I have to puts large amounts of data to a file in TCL, and it takes very long. I tried increasing the buffer capacity from 4KB to 1MB using fconfigure, but noticed no improvement whatsoever.
I am not sure if I could flush my buffer at intervals, as I was guessing some of my data would be lost if I do so.
Is there some way I could increase the speed of puts without losing any data?
Generally the output speed is going to be limited by your disk drive's speed and computer system's i/o bandwidth.
Increasing the buffer size is probably the only thing you can do to help.
flush will slow down the write, as it will force-push the write buffer to the operating system.
If your incoming data stream ever pauses or comes in one big chunk that can be fit into memory, you can buffer the incoming data internally, and let the write catch up later.