cluster_mutex = it->second.get();
  }

  profiler->RegisterExecution(function);

  string human_signature;
  if (VLOG_IS_ON(2)) {
    human_signature = VLOG_IS_ON(3) ? signature.HumanString() : function.name();
    VLOG(2) << "DeviceCompilationClusterSignature: " << human_signature;
  }

  // Acquire the cache entry lock and compile, if necessary.