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I suspect I have encountered an unfixed bug brought about by the introduction of buffer chests... it has to do with the "request from buffer chests" check-box. Check out the attached save (mod hacks should be down to just the one hacked up blueprint flipper mod which I've attached; remaining mods are standard from-the-portal mods which the automagic "sync mods with save" feature should cover fine).

In the save you'll see I'm standing next to a terrible hack which builds green science from robot logistics. Note, in particular, the requestor feeding the iron-gear-wheel assembler just to my right. If you open up the UI for that requester chest, and hover the mouse over the request slot for iron plates, you'll see that

• There is a general shortage of iron plates in my network
• The checkbox for "request from buffer chests" is checked

Note that no items are scheduled for delivery and that, even if you wait for a very long time, no iron plates are ever delivered to this chest. Yet, there are requesters nearby getting delivery just fine. Now, returning to the requester chest UI, go in and turn off "request from buffer chests", and hover the mouse over the iron-plates request slot again. You will see that immediately items are scheduled for delivery. I would bet just about anything that if you cheat in a provider chest with a million iron plates in it, all of a sudden, iron plates would start being delivered as well -- in my experience if I change either bullet point above, deliveries resume.

What I believe is happening is that somehow requester chests with "request from buffer chests" checked are effectively given a lower fulfillment priority when scheduling logistics deliveries of scarce items in busy networks, either because they are in a different queue which starves for deliveries in a shortage, or, if there is just one queue/list, then due to some glitch in the code which normally slides the fulfillment window in a loop over the list of requesters (which would normally ensure that in, a shortage, everybody gets a little bit), causing starvation of some (but maybe not all) requesters configured to request from buffer chests. It might be a build-order thing; these chests are among the last to have been built in this network.

[Moderatrivia: the above is a word-for-word repost of a (misplaced, sorry for that!) previous bug report that I believe Kovarex dismissed in error (which in turn led me to falsely believe my report might be based on a faulty assumption, but I no longer think so... Sorry, for such confusion ... it's like a really boring episode of "Three's Company"). Anyhow I'm pretty sure he interpreted the above as "I have this buffer chest and it's starving" but it actually says: "I have this requester chest and it's starving". If I'm just being thick (quite possible) I'd at least like to figure out where I lost the plot.]

Kovarex did following change for 0.16.21

- Requesters requesting from buffer chests (which includes player) have higher priority than other requesters.

So, let us know if it is still problem when 0.16.21 is released.

posila wrote:Kovarex did following change for 0.16.21

- Requesters requesting from buffer chests (which includes player) have higher priority than other requesters.

So, let us know if it is still problem when 0.16.21 is released.

Well spotted. I loaded up my save above in 0.16.22 and, sho 'nuff, the requestor immediately starts getting plates.