From 46d5b31fc906f2ee863cda172e783e49cd46fc99 Mon Sep 17 00:00:00 2001
From: Morgan Tocker <tocker@gmail.com>
Date: Thu, 13 May 2021 09:05:10 -0600
Subject: [PATCH] Make reading getsysvar list concurrency safe

---
 sessionctx/variable/sysvar.go | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/sessionctx/variable/sysvar.go b/sessionctx/variable/sysvar.go
index bcd5e3b719485..6121ad61552ac 100644
--- a/sessionctx/variable/sysvar.go
+++ b/sessionctx/variable/sysvar.go
@@ -509,11 +509,15 @@ func SetSysVar(name string, value string) {
 	sysVars[name].Value = value
 }
 
-// GetSysVars returns the sysVars list under a RWLock
+// GetSysVars deep copies the sysVars list under a RWLock
 func GetSysVars() map[string]*SysVar {
 	sysVarsLock.RLock()
 	defer sysVarsLock.RUnlock()
-	return sysVars
+	copy := make(map[string]*SysVar, len(sysVars))
+	for name, sv := range sysVars {
+		copy[name] = sv
+	}
+	return copy
 }
 
 // PluginVarNames is global plugin var names set.