From 12b99eda89c75491f56039c4ae7d6e0f8b08bc4d Mon Sep 17 00:00:00 2001
From: Noah Hilverling <noah.hilverling@icinga.com>
Date: Thu, 9 Dec 2021 14:47:35 +0100
Subject: [PATCH] Make sure Redis connection pool is large enough

The default Redis PoolSize is 10 * CPU, which isn't enough to run Icinga DB on machines with only 1 CPU.
Most of our open connections come from blocking XREADs. (e.g. Heartbeat, Runtime, Overdue, History)
---
 pkg/config/redis.go | 2 ++
 pkg/utils/utils.go  | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/pkg/config/redis.go b/pkg/config/redis.go
index 259d87f8..bd3c7c05 100644
--- a/pkg/config/redis.go
+++ b/pkg/config/redis.go
@@ -8,6 +8,7 @@ import (
 	"github.com/icinga/icingadb/pkg/icingaredis"
 	"github.com/icinga/icingadb/pkg/logging"
 	"github.com/icinga/icingadb/pkg/retry"
+	"github.com/icinga/icingadb/pkg/utils"
 	"github.com/pkg/errors"
 	"go.uber.org/zap"
 	"net"
@@ -54,6 +55,7 @@ func (r *Redis) NewClient(logger *logging.Logger) (*icingaredis.Client, error) {
 
 	opts := c.Options()
 	opts.MaxRetries = opts.PoolSize + 1 // https://github.com/go-redis/redis/issues/1737
+	opts.PoolSize = utils.MaxInt(32, opts.PoolSize)
 	c = redis.NewClient(opts)
 
 	return icingaredis.NewClient(c, logger, &r.Options), nil
diff --git a/pkg/utils/utils.go b/pkg/utils/utils.go
index 6c8b4fff..91ed99a5 100644
--- a/pkg/utils/utils.go
+++ b/pkg/utils/utils.go
@@ -191,3 +191,12 @@ func AppName() string {
 
 	return filepath.Base(exe)
 }
+
+// MaxInt returns the larger of the given integers.
+func MaxInt(x, y int) int {
+	if x > y {
+		return x
+	}
+
+	return y
+}