Fix hang when encoding with GPU enabled but not working.

2 files changed, 15 insertions, 7 deletions

diff --git a/src/lib/grok_j2k_encoder_thread.cc b/src/lib/grok_j2k_encoder_thread.cc
index 6975d9221..e6c256f11 100644
--- a/src/lib/grok_j2k_encoder_thread.cc
+++ b/src/lib/grok_j2k_encoder_thread.cc
@@ -67,6 +67,8 @@ try
 		if (_context->launch(frame, grok.selected) && _context->scheduleCompress(frame)) {
 			frame_guard.cancel();
 		}
+
+		boost::this_thread::interruption_point();
 	}
 }
 catch (boost::thread_interrupted& e)
diff --git a/src/lib/j2k_encoder.cc b/src/lib/j2k_encoder.cc
index b416f921d..3aaaa4e76 100644
--- a/src/lib/j2k_encoder.cc
+++ b/src/lib/j2k_encoder.cc
@@ -475,13 +475,19 @@ J2KEncoder::retry(DCPVideo video)
 {
 #ifdef DCPOMATIC_GROK
 	{
-		boost::mutex::scoped_lock lock(_threads_mutex);
-		auto is_grok_thread_with_errors = [](shared_ptr<const J2KEncoderThread> thread) {
-			auto grok = dynamic_pointer_cast<const GrokJ2KEncoderThread>(thread);
-			return grok && grok->errors();
-		};
-
-		_give_up = std::any_of(_threads.begin(), _threads.end(), is_grok_thread_with_errors);
+		/* We might be destroying or remaking these threads, and hopefully in that case we'll come back here
+		 * to check again; we definitely don't want to block in that case waiting to be allowed to check
+		 * _threads.
+		 */
+		boost::mutex::scoped_lock lock(_threads_mutex, boost::try_to_lock);
+		if (lock) {
+			auto is_grok_thread_with_errors = [](shared_ptr<const J2KEncoderThread> thread) {
+				auto grok = dynamic_pointer_cast<const GrokJ2KEncoderThread>(thread);
+				return grok && grok->errors();
+			};
+
+			_give_up = std::any_of(_threads.begin(), _threads.end(), is_grok_thread_with_errors);
+		}
 	}
 #endif