From: Vlad Brezae <brezaevlad@gmail.com>
Date: Wed, 12 Apr 2017 22:14:41 +0000 (+0300)
Subject: [sgen] Don't execute jobs before actually starting the workers
X-Git-Url: http://wien.tomnetworks.com/gitweb/?p=mono.git;a=commitdiff_plain;h=f1542c6e52fba916b224dcbe17b750e2b3764e57

[sgen] Don't execute jobs before actually starting the workers

It's counter intuitive and it might lead to races at some point.
---

diff --git a/mono/sgen/sgen-workers.c b/mono/sgen/sgen-workers.c
index 47fb00d9e1f..73691061643 100644
--- a/mono/sgen/sgen-workers.c
+++ b/mono/sgen/sgen-workers.c
@@ -22,6 +22,7 @@
 
 static int workers_num;
 static int active_workers_num;
+static volatile gboolean started;
 static volatile gboolean forced_stop;
 static WorkerData *workers_data;
 static SgenWorkerCallback worker_init_cb;
@@ -313,7 +314,7 @@ should_work_func (void *data_untyped)
 	WorkerData *data = (WorkerData*)data_untyped;
 	int current_worker = (int) (data - workers_data);
 
-	return current_worker < active_workers_num;
+	return started && current_worker < active_workers_num;
 }
 
 static void
@@ -415,6 +416,8 @@ sgen_workers_stop_all_workers (void)
 	sgen_thread_pool_wait_for_all_jobs (pool);
 	sgen_thread_pool_idle_wait (pool);
 	SGEN_ASSERT (0, sgen_workers_all_done (), "Can only signal enqueue work when in no work state");
+
+	started = FALSE;
 }
 
 void
@@ -431,11 +434,14 @@ sgen_workers_set_num_active_workers (int num_workers)
 void
 sgen_workers_start_all_workers (SgenObjectOperations *object_ops_nopar, SgenObjectOperations *object_ops_par, SgenWorkersFinishCallback callback)
 {
+	SGEN_ASSERT (0, !started, "Why are we starting to work without finishing previous cycle");
+
 	idle_func_object_ops_par = object_ops_par;
 	idle_func_object_ops_nopar = object_ops_nopar;
 	forced_stop = FALSE;
 	finish_callback = callback;
 	worker_awakenings = 0;
+	started = TRUE;
 	mono_memory_write_barrier ();
 
 	/*
@@ -461,6 +467,8 @@ sgen_workers_join (void)
 	SGEN_ASSERT (0, sgen_section_gray_queue_is_empty (&workers_distribute_gray_queue), "Why is there still work left to do?");
 	for (i = 0; i < active_workers_num; ++i)
 		SGEN_ASSERT (0, sgen_gray_object_queue_is_empty (&workers_data [i].private_gray_queue), "Why is there still work left to do?");
+
+	started = FALSE;
 }
 
 /*