From bf72397b9ffd6b133a176d2a539f4116014a78e5 Mon Sep 17 00:00:00 2001
From: Mathias Arlaud <mathias.arlaud@gmail.com>
Date: Thu, 24 Apr 2025 08:52:37 +0200
Subject: [PATCH] [HttpFoundation] Flush after each echo in `StreamedResponse`

---
 src/Symfony/Component/HttpFoundation/StreamedResponse.php | 2 ++
 .../HttpFoundation/Tests/StreamedResponseTest.php         | 8 ++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/Symfony/Component/HttpFoundation/StreamedResponse.php b/src/Symfony/Component/HttpFoundation/StreamedResponse.php
index 6eedf1c49d2e8..4e755a7cdf07f 100644
--- a/src/Symfony/Component/HttpFoundation/StreamedResponse.php
+++ b/src/Symfony/Component/HttpFoundation/StreamedResponse.php
@@ -56,6 +56,8 @@ public function setChunks(iterable $chunks): static
         $this->callback = static function () use ($chunks): void {
             foreach ($chunks as $chunk) {
                 echo $chunk;
+                @ob_flush();
+                flush();
             }
         };
 
diff --git a/src/Symfony/Component/HttpFoundation/Tests/StreamedResponseTest.php b/src/Symfony/Component/HttpFoundation/Tests/StreamedResponseTest.php
index 2a8fe582501a6..fdaee3a35ff6f 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/StreamedResponseTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/StreamedResponseTest.php
@@ -30,10 +30,14 @@ public function testConstructorWithChunks()
         $chunks = ['foo', 'bar', 'baz'];
         $callback = (new StreamedResponse($chunks))->getCallback();
 
-        ob_start();
+        $buffer = '';
+        ob_start(function (string $chunk) use (&$buffer) {
+            $buffer .= $chunk;
+        });
         $callback();
 
-        $this->assertSame('foobarbaz', ob_get_clean());
+        ob_get_clean();
+        $this->assertSame('foobarbaz', $buffer);
     }
 
     public function testPrepareWith11Protocol()