copr: add ballast mem to reduce the runtime overhead during execution (#53407) (#53429)

ref #52887

Author: ti-chi-bot

pkg/store/copr/BUILD.bazel

@@ -35,6 +35,7 @@ go_library(
         "//pkg/util/logutil",
         "//pkg/util/memory",
         "//pkg/util/paging",
+        "//pkg/util/size",
         "//pkg/util/tiflash",
         "//pkg/util/tiflashcompute",
         "//pkg/util/tracing",

pkg/store/copr/coprocessor.go

@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"math"
 	"net"
+	"runtime"
 	"strconv"
 	"strings"
 	"sync"
@@ -50,6 +51,7 @@ import (
 	"github.com/pingcap/tidb/pkg/util/logutil"
 	"github.com/pingcap/tidb/pkg/util/memory"
 	"github.com/pingcap/tidb/pkg/util/paging"
+	"github.com/pingcap/tidb/pkg/util/size"
 	"github.com/pingcap/tidb/pkg/util/tracing"
 	"github.com/pingcap/tidb/pkg/util/trxevents"
 	"github.com/pingcap/tipb/go-tipb"
@@ -822,6 +824,10 @@ func (worker *copIteratorWorker) run(ctx context.Context) {
 		})
 		worker.wg.Done()
 	}()
+	// 16KB ballast helps grow the stack to the requirement of copIteratorWorker.
+	// This reduces the `morestack` call during the execution of `handleTask`, thus improvement the efficiency of TiDB.
+	// TODO: remove ballast after global pool is applied.
+	ballast := make([]byte, 16*size.KB)
 	for task := range worker.taskCh {
 		respCh := worker.respChan
 		if respCh == nil {
@@ -840,6 +846,7 @@ func (worker *copIteratorWorker) run(ctx context.Context) {
 			return
 		}
 	}
+	runtime.KeepAlive(ballast)
 }
 
 // open starts workers and sender goroutines.