotlin/incremental/IncrementalJvmCache.kt b/build-common/src/org/jetbrains/kotlin/incremental/IncrementalJvmCache.kt
index c5f01e1824b..84d75a417d6 100644
--- a/build-common/src/org/jetbrains/kotlin/incremental/IncrementalJvmCache.kt
+++ b/build-common/src/org/jetbrains/kotlin/incremental/IncrementalJvmCache.kt
@@ -272,6 +272,7 @@ open class IncrementalJvmCache(
 
     private inner class ProtoMap(storageFile: File) : BasicStringMap<ProtoMapValue>(storageFile, ProtoMapValueExternalizer) {
 
+        @Synchronized
         fun process(kotlinClass: LocalFileKotlinClass, changesCollector: ChangesCollector) {
             return put(kotlinClass, changesCollector)
         }
@@ -283,10 +284,12 @@ open class IncrementalJvmCache(
         // from files compiled during last round.
         // However there is no need to compare old and new data in this case
         // (also that would fail with exception).
+        @Synchronized
         fun storeModuleMapping(className: JvmClassName, bytes: ByteArray) {
             storage[className.internalName] = ProtoMapValue(isPackageFacade = false, bytes = bytes, strings = emptyArray())
         }
 
+        @Synchronized
         private fun put(kotlinClass: LocalFileKotlinClass, changesCollector: ChangesCollector) {
             val header = kotlinClass.classHeader
 
@@ -309,6 +312,7 @@ open class IncrementalJvmCache(
         operator fun get(className: JvmClassName): ProtoMapValue? =
             storage[className.internalName]
 
+        @Synchronized
         fun remove(className: JvmClassName, changesCollector: ChangesCollector) {
             val key = className.internalName
             val oldValue = storage[key] ?: return
@@ -325,6 +329,8 @@ open class IncrementalJvmCache(
 
     private inner class JavaSourcesProtoMap(storageFile: File) :
         BasicStringMap<SerializedJavaClass>(storageFile, JavaClassProtoMapValueExternalizer) {
+
+        @Synchronized
         fun process(jvmClassName: JvmClassName, newData: SerializedJavaClass, changesCollector: ChangesCollector) {
             val key = jvmClassName.internalName
             val oldData = storage[key]
@@ -336,6 +342,7 @@ open class IncrementalJvmCache(
             )
         }
 
+        @Synchronized
         fun remove(className: JvmClassName, changesCollector: ChangesCollector) {
             val key = className.internalName
             val oldValue = storage[key] ?: return
@@ -375,6 +382,7 @@ open class IncrementalJvmCache(
         operator fun contains(className: JvmClassName): Boolean =
             className.internalName in storage
 
+        @Synchronized
         fun process(kotlinClass: LocalFileKotlinClass, changesCollector: ChangesCollector) {
             val key = kotlinClass.className.internalName
             val oldMap = storage[key] ?: emptyMap()
@@ -391,6 +399,7 @@ open class IncrementalJvmCache(
             }
         }
 
+        @Synchronized
         fun remove(className: JvmClassName) {
             storage.remove(className.internalName)
         }
@@ -523,6 +532,7 @@ open class IncrementalJvmCache(
             return result
         }
 
+        @Synchronized
         fun process(kotlinClass: LocalFileKotlinClass, changesCollector: ChangesCollector) {
             val key = kotlinClass.className.internalName
             val oldMap = storage[key] ?: emptyMap()
@@ -548,6 +558,7 @@ open class IncrementalJvmCache(
         private fun functionNameBySignature(signature: String): String =
             signature.substringBefore("(")
 
