Data not written to filesink in gnuradio

Question

Here is my simple flow graph.

File Source > Throttle > File Sink

It works fine when the repeat value of File Source is on. When i turn off the repeat value of File Source, nothing gets written. what could be the reason for this?

Answer 1

Buffering of the GNU Radio scheduler between the blocks may be the cause of your problem. Especially, if the sampling rate of the throttle is slow. Furthermore, the file sink block uses the fwrite() function that also performs some buffering to increase the throughput. You can inform the file sink block to flush immediately the fwrite() buffer, setting the Unbuffered parameter to On from the gnuradio-companion GUI.