RoutingGrain back-pressure episodes on portal pod: dispatch pool saturated by ThreadPool wait during burst, threshold 64 crossed repeatedly #5416

2026-09-22 22:53:23Z memex-portal-deployment-857546649-vf2q6 crit: MeshWeaver.Hosting.Orleans.RoutingGrain[0]
      [ROUTE] Routing back-pressure [9bff309f#3 started 2026-09-22T22:53:23.6484815Z]: 64 route dispatches in flight (reporting threshold 64); ordered channels queued 61 over 5 stream destination(s), deepest per-channel queue 0, routing pool subscribing 0, waiting for a pool slot 17; oldest leg in flight 185 ms — stream-routed → cache/41czPxYhBke8Yz-MPeDDVQ (delivery FGBzGOvTrEuMfosfluAX6w). Latest dispatch target Admin/_PluginGrant/memex — the address that happened to cross the threshold, NOT a diagnosis. A slot is held from dispatch until the leg terminates, INCLUDING the unbounded wait for a ThreadPool thread before the leg's own timeouts start, so a CPU-starved silo raises this with nothing stuck. A CHANNEL is (destination, stream), so a deepest queue of 1 or more means legs of the SAME stream are blocked behind one another (head-of-line within one channel); 0 means nothing is waiting on anything, so read it as load. Many channels over FEW destinations is a multiplexer hub draining in parallel, which is load too — before issue #5009 those legs shared one channel and read as head-of-line. 🚨 THE TWO POOL GAUGES ANSWER DIFFERENT QUESTIONS AND ONLY ONE SEES THE WAIT NAMED ABOVE — issue #5018. 'subscribing' