When Should You Explicitly Sync a File in Go?

When Should You Explicitly Flush a File in Go?

Although you may assume that closing a file will automatically flush its contents to disk, this is not always the case. In Go, os.File does not have a dedicated .Flush() method because it's not buffered and writes are handled by direct syscalls.

However, when the operating system shuts down or your program terminates (even abruptly), all open files are closed automatically. However, the file system may not immediately write the modified contents to disk. This means there could be a delay before your changes become persistent.

To ensure immediate flushing of file contents, you should manually call os.File.Sync(). This function invokes the fsync() syscall, forcing the file system to write its buffers to disk. As a result, your data will be safely written and preserved even if your system malfunctions or the power supply is interrupted.

While closing a file typically suffices for general scenarios, using Sync() can provide additional assurance that your changes are immediately reflected on the disk, enhancing data integrity and reliability.

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