Merge remote-tracking branch 'origin/topic/awelzel/3190-supervisor-eventmgr-shared-pipe-fix'

* origin/topic/awelzel/3190-supervisor-eventmgr-shared-pipe-fix:
  event: Reinitialize EventMgr's flare after fork() from stem

CHANGES

@@ -1,3 +1,18 @@
+6.2.0-dev.41 | 2023-10-24 19:35:20 +0200
+
+  * GH-3190: event: Reinitialize EventMgr's flare after fork() from stem (Arne Welzel, Corelight)
+
+    Because EventMgr is defined globally as an object (rather than a global
+    pointer to an EventMgr object), its pipe is created even before main()
+    is entered. This further means that in the fork-based supervisor setup,
+    all Zeek processes created from the top-level supervisor process share
+    the same pipe object for the EventMgr. In turn, whenever any of the
+    processes enqueued an event, the flare was fired and ready for reading
+    on all other processes in the cluster, causing much contention and
+    unneeded overhead.
+
+  * btest/Files/mmdb: golang-ci suggested fixes (Arne Welzel, Corelight)
+
 6.2.0-dev.38 | 2023-10-24 13:57:03 +0200
 
   * base/frameworks/spicy: Do not load base/misc/version (Arne Welzel, Corelight)

VERSION

@@ -1 +1 @@
-6.2.0-dev.38
+6.2.0-dev.41

src/Event.cc

@@ -207,4 +207,12 @@ void EventMgr::InitPostScript()
 		reporter->FatalError("Failed to register event manager FD with iosource_mgr");
 	}
 
+void EventMgr::InitPostFork()
+	{
+	// Re-initialize the flare, closing and re-opening the underlying
+	// pipe FDs. This is needed so that each Zeek process in a supervisor
+	// setup has its own pipe instead of them all sharing a single pipe.
+	queue_flare = zeek::detail::Flare{};
+	}
+
 	} // namespace zeek

src/Event.h

@@ -118,6 +118,9 @@ public:
 	const char* Tag() override { return "EventManager"; }
 	void InitPostScript();
 
+	// Initialization to be done after a fork() happened.
+	void InitPostFork();
+
 	uint64_t num_events_queued = 0;
 	uint64_t num_events_dispatched = 0;
 

src/zeek-setup.cc

@@ -554,8 +554,14 @@ SetupResult setup(int argc, char** argv, Options* zopts)
 	auto stem = Supervisor::CreateStem(options.supervisor_mode);
 
 	if ( Supervisor::ThisNode() )
+		{
+		// If we get here, we're a supervised node that just returned
+		// from CreateStem() after being forked from the stem.
 		Supervisor::ThisNode()->Init(&options);
 
+		event_mgr.InitPostFork();
+		}
+
 	script_coverage_mgr.ReadStats();
 
 	auto dns_type = options.dns_mode;