THE FOLD / GLITCH / RACE CONDITION / THE POISON MESSAGE
THE POISON MESSAGE
busy, at full CPU, making no progress
1 WHAT IT IS · WHAT IT DOES · FACT OR FICTION
A queue with ordered delivery and infinite retry has a failure mode with no moving parts: one message that can never be processed stops every message behind it, forever.
LIT verified live. 1,000 messages, one poison at position 7. With unlimited retry the consumer processes 7 messages, burns 200,000 attempts, and never drains. With a dead-letter queue after 3 attempts it processes 999, spends 1,002 attempts, sets 1 message aside, and finishes. One message held 992 others hostage.
LIT verified live. 1,000 messages, one poison at position 7. With unlimited retry the consumer processes 7 messages, burns 200,000 attempts, and never drains. With a dead-letter queue after 3 attempts it processes 999, spends 1,002 attempts, sets 1 message aside, and finishes. One message held 992 others hostage.
2 HOW IT WAS WEAVED · AI + HUMAN
Dead-letter queues exist for exactly this; the failure is common enough that ordered-delivery systems treat a retry cap as mandatory rather than optional.
AVAN (AI) reports the work column alongside the throughput one, because 200,000 attempts for 7 messages is the part that hurts. The consumer is not idle or crashed — it is fully busy, at maximum CPU, making no progress, which is the hardest failure to spot on a dashboard.
AVAN (AI) reports the work column alongside the throughput one, because 200,000 attempts for 7 messages is the part that hurts. The consumer is not idle or crashed — it is fully busy, at maximum CPU, making no progress, which is the hardest failure to spot on a dashboard.
3 ONE DIMENSION
The queue, with and without a retry cap.
4 TWO DIMENSIONS · INTERACTIVE
Set the retry cap and watch the queue drain or not.
5 THREE DIMENSIONS + AVAN’S INVERSE
The green forward object: a queue stopped at position seven.
AVAN’s addition (the inverse-companion): the forward reading is that a dead-letter queue rescues the consumer. The inverse is that it rescues it by abandoning correctness for one message. The retry cap is a decision that after three tries you will stop trying to do something you were asked to do, and set it aside where nobody is watching. Read backwards, ordered delivery and guaranteed processing cannot both survive a message that will never succeed, and every dead-letter queue is a quiet admission of which one was given up.
LIT 1,000 messages with one poison at position 7: unlimited retry processes 7, burns 200,000 attempts and never drains, while a dead-letter queue after 3 attempts processes 999, spends 1,002 attempts, sets 1 message aside and finishes - one message held 992 others hostage
FIG Dead-letter queues exist for exactly this; the failure is common enough that ordered-delivery systems treat a retry cap as mandatory. AVAN reports the work column alongside the throughput one, because 200,000 attempts for 7 messages is the part that hurts. The consumer is not idle or crashed - it is fully busy, at maximum CPU, making no progress, which is the hardest failure to spot on a dashboard.
FIG Dead-letter queues exist for exactly this; the failure is common enough that ordered-delivery systems treat a retry cap as mandatory. AVAN reports the work column alongside the throughput one, because 200,000 attempts for 7 messages is the part that hurts. The consumer is not idle or crashed - it is fully busy, at maximum CPU, making no progress, which is the hardest failure to spot on a dashboard.
◆ sealed .dlw.fold → folded to ROOT_0 · a sphere of RACE CONDITION · David Lee Wise (ROOT0), with AVAN