Do not trigger background compilation while top level parsing in mutator thread

runtime/vm/compiler.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/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/block_scheduler.h"
@@ skipping 1736 matching lines @@
     ASSERT(result);
     {
       Thread* thread = Thread::Current();
       StackZone stack_zone(thread);
       Zone* zone = stack_zone.GetZone();
       HANDLESCOPE(thread);
       Function& function = Function::Handle(zone);
       { MonitorLocker ml(queue_monitor_);
         function = function_queue()->PeekFunction();
       }
-      while (running_ && !function.IsNull()) {
+      while (running_ && !function.IsNull() && !isolate_->IsTopLevelParsing()) {
         // Check that we have aggregated and cleared the stats.
         ASSERT(thread->compiler_stats()->IsCleared());
         const Error& error = Error::Handle(zone,
             Compiler::CompileOptimizedFunction(thread,
                                                function,
                                                Compiler::kNoOSRDeoptId));
         // TODO(srdjan): We do not expect errors while compiling optimized
         // code, any errors should have been caught when compiling
         // unoptimized code. Any issues while optimizing are flagged by
         // making the result invalid.
@@ skipping 19 matching lines @@
         }
         if (qelem != NULL) {
           delete qelem;
         }
       }
     }
     Thread::ExitIsolateAsHelper();
     {
       // Wait to be notified when the work queue is not empty.
       MonitorLocker ml(queue_monitor_);
-      while (function_queue()->IsEmpty() && running_) {
+      while ((function_queue()->IsEmpty() || isolate_->IsTopLevelParsing())
+              && running_) {
         ml.Wait();
       }
     }
   }  // while running
 
   {
     // Notify that the thread is done.
     MonitorLocker ml_done(done_monitor_);
     *done_ = true;
     ml_done.Notify();
@@ skipping 193 matching lines @@
 }
 
 
 void BackgroundCompiler::EnsureInit(Thread* thread) {
   UNREACHABLE();
 }
 
 #endif  // DART_PRECOMPILED_RUNTIME
 
 }  // namespace dart