+        @Synchronized
         fun remove(className: JvmClassName) {
             storage.remove(className.internalName)
         }
diff --git a/build-common/src/org/jetbrains/kotlin/incremental/storage/BasicMapsOwner.kt b/build-common/src/org/jetbrains/kotlin/incremental/storage/BasicMapsOwner.kt
index 571f26bb968..57d90607c4f 100644
--- a/build-common/src/org/jetbrains/kotlin/incremental/storage/BasicMapsOwner.kt
+++ b/build-common/src/org/jetbrains/kotlin/incremental/storage/BasicMapsOwner.kt
@@ -30,6 +30,7 @@ open class BasicMapsOwner(val cachesDir: File) {
     protected val String.storageFile: File
         get() = File(cachesDir, this + "." + CACHE_EXTENSION)
 
+    @Synchronized
     protected fun <K, V, M : BasicMap<K, V>> registerMap(map: M): M {
         maps.add(map)
         return map
@@ -47,6 +48,7 @@ open class BasicMapsOwner(val cachesDir: File) {
         forEachMapSafe("flush") { it.flush(memoryCachesOnly) }
     }
 
+    @Synchronized
     private fun forEachMapSafe(actionName: String, action: (BasicMap<*, *>) -> Unit) {
         val actionExceptions = LinkedHashMap<String, Exception>()
         maps.forEach {
@@ -66,5 +68,6 @@ open class BasicMapsOwner(val cachesDir: File) {
     }
 
     @TestOnly
+    @Synchronized
     fun dump(): String = maps.joinToString("\n\n") { it.dump() }
 }
\ No newline at end of file
diff --git a/build-common/src/org/jetbrains/kotlin/incremental/storage/CachingLazyStorage.kt b/build-common/src/org/jetbrains/kotlin/incremental/storage/CachingLazyStorage.kt
index 360a4e517b1..7e4a25c2ada 100644
--- a/build-common/src/org/jetbrains/kotlin/incremental/storage/CachingLazyStorage.kt
+++ b/build-common/src/org/jetbrains/kotlin/incremental/storage/CachingLazyStorage.kt
@@ -17,9 +17,11 @@
 package org.jetbrains.kotlin.incremental.storage
 
 import com.intellij.util.io.DataExternalizer
+import com.intellij.util.io.IOUtil
 import com.intellij.util.io.KeyDescriptor
 import com.intellij.util.io.PersistentHashMap
 import java.io.File
+import java.io.IOException
 
 
 /**
@@ -30,7 +32,6 @@ class CachingLazyStorage<K, V>(
     private val keyDescriptor: KeyDescriptor<K>,
     private val valueExternalizer: DataExternalizer<V>
 ) : LazyStorage<K, V> {
-    @Volatile
     private var storage: PersistentHashMap<K, V>? = null
 
     @Synchronized
@@ -80,8 +81,10 @@ class CachingLazyStorage<K, V>(
         try {
             storage?.close()
         } finally {
-            PersistentHashMap.deleteFilesStartingWith(storageFile)
             storage = null
+            if (!IOUtil.deleteAllFilesStartingWith(storageFile)) {
+                throw IOException("Could not delete internal storage: ${storageFile.absolutePath}")
+            }
         }
     }
 
diff --git a/build-common/src/org/jetbrains/kotlin/incremental/storage/ClassOneToManyMap.kt b/build-common/src/org/jetbrains/kotlin/incremental/storage/ClassOneToManyMap.kt
index 6549c96224a..f06524591b6 100644
--- a/build-common/src/org/jetbrains/kotlin/incremental/storage/ClassOneToManyMap.kt
+++ b/build-common/src/org/jetbrains/kotlin/incremental/storage/ClassOneToManyMap.kt
@@ -20,18 +20,18 @@ import org.jetbrains.kotlin.incremental.dumpCollection
 import org.jetbrains.kotlin.name.FqName
 import java.io.File
 
-internal open class ClassOneToManyMap(
-        storageFile: File
-) : BasicStringMap<Collection<String>>(storageFile, StringCollectionExternalizer) {
+internal open class ClassOneToManyMap(storageFile: File) : BasicStringMap<Collection<String>>(storageFile, StringCollectionExternalizer) {
     override fun dumpValue(value: Collection<String>): String = value.dumpCollection()
 
