Fix for issue 27380 - VM stuck in deadlock with background finalization and background compiler thr…

runtime/vm/heap.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/heap.h"
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/flags.h"
 #include "vm/isolate.h"
@@ skipping 71 matching lines @@
 
 uword Heap::AllocateOld(intptr_t size, HeapPage::PageType type) {
   ASSERT(Thread::Current()->no_safepoint_scope_depth() == 0);
   uword addr = old_space_.TryAllocate(size, type);
   if (addr != 0) {
     return addr;
   }
   // If we are in the process of running a sweep, wait for the sweeper to free
   // memory.
   Thread* thread = Thread::Current();
-  {
-    MonitorLocker ml(old_space_.tasks_lock());
-    addr = old_space_.TryAllocate(size, type);
-    while ((addr == 0) && (old_space_.tasks() > 0)) {
-      ml.WaitWithSafepointCheck(thread);
+  if (thread->CanCollectGarbage()) {
+    {
+      MonitorLocker ml(old_space_.tasks_lock());
       addr = old_space_.TryAllocate(size, type);
+      while ((addr == 0) && (old_space_.tasks() > 0)) {
+        ml.WaitWithSafepointCheck(thread);
+        addr = old_space_.TryAllocate(size, type);
+      }
     }
-  }
-  if (addr != 0) {
-    return addr;
-  }
-  if (thread->CanCollectGarbage()) {
+    if (addr != 0) {
+      return addr;
+    }
     // All GC tasks finished without allocating successfully. Run a full GC.
     CollectAllGarbage();
     addr = old_space_.TryAllocate(size, type);
     if (addr != 0) {
       return addr;
     }
     // Wait for all of the concurrent tasks to finish before giving up.
     {
       MonitorLocker ml(old_space_.tasks_lock());
       addr = old_space_.TryAllocate(size, type);
@@ skipping 747 matching lines @@
   Dart::vm_isolate()->heap()->WriteProtect(false);
 }
 
 
 WritableVMIsolateScope::~WritableVMIsolateScope() {
   ASSERT(Dart::vm_isolate()->heap()->UsedInWords(Heap::kNew) == 0);
   Dart::vm_isolate()->heap()->WriteProtect(true);
 }
 
 }  // namespace dart