From 514db35cf81adb3539d1ab564da58934b192b8bc Mon Sep 17 00:00:00 2001
From: Blottiere Paul <blottiere.paul@gmail.com>
Date: Thu, 18 Oct 2018 14:01:03 +0100
Subject: [PATCH] Fixes freeze of server during rendering

---
 src/server/services/wms/qgsmaprendererjobproxy.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/server/services/wms/qgsmaprendererjobproxy.cpp b/src/server/services/wms/qgsmaprendererjobproxy.cpp
index a321f0fe97d..b7df6176c83 100644
--- a/src/server/services/wms/qgsmaprendererjobproxy.cpp
+++ b/src/server/services/wms/qgsmaprendererjobproxy.cpp
@@ -56,6 +56,13 @@ namespace QgsWms
       renderJob.setFeatureFilterProvider( mFeatureFilterProvider );
 #endif
       renderJob.start();
+
+      // Allows the main thread to manage blocking call coming from rendering
+      // threads (see discussion in #18988).
+      QEventLoop loop;
+      QObject::connect( &renderJob, &QgsMapRendererParallelJob::finished, &loop, &QEventLoop::quit );
+      loop.exec();
+
       renderJob.waitForFinished();
       *image = renderJob.renderedImage();
       mPainter.reset( new QPainter( image ) );