From 1c33b5937ea252e1ea5bd8830dc1ec1d583b8da6 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Tue, 11 Jun 2019 01:02:56 +0300
Subject: [PATCH] app/vmselect/promql: prevent from `count_values` explosion of
 timeseries, which could result in OOM

---
 app/vmselect/promql/aggr.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/app/vmselect/promql/aggr.go b/app/vmselect/promql/aggr.go
index 8f6d5a7a7..bce21a095 100644
--- a/app/vmselect/promql/aggr.go
+++ b/app/vmselect/promql/aggr.go
@@ -100,10 +100,18 @@ func aggrFuncExt(afe func(tss []*timeseries) []*timeseries, argOrig []*timeserie
 	}
 	bbPool.Put(bb)
 
+	srcTssCount := 0
+	dstTssCount := 0
 	rvs := make([]*timeseries, 0, len(m))
 	for _, tss := range m {
 		rv := afe(tss)
 		rvs = append(rvs, rv...)
+		srcTssCount += len(tss)
+		dstTssCount += len(rv)
+		if dstTssCount > 2000 && dstTssCount > 16*srcTssCount {
+			// This looks like count_values explosion.
+			return nil, fmt.Errorf(`too many timeseries after aggragation; got %d; want less than %d`, dstTssCount, 16*srcTssCount)
+		}
 	}
 	return rvs, nil
 }