Poll usage: Hangup on pending write and Buffer Limits

Currently our way to invoke poll is pretty hacky and it might cause us problems in two situations:

If we write to the buffer limit we might have to read first to get more. I don't see how that is in general possible with redis as redis cannot start processing unless it got the entire pipeline, but i need to verify that this is not an issue with writing to different redises
I think we might not support a hangup while writing. Need to verify this.

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