@alexander-schranz can you please confirm that this change makes sense to you? It adds explicitBLOCK 1 to the xreadgroup command. (ext-redis 5 & 6 don't have the same default for this argument apparently, I'm trying to figure out how we should write the code to deal with both versions.)

This looks like the new default, what was the previous one? I try to understand / find the change inside the phpredis extension, did you already find that?

The C code looks a but blurry to me. It looks like the behavior depends on the number of arguments, not on the actual values :'(
Is there a value of BLOCK that works for the need here? eg this1?

In generally I don't see a problem of a Block for 1ms to wait for any messages. The PHP Extension part for me between 5.3.7 and 6.0.1 did look the same so maybe its inside Redis itself? Or was just the redis extension updated? Another possibility would be that we check for the version viaphpversion('redis'); but that just returns the extension version not the server version. I try to find out when the added noblock feature as I maybe think its related to that changes 🤔 .

Let me merge this to make tests green but please let me know if you discover1 isn't what we need.