Delay when writing to a file

[zanzibar4]

I have a rather large program that periodically calls a subroutine. Inside the subroutine I write out a variable each time the subroutine is called. If I write it to the screen:

WRITE(*,*) HGT (1)

the correct value appears immediately. However, if I write it to a file

WRITE(4,*) HGT (1), the file remains empty for hundreds of subroutine calls, and then suddenly fills up with hundreds of values.

They are the correct values, but I would rather not wait 5 minutes before I can check whether or not the code is writing out the correct values.

Does anyone have any idea what the issue might be?

 

[xwb]

It is buffered to improve processing. Some compilers support FLUSH as a keyword, others as a subroutine. Something like

CALL FLUSH(channel)

or

FLUSH (UNIT=channel)

You could try that.

 

[xwb]

If you are using the IVF compiler, you could use COMMITQQ. On IVF, FLUSH only works in non-blocking mode so the I/O may not have completed when you call FLUSH.