unit tests: fix DisableMultiManualCompaction in db_compaction_test (#611

)

The test sometimes failed in CI since the test code assumed there was
only 1 bg compaction thread which needed to be blocked but in #194,
the default was changed to 8 so the fix is simply to block all the bg threads.

HISTORY.md

@@ -12,6 +12,7 @@
 * build: Windows compilation fix (#568).
 * Logger: fix Block cache stats trace by spacing it from the last trace (#578).
 * WriteController: move the class to public interface which should have been done under #346.
+* unit tests: fix DBCompactionTest.DisableMultiManualCompaction by blocking all bg compaction threads which increased by default to 8 in #194. 
 
 ## Fig v2.5.0 (06/14/2023)
 Based on RocksDB 8.1.1

db/db_compaction_test.cc

@@ -9100,9 +9100,13 @@ TEST_F(DBCompactionTest, DisableMultiManualCompaction) {
   MoveFilesToLevel(1);
 
   // Block compaction queue
-  test::SleepingBackgroundTask sleeping_task_low;
-  env_->Schedule(&test::SleepingBackgroundTask::DoSleepTask, &sleeping_task_low,
-                 Env::Priority::LOW);
+  std::vector<test::SleepingBackgroundTask> sleeping_task_low(
+      std::max(1, env_->GetBackgroundThreads(Env::Priority::LOW)));
+
+  for (auto& sleeping_task : sleeping_task_low) {
+    env_->Schedule(&test::SleepingBackgroundTask::DoSleepTask, &sleeping_task,
+                   Env::Priority::LOW);
+  }
 
   port::Thread compact_thread1([&]() {
     CompactRangeOptions cro;
@@ -9133,8 +9137,11 @@ TEST_F(DBCompactionTest, DisableMultiManualCompaction) {
   compact_thread1.join();
   compact_thread2.join();
 
-  sleeping_task_low.WakeUp();
-  sleeping_task_low.WaitUntilDone();
+  for (auto& sleeping_task : sleeping_task_low) {
+    sleeping_task.WakeUp();
+    sleeping_task.WaitUntilDone();
+  }
+
   ASSERT_OK(dbfull()->TEST_WaitForCompact());
 }