调用 ReadFile 返回 ERROR_WORKING_SET_QUOTA答案

【问题标题】：Calls to ReadFile return ERROR_WORKING_SET_QUOTA调用 ReadFile 返回 ERROR_WORKING_SET_QUOTA
【发布时间】：2010-08-09 17:06:40
【问题描述】：

程序正常运行了几分钟，然后 ReadFile 开始失败，错误代码为 ERROR_WORKING_SET_QUOTA。

我正在使用带有重叠 I/O 的 ReadFile，如下所示：

while (continueReading)
{
    BOOL bSuccess = ReadFile(deviceHandle, pReadBuf, length, 
                             &bytesRead, readOverlappedPtr);
    waitVal = WaitForMultipleObjects(
                (sizeof(eventsToWaitFor)/sizeof(eventsToWaitFor[0])), 
                eventsToWaitFor, FALSE, INFINITE);
    if (waitVal == WAIT_OBJECT_0) {
       // do stuff
    } else if (waitVal == WAIT_OBJECT_0 + 1) {
       // do stuff
    } else if (waitVal == WAIT_OBJECT_0 + 2) {
       // complete the read
       bSuccess = GetOverlappedResult(deviceHandle, &readOverlapped, 
                                      &bytesRead, FALSE);
       if (!bSuccess) {
          errorCode = GetLastError();
          printf("ReadFile error=%d\n", errorCode);
       }
    }
}

为什么会出现这个错误？

【问题讨论】：

标签： winapi readfile overlapped-io

【解决方案1】：

问题是ReadFile 被调用的次数比GetOverlappedResult 多。导致进程耗尽资源来处理所有未完成的读取。

另外，我们应该检查ReadFile的结果，并确保结果是ERROR_IO_PENDING，如果不是并且ReadFile返回FALSE，那么还有另一个问题。

确保每次成功调用ReadFile 都会调用一次GetOverlappedResult。像这样：

BOOL bPerformRead = TRUE;
while (continueReading) 
{ 
    BOOL bSuccess = TRUE;
    // only perform the read if the last one has finished
    if (bPerformRead) {
       bSuccess = ReadFile(deviceHandle, pReadBuf, length,
                           &bytesRead, readOverlappedPtr);
       if (!bSuccess) {
          errorCode = GetLastError();
          if (errorCode != ERROR_IO_PENDING) {
             printf("ReadFile error=%d\n", errorCode); 
             return;
          }
       } else {
          // read completed right away
          continue;
       }
       // we can't perform another read until this one finishes
       bPerformRead = FALSE;
    }
    waitVal = WaitForMultipleObjects( 
                (sizeof(eventsToWaitFor)/sizeof(eventsToWaitFor[0])),  
                eventsToWaitFor, FALSE, INFINITE); 
    if (waitVal == WAIT_OBJECT_0) { 
       // do stuff 
    } else if (waitVal == WAIT_OBJECT_0 + 1) { 
       // do stuff 
    } else if (waitVal == WAIT_OBJECT_0 + 2) { 
       // complete the read 
       bSuccess = GetOverlappedResult(deviceHandle, &readOverlapped,  
                                      &bytesRead, FALSE); 
       // the read is finished, we can read again
       bPerformRead = TRUE;
       if (!bSuccess) { 
          errorCode = GetLastError(); 
          printf("GetOverlappedResult from ReadFile error=%d\n", errorCode); 
       } 
    } 
}

【讨论】：

更接近。但实际上验证 ReadFile 返回 FALSE 和 GetLastError() 返回 ERROR_IO_PENDING 是非常重要的。当数据从文件系统缓存中出来时，读取文件通常会立即完成。