executor: fix data race. (#3284)
executor: fix data race. (#3284)


louishust/tidb,louishust/tidb,kyle-wang/tidb,yuanwhy/tidb,XuHuaiyu/tidb,8cbx/tidb,ngaut/tidb,c4pt0r/tidb,cosmtrek/tidb,mccxj/tidb,tiancaiamao/tidb,gaocegege/tidb,cosmtrek/tidb,tiancaiamao/tidb,spongedu/tidb,silentred/tidb,ming-relax/tidb,kyle-wang/tidb,CodeRushing/tidb,silentred/tidb,ngaut/tidb,ngaut/tidb,gaocegege/tidb,Nify/tidb,ueizhou/tidb,pingcap/tidb,zimulala/tidb,spongedu/tidb,kyle-wang/tidb,Nify/tidb,ueizhou/tidb,kyle-wang/tidb,yangwenmai/tidb,pingcap/tidb,c4pt0r/tidb,c4pt0r/tidb,coocood/tidb,kyle-wang/tidb,pingcap/tidb,kyle-wang/tidb,mccxj/tidb,pingcap/tidb,c4pt0r/tidb,EvilMcJerkface/tidb,qiuyesuifeng/tidb,coocood/tidb,c4pt0r/tidb,ngaut/tidb,qiuyesuifeng/tidb,8cbx/tidb,ngaut/tidb,Cofyc/tidb,c4pt0r/tidb,wusphinx/tidb,CodeRushing/tidb,yangwenmai/tidb,zs634134578/tidb,EvilMcJerkface/tidb,pingcap/tidb,yuanwhy/tidb,wusphinx/tidb,zs634134578/tidb,zimulala/tidb,ming-relax/tidb,ngaut/tidb,Cofyc/tidb,XuHuaiyu/tidb,pingcap/tidb