From 60aebc247ecd9fae8d676705422db8f282c2b590 Mon Sep 17 00:00:00 2001
From: NianJiuZst <3235467914@qq.com>
Date: Sat, 5 Sep 2026 00:14:08 +0800
Subject: [PATCH] servlet: Register response trailers before stream writes

Register the trailer supplier while creating the servlet stream, before a peer reset can cause the container to commit the response. This removes the race where Jetty throws IllegalStateException from writeHeaders after receiving RST_STREAM.

Fixes #12777
---
 servlet/src/main/java/io/grpc/servlet/ServletServerStream.java | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/servlet/src/main/java/io/grpc/servlet/ServletServerStream.java b/servlet/src/main/java/io/grpc/servlet/ServletServerStream.java
index 0182f302698..63415f87472 100644
--- a/servlet/src/main/java/io/grpc/servlet/ServletServerStream.java
+++ b/servlet/src/main/java/io/grpc/servlet/ServletServerStream.java
@@ -82,6 +82,8 @@ final class ServletServerStream extends AbstractServerStream {
     this.resp = (HttpServletResponse) asyncCtx.getResponse();
     this.writer = new AsyncServletOutputStreamWriter(
         asyncCtx, transportState, logId);
+    // Register before the peer can reset the stream and cause the container to commit the response.
+    resp.setTrailerFields(sink.trailerSupplier);
     resp.getOutputStream().setWriteListener(new GrpcWriteListener());
   }
 
@@ -231,7 +233,6 @@ private final class Sink implements AbstractServerStream.Sink {
     @Override
     public void writeHeaders(Metadata headers, boolean flush) {
       writeHeadersToServletResponse(headers);
-      resp.setTrailerFields(trailerSupplier);
       try {
         writer.flush();
       } catch (IOException e) {