How to (can I) ask a PIPE how many bytes it has available for reading?
Clash Royale CLAN TAG #URR8PPP How to (can I) ask a PIPE how many bytes it has available for reading? I've implemented a non-blocking reader in Python, and I need to make it more efficient. The background: I have massive amounts of output that I need to read from one subprocess (started with Popen()) and pass to another thread. Reading the output from that subprocess must not block for more than a few ms (preferably for as little time as is necessary to read available bytes). Currently, I have a utility class which takes a file descriptor (stdout) and a timeout. I select() and readline(1) until one of three things happens: select() readline(1) Then I return the buffered text to the calling method, which does stuff with it. Now, for the real question: because I'm reading so much output, I need to make this more efficient. I'd like to do that by asking the file descriptor how many bytes are pending and then readline([that many bytes]) . It's supposed to just pass stuff ...