問題描述

一個歷史表中有大量的數據，現在要通過分頁式查詢處理轉換數據。

現在將處理數據的邏輯放在線程池中處理，以加快處理流程。

可是總是出現事務方面的異常

比如 ： SQLNonTransientConnectionException

請問該如何解決上述異常，或者有什么好的多線程分頁查詢處理方案？

原來問題描述不太清楚，現在添加以下代碼（手敲，如果有錯，請多包含）

分頁式查詢邏輯:

int pageSize = 100;int currentPageLength = 0;int pageIndex = 0;ExecutorService exe = newFixedThreadPool(Runtime.getRuntime().availableProcessors());do { int offset = pageIndex * pageSize; List<TradeInfo> tradeInfos = tradeInfoService.findTradeInfoBysPage(queryParams,offset,pageSize); if (null != tradeInfos && tradeInfos.size() > 0) {currentPageLength = tradeInfos.size();TradeInfoProcesserTask task = new TradeInfoProcesserTask(tradeInfos );exe.execute(task);pageIndex++; }else{System.out.println('Page Query TradeInfo Got NOTHING! Break query loop!');break; }} while (currentPageLength == pageSize);exe.shutdown();while(true) { if(exe.isTerminated()){doOtherThings();System.out.println('分頁式多線程處理數據完畢！');break; }}

數據處理邏輯:

public class TradeInfoProcesserTask implements Runnable{ private volatile List<TradeInfo> tradeInfos;public TradeInfoProcesserTask (List<TradeInfo> _tradeInfos){tradeInfos = _tradeInfos; }@Override public void run() {processTradeInfos(); }private void processTradeInfos(){//do something with tradeInfos ..... }}

問題解答

邏輯先不說。現在沒有判斷多線程是否全部執行完，while循環完就shutdown。。。將CountDownLatch通過構造器傳入線程

ExecutorService exe = newFixedThreadPool(Runtime.getRuntime().availableProcessors());CountDownLatch latch = new CountDownLatch(?); //?代表開啟全部線程的數量do { int offset = pageIndex * pageSize; List<TradeInfo> tradeInfos = tradeInfoService.findTradeInfoBysPage(queryParams,offset,pageSize); if (null != tradeInfos && tradeInfos.size() > 0) {currentPageLength = tradeInfos.size();TradeInfoProcesserTask task = new TradeInfoProcesserTask(tradeInfos, latch);exe.execute(task);pageIndex++; }else{System.out.println('Page Query TradeInfo Got NOTHING! Break query loop!');break; }} while (currentPageLength == pageSize);latch.await(); //多線程全部執行完exe.shutdown();doOtherThings();System.out.println('分頁式多線程處理數據完畢！');

public class TradeInfoProcesserTask implements Runnable{ private volatile List<TradeInfo> tradeInfos; private CountDownLatch latch;public TradeInfoProcesserTask (List<TradeInfo> _tradeInfos, CountDownLatch latch){tradeInfos = _tradeInfos;this.latch = latch; }@Override public void run() {processTradeInfos();latch.countDown(); }private void processTradeInfos(){//do something with tradeInfos ..... }}回答2：

分頁查詢是不并發（DAO）的，數據處理是并發（Service），所以你的事務級級別是設置在哪個環節呢？