executor: make channel buffer small in sort executor (#53881)

close #53866

pkg/executor/sortexec/sort.go

@@ -169,7 +169,7 @@ func (e *SortExec) Open(ctx context.Context) error {
 		e.Parallel.chunkChannel = make(chan *chunkWithMemoryUsage, e.Ctx().GetSessionVars().ExecutorConcurrency)
 		e.Parallel.fetcherAndWorkerSyncer = &sync.WaitGroup{}
 		e.Parallel.sortedRowsIters = make([]*chunk.Iterator4Slice, len(e.Parallel.workers))
-		e.Parallel.resultChannel = make(chan rowWithError, e.MaxChunkSize())
+		e.Parallel.resultChannel = make(chan rowWithError, 10)
 		e.Parallel.closeSync = make(chan struct{})
 		e.Parallel.merger = newMultiWayMerger(&memorySource{sortedRowsIters: e.Parallel.sortedRowsIters}, e.lessRow)
 		e.Parallel.spillHelper = newParallelSortSpillHelper(e, exec.RetTypes(e), e.finishCh, e.lessRow, e.Parallel.resultChannel)