Merge branch '1.1.x'

spring-boot/src/main/java/org/springframework/boot/context/web/ErrorPageFilter.java

@@ -112,7 +112,7 @@ class ErrorPageFilter extends AbstractConfigurableEmbeddedServletContainer imple
 				handleErrorStatus(request, response, status, wrapped.getMessage());
 				response.flushBuffer();
 			}
-			else if (!request.isAsyncStarted()) {
+			else if (!request.isAsyncStarted() && !response.isCommitted()) {
 				response.flushBuffer();
 			}
 		}
@@ -184,7 +184,7 @@ class ErrorPageFilter extends AbstractConfigurableEmbeddedServletContainer imple
 				+ request.getRequestURI() + " as the response has already been"
 				+ " committed. As a result, the response may have the wrong status"
 				+ " code. If your application is running on WebSphere Application"
-				+ " Server you may be able to resolve this problem by setting "
+				+ " Server you may be able to resolve this problem by setting"
 				+ " com.ibm.ws.webcontainer.invokeFlushAfterService to false";
 		if (ex == null) {
 			logger.error(message);

spring-boot/src/test/java/org/springframework/boot/context/web/ErrorPageFilterTests.java

@@ -40,6 +40,10 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 
 /**
  * Tests for {@link ErrorPageFilter}.
@@ -343,4 +347,16 @@ public class ErrorPageFilterTests {
 		assertTrue(this.response.isCommitted());
 	}
 
+	@Test
+	public void responseIsNotFlushedIfStatusIsLessThan400AndItHasAlreadyBeenCommitted()
+			throws Exception {
+		HttpServletResponse committedResponse = mock(HttpServletResponse.class);
+		given(committedResponse.isCommitted()).willReturn(true);
+		given(committedResponse.getStatus()).willReturn(200);
+
+		this.filter.doFilter(this.request, committedResponse, this.chain);
+
+		verify(committedResponse, times(0)).flushBuffer();
+	}
+
 }