Fix for SIGSEGV crash when using passenger with OOBGC. The least busy

process selection method was only suitable for enabled processes, and
not disabling/disabled processes. Closes GH-1469.

CHANGELOG

@@ -1,3 +1,9 @@
+Release 5.0.8
+-------------
+
+ * Fixes a Passenger crash (SIGSEGV) that occurs occasionally when out-of-band garbage collection is enabled. Closes GH-1469.
+
+
 Release 5.0.7
 -------------
 

ext/common/ApplicationPool2/Group.h

@@ -389,7 +389,7 @@ class Group: public boost::enable_shared_from_this<Group> {
 	RouteResult route(const Options &options) const {
 		if (OXT_LIKELY(enabledCount > 0)) {
 			if (options.stickySessionId == 0) {
-				Process *process = findProcessWithLowestBusyness(enabledProcesses);
+				Process *process = findEnabledProcessWithLowestBusyness();
 				if (process->canBeRoutedTo()) {
 					return RouteResult(process);
 				} else {
@@ -496,6 +496,29 @@ class Group: public boost::enable_shared_from_this<Group> {
 			return NULL;
 		}
 
+		int lowestBusyness = -1;
+		Process *leastBusyProcess = NULL;
+		ProcessList::const_iterator it;
+		ProcessList::const_iterator end = processes.end();
+		for (it = processes.begin(); it != end; it++) {
+			Process *process = (*it).get();
+			int busyness = process->busyness();
+			if (lowestBusyness == -1 || lowestBusyness > busyness) {
+				lowestBusyness = busyness;
+				leastBusyProcess = process;
+			}
+		}
+		return leastBusyProcess;
+	}
+
+	/**
+	 * Cache-optimized version of findProcessWithLowestBusyness() for the common case.
+	 */
+	Process *findEnabledProcessWithLowestBusyness() const {
+		if (enabledProcesses.empty()) {
+			return NULL;
+		}
+
 		int leastBusyProcessIndex = -1;
 		int lowestBusyness = 0;
 		unsigned int i, size = enabledProcessBusynessLevels.size();
@@ -1006,8 +1029,7 @@ class Group: public boost::enable_shared_from_this<Group> {
 			assert(m_spawning || restarting() || poolAtFullCapacity());
 
 			if (disablingCount > 0 && !restarting()) {
-				Process *process = findProcessWithLowestBusyness(
-					disablingProcesses);
+				Process *process = findProcessWithLowestBusyness(disablingProcesses);
 				assert(process != NULL);
 				if (!process->isTotallyBusy()) {
 					return newSession(process, newOptions.currentTime);