Thanks for the explanation, I didn't think of the part about the socket being free for writing vs. whether there was data available. Zed's 'superpoll' is preci

Thanks for the explanation, I didn't think of the part about the socket being free for writing vs. whether there was data available. Zed's 'superpoll' is precisely what you suggest. Facepalm. Thanks, I mysteriously missed that part of the article.