Stablize executor_test (#4774)

Use less GPU memory

paddle/framework/executor_test.cc

@@ -17,6 +17,7 @@ limitations under the License. */
 #include <memory>
 #include <vector>
 
+#include "gflags/gflags.h"
 #include "gtest/gtest.h"
 #include "paddle/framework/attribute.h"
 #include "paddle/framework/backward.h"
@@ -317,3 +318,12 @@ TEST_F(ExecutorTesterFeedAndFetch, GPU) {
   }
 }
 #endif
+
+DECLARE_double(fraction_of_gpu_memory_to_use);
+
+int main(int argc, char** argv) {
+  testing::InitGoogleTest(&argc, argv);
+  // Use less GPU memory for unittest.
+  FLAGS_fraction_of_gpu_memory_to_use = 0.25;
+  return RUN_ALL_TESTS();
+}