HDF5 File Locking Mechanism

HDF5 Library C++ Users' Group
1

Hi all,
I’ve been experimenting with the HDF5 file locking mechanism and encountered some unexpected behavior (hdf5 1.14.4). Below is the code snippet I used to test the file locking:

#include "hdf5.h"
#include "H5Cpp.h"

#include <cstdio>
#include <iostream>
   // Create file access property list with file locking disabled
   bool isLockedFile = false; // Seems to work upside down
   H5::FileAccPropList accessPropList;
   accessPropList.setFileLocking(isLockedFile, true);

   // Create an HDF5 file with the specified access properties
   H5::H5File file = H5::H5File("testopen.h5", H5F_ACC_TRUNC, H5::FileCreatPropList::DEFAULT, accessPropList);

   //Check locking property
   // Check the locking property of the created file
   const H5::FileAccPropList pList(file.getAccessPlist());
   hbool_t isLocked = true;
   hbool_t isIgnored = true;
   pList.getFileLocking(isLocked, isIgnored);
   std::cout << "isLocked: " << (isLocked ? "true" : "false") << std::endl;

   // Attempt to open the same file again
   H5::H5File file2;
   try
   {
       file2.openFile("testopen.h5", H5F_ACC_RDONLY);
       std::cout << "File opened successfully." << std::endl;
   }
   catch (const H5::FileIException& e)
   {
       std::cerr << "Failed to open file: " << e.getCDetailMsg() << std::endl;
   }

   // Close the files
   file2.close();
   file.close();

• When isLockedFile is set to false, the file locking mechanism is supposed to be disabled. However, the code successfully opens the file twice, which is unexpected.
• When isLockedFile is set to true, the file locking mechanism is supposed to be enabled. Surprisingly, the code fails to open the file a second time, which contradicts the expected behavior.

Has anyone else encountered this behavior? Is there something I’m missing in the configuration or usage of the HDF5 file locking mechanism?

2

Hi Jonathan, please take a look at

and check your environment variable setting. That might explain the unexpected behaviors.