forkjoinpool 弊端_oracle数据库分页查询sql

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使用forkjoin框架分页查询所有数据的例子

import io.swagger.annotations.ApiOperation;
import lombok.AllArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.PropertySource;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;
@RestController
@RequestMapping("/test2")
@PropertySource("classpath:/application.properties")
@Slf4j
public class ForkJoinPollController { 

@Autowired
private SyncPersonInfoServiceImp syncPersonInfoService;
@ApiOperation("测试forkJoinPoll")
@GetMapping("/forkJoinPoll")
public void forkJoinPoll(){ 

log.info("forkJoinPoll start...");
ForkJoinPool pool = new ForkJoinPool(Runtime.getRuntime().availableProcessors() * 2);
// 总页数,提前查询出来，数据量不大就不用拆任务
int total = syncPersonInfoService.getTotal();
int totalPage = (int)Math.ceil(total * 1.0 / IrdsConstant.PAGE_SIZE_MAX);
SumTask innerFind = new SumTask(1, totalPage);
pool.invoke(innerFind);
List<VChrHkws> join = innerFind.join();
pool.shutdown();
log.info("forkJoinPoll end,size={}",join.size());
}
@AllArgsConstructor
public class SumTask extends RecursiveTask<List<VChrHkws>> { 

private final Integer fromIndex;
private final Integer toIndex;
@Override
protected List<VChrHkws> compute() { 

// 如果任务足够小就触发任务
if (toIndex - fromIndex < 2) { 

List<VChrHkws> list = new ArrayList<>();
for (int pageNo = fromIndex; pageNo <= toIndex; pageNo++) { 

ApiPageListData<VChrHkws> pageData = syncPersonInfoService.getPageListData(pageNo, IrdsConstant.PAGE_SIZE_MAX);
// 查询数据库返回值
list.addAll(pageData.getList());
}
return list;
} else { 

// 如果任务大于阈值，就分裂成两个子任务计算
int mid = (fromIndex + toIndex) / 2;
SumTask left = new SumTask(fromIndex, mid);
SumTask right = new SumTask(mid + 1, toIndex);
invokeAll(left, right);
List<VChrHkws> join = left.join();
join.addAll(right.join());
return join;
}
}
}
}