adding comment

sqlitecluster/SQLiteNode.cpp

@@ -1716,7 +1716,10 @@ void SQLiteNode::_onMESSAGE(SQLitePeer* peer, const SData& message) {
                     uint64_t threadAttemptStartTimestamp = STimeNow();
                     thread(&SQLiteNode::_replicate, this, peer, message, _dbPool->getIndex(false), threadAttemptStartTimestamp).detach();
                 } catch (const system_error& e) {
-
+                    // If the server is strugling and falling behind on replication, we might have too many threads
+                    // causing a resource exhaustion. If that happens, all the transations that are already threaded
+                    // and waiting for the transaction that failed will be stuck in an infinite loop. To prevent that
+                    // we're cancelling all threads that would need to wait on the transaction that is failing.
                     uint64_t cancelAfter = message.calcU64("NewCount") - 1;
                     _localCommitNotifier.cancel(cancelAfter);
                     _leaderCommitNotifier.cancel(cancelAfter);