+    @Synchronized
     fun add(key: FqName, value: FqName) {
         storage.append(key.asString(), listOf(value.asString()))
     }
 
     operator fun get(key: FqName): Collection<FqName> =
-            storage[key.asString()]?.map(::FqName) ?: setOf()
+        storage[key.asString()]?.map(::FqName) ?: setOf()
 
+    @Synchronized
     operator fun set(key: FqName, values: Collection<FqName>) {
         if (values.isEmpty()) {
             remove(key)
@@ -41,10 +41,14 @@ internal open class ClassOneToManyMap(
         storage[key.asString()] = values.map(FqName::asString)
     }
 
+    @Synchronized
     fun remove(key: FqName) {
         storage.remove(key.asString())
     }
 
+    // Access to caches could be done from multiple threads (e.g. JPS worker and RMI). The underlying collection is already synchronized,
+    // thus we need synchronization of this method and all modification methods.
+    @Synchronized
     fun removeValues(key: FqName, removed: Set<FqName>) {
         val notRemoved = this[key].filter { it !in removed }
         this[key] = notRemoved
diff --git a/build-common/src/org/jetbrains/kotlin/incremental/storage/NonCachingLazyStorage.kt b/build-common/src/org/jetbrains/kotlin/incremental/storage/NonCachingLazyStorage.kt
index 614426e0b1e..755ea8262ec 100644
--- a/build-common/src/org/jetbrains/kotlin/incremental/storage/NonCachingLazyStorage.kt
+++ b/build-common/src/org/jetbrains/kotlin/incremental/storage/NonCachingLazyStorage.kt
@@ -17,9 +17,11 @@
 package org.jetbrains.kotlin.incremental.storage
 
 import com.intellij.util.io.DataExternalizer
+import com.intellij.util.io.IOUtil
 import com.intellij.util.io.KeyDescriptor
 import com.intellij.util.io.PersistentHashMap
 import java.io.File
+import java.io.IOException
 
 
 class NonCachingLazyStorage<K, V>(
@@ -27,7 +29,6 @@ class NonCachingLazyStorage<K, V>(
     private val keyDescriptor: KeyDescriptor<K>,
     private val valueExternalizer: DataExternalizer<V>
 ) : LazyStorage<K, V> {
-    @Volatile
     private var storage: PersistentHashMap<K, V>? = null
 
     @Synchronized
@@ -76,11 +77,12 @@ class NonCachingLazyStorage<K, V>(
     override fun clean() {
         try {
             storage?.close()
-        } catch (ignored: Throwable) {
+        } finally {
+            storage = null
+            if (!IOUtil.deleteAllFilesStartingWith(storageFile)) {
+                throw IOException("Could not delete internal storage: ${storageFile.absolutePath}")
+            }
         }
-
-        PersistentHashMap.deleteFilesStartingWith(storageFile)
-        storage = null
     }
 
     @Synchronized
diff --git a/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalCachesManager.kt b/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalCachesManager.kt
index c529463ac24..83c8bb1f881 100644
--- a/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalCachesManager.kt
+++ b/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalCachesManager.kt
@@ -30,7 +30,12 @@ abstract class IncrementalCachesManager<PlatformCache : AbstractIncrementalCache
 ) {
     val pathConverter = IncrementalFileToPathConverter(rootProjectDir)
     private val caches = arrayListOf<BasicMapsOwner>()
+
+    var isClosed = false
+
+    @Synchronized
     protected fun <T : BasicMapsOwner> T.registerCache() {
+        assert(!isClosed) { "Attempted to add new cache into closed storage." }
         caches.add(this)
     }
 
@@ -41,9 +46,12 @@ abstract class IncrementalCachesManager<PlatformCache : AbstractIncrementalCache
     val lookupCache: LookupStorage = LookupStorage(lookupCacheDir, pathConverter).apply { registerCache() }
     abstract val platformCache: PlatformCache
 
