This is an automated cherry-pick of pingcap#58328

Signed-off-by: ti-chi-bot <[email protected]>

Author: qw4990

pkg/expression/constant.go

@@ -167,20 +167,21 @@ func (d *ParamMarker) GetUserVar(ctx ParamValues) (types.Datum, error) {
 
 // StringWithCtx implements Expression interface.
 func (c *Constant) StringWithCtx(ctx ParamValues, redact string) string {
+	v := c.Value
 	if c.ParamMarker != nil {
 		dt, err := c.ParamMarker.GetUserVar(ctx)
 		intest.AssertNoError(err, "fail to get param")
 		if err != nil {
 			return "?"
 		}
-		c.Value.SetValue(dt.GetValue(), c.RetType)
+		v = dt
 	} else if c.DeferredExpr != nil {
 		return c.DeferredExpr.StringWithCtx(ctx, redact)
 	}
 	if redact == perrors.RedactLogDisable {
-		return c.Value.TruncatedStringify()
+		return v.TruncatedStringify()
 	} else if redact == perrors.RedactLogMarker {
-		return fmt.Sprintf("‹%s›", c.Value.TruncatedStringify())
+		return fmt.Sprintf("‹%s›", v.TruncatedStringify())
 	}
 	return "?"
 }
@@ -312,8 +313,7 @@ func (c *Constant) Eval(ctx EvalContext, row chunk.Row) (types.Datum, error) {
 			return c.Value, err
 		}
 		if dt.IsNull() {
-			c.Value.SetNull()
-			return c.Value, nil
+			return dt, nil
 		}
 		if c.DeferredExpr != nil {
 			if dt.Kind() != types.KindMysqlDecimal {

pkg/planner/core/casetest/instanceplancache/BUILD.bazel

@@ -2,7 +2,7 @@ load("@io_bazel_rules_go//go:def.bzl", "go_test")
 
 go_test(
     name = "instanceplancache_test",
-    timeout = "short",
+    timeout = "moderate",
     srcs = [
         "concurrency_test.go",
         "concurrency_tpcc_test.go",
@@ -11,7 +11,12 @@ go_test(
         "others_test.go",
     ],
     flaky = True,
+<<<<<<< HEAD
     shard_count = 18,
+=======
+    race = "on",
+    shard_count = 40,
+>>>>>>> 80b34784bf5 (planner: fix possible read-write DATA RACE on Instance Plan Cache (#58328))
     deps = [
         "//pkg/parser/auth",
         "//pkg/testkit",

pkg/planner/core/plan_cache.go

@@ -321,7 +321,15 @@ func generateNewPlan(ctx context.Context, sctx sessionctx.Context, isNonPrepared
 		stmtCtx.SetPlan(p)
 		stmtCtx.SetPlanDigest(stmt.NormalizedPlan, stmt.PlanDigest)
 		if instancePlanCacheEnabled(ctx) {
-			domain.GetDomain(sctx).GetInstancePlanCache().Put(cacheKey, cached, paramTypes)
+			if cloned, ok := p.CloneForPlanCache(sctx.GetPlanCtx()); ok {
+				// Clone this plan before putting it into the cache to avoid read-write DATA RACE. For example,
+				// before this session finishes the execution, the next session has started cloning this plan.
+				// Time:  | ------------------------------------------------------------------------------- |
+				// Sess1: | put plan into cache | ----------- execution (might modify the plan) ----------- |
+				// Sess2:                  | start | ------- hit this plan and clone it (DATA RACE) ------- |
+				cached.Plan = cloned
+				domain.GetDomain(sctx).GetInstancePlanCache().Put(cacheKey, cached, paramTypes)
+			}
 		} else {
 			sctx.GetSessionPlanCache().Put(cacheKey, cached, paramTypes)
 		}