From fce4fda3a7bcb4784bcc32e754bb89cfc1e96e55 Mon Sep 17 00:00:00 2001
From: Weizhen Wang <wangweizhen@pingcap.com>
Date: Thu, 3 Nov 2022 18:32:01 +0800
Subject: [PATCH] sessionctx: fix tidb_gogc_tuner_threshold  (#38851)

---
 Makefile                      |  2 +-
 sessionctx/variable/sysvar.go | 14 +++++++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 971b5fe1c6..66b3ba0686 100644
--- a/Makefile
+++ b/Makefile
@@ -415,7 +415,7 @@ bazel_coverage_test: failpoint-enable bazel_ci_prepare
 
 bazel_build: bazel_ci_prepare
 	mkdir -p bin
-	bazel $(BAZEL_GLOBAL_CONFIG) build --remote_download_minimal $(BAZEL_CMD_CONFIG) \
+	bazel $(BAZEL_GLOBAL_CONFIG) build $(BAZEL_CMD_CONFIG) \
 		//... --//build:with_nogo_flag=true
 	bazel $(BAZEL_GLOBAL_CONFIG) build $(BAZEL_CMD_CONFIG) \
 		//cmd/importer:importer //tidb-server:tidb-server //tidb-server:tidb-server-check --//build:with_nogo_flag=true
diff --git a/sessionctx/variable/sysvar.go b/sessionctx/variable/sysvar.go
index 9b75a0c685..9ee4fea857 100644
--- a/sessionctx/variable/sysvar.go
+++ b/sessionctx/variable/sysvar.go
@@ -748,12 +748,20 @@ var defaultSysVars = []*SysVar{
 			}
 			return strconv.FormatFloat(floatValue, 'f', -1, 64), nil
 		},
-		SetGlobal: func(_ context.Context, s *SessionVars, val string) error {
+		SetGlobal: func(_ context.Context, s *SessionVars, val string) (err error) {
 			factor := tidbOptFloat64(val, DefTiDBGOGCTunerThreshold)
 			GOGCTunerThreshold.Store(factor)
 			memTotal := memory.ServerMemoryLimit.Load()
-			threshold := float64(memTotal) * factor
-			gctuner.Tuning(uint64(threshold))
+			if memTotal == 0 {
+				memTotal, err = memory.MemTotal()
+				if err != nil {
+					return err
+				}
+			}
+			if factor > 0 {
+				threshold := float64(memTotal) * factor
+				gctuner.Tuning(uint64(threshold))
+			}
 			return nil
 		},
 	},