+    @Synchronized
     fun close(flush: Boolean = false): Boolean {
+        if (isClosed) {
+            return true
+        }
         var successful = true
-
         for (cache in caches) {
             if (flush) {
                 try {
@@ -62,6 +70,7 @@ abstract class IncrementalCachesManager<PlatformCache : AbstractIncrementalCache
             }
         }
 
+        isClosed = true
         return successful
     }
 }
diff --git a/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalCompilerRunner.kt b/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalCompilerRunner.kt
index 450e25eb3d3..f8d44d2b79e 100644
--- a/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalCompilerRunner.kt
+++ b/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalCompilerRunner.kt
@@ -37,6 +37,7 @@ import org.jetbrains.kotlin.incremental.util.BufferingMessageCollector
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.progress.CompilationCanceledStatus
 import java.io.File
+import java.io.IOException
 import java.util.*
 
 abstract class IncrementalCompilerRunner<
@@ -97,7 +98,10 @@ abstract class IncrementalCompilerRunner<
             val allKotlinFiles = allSourceFiles.filter { it.isKotlinFile(kotlinSourceFilesExtensions) }
             return compileIncrementally(args, caches, allKotlinFiles, CompilationMode.Rebuild(reason), messageCollector)
         }
-
+        // attempt IC
+        // if OK or failed compilation - return
+        // internal error - clear
+        // failed to close - clear
         return try {
             val changedFiles = providedChangedFiles ?: caches.inputsCache.sourceSnapshotMap.compareAndUpdate(allSourceFiles)
             val compilationMode = sourcesToCompile(caches, changedFiles, args, messageCollector)
@@ -143,8 +147,8 @@ abstract class IncrementalCompilerRunner<
             }
         }
 
-        assert(!destinationDir.exists()) { "Could not delete destination dir $destinationDir" }
-        assert(!workingDir.exists()) { "Could not delete caches dir $workingDir" }
+        if (destinationDir.exists()) throw IOException("Could not delete directory $destinationDir.")
+        if (workingDir.exists()) throw IOException("Could not delete internal caches in folder $workingDir")
         destinationDir.mkdirs()
         workingDir.mkdirs()
     }
diff --git a/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/snapshots/FileSnapshotMap.kt b/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/snapshots/FileSnapshotMap.kt
index 5996de96e4e..1db484b6346 100644
--- a/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/snapshots/FileSnapshotMap.kt
+++ b/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/snapshots/FileSnapshotMap.kt
@@ -26,6 +26,7 @@ class FileSnapshotMap(storageFile: File) : BasicStringMap<FileSnapshot>(storageF
     override fun dumpValue(value: FileSnapshot): String =
         value.toString()
 
+    @Synchronized
     fun compareAndUpdate(newFiles: Iterable<File>): ChangedFiles.Known {
         val snapshotProvider = SimpleFileSnapshotProviderImpl()
         val newOrModified = ArrayList<File>()
diff --git a/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/storage/SourceToOutputFilesMap.kt b/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/storage/SourceToOutputFilesMap.kt
index 18448f56799..28032db9d44 100644
--- a/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/storage/SourceToOutputFilesMap.kt
+++ b/compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/storage/SourceToOutputFilesMap.kt
@@ -12,6 +12,7 @@ class SourceToOutputFilesMap(
     storageFile: File
 ) : BasicStringMap<Collection<String>>(storageFile, PathStringDescriptor, StringCollectionExternalizer) {
 
+    @Synchronized
     operator fun set(sourceFile: File, outputFiles: Collection<File>) {
         storage[sourceFile.absolutePath] = outputFiles.map { it.absolutePath }
     }
@@ -22,6 +23,7 @@ class SourceToOutputFilesMap(
     override fun dumpValue(value: Collection<String>) =
         value.dumpCollection()
 
+    @Synchronized
     fun remove(file: File): Collection<File> =
         get(file).also { storage.remove(file.absolutePath) }
 }
\ No newline at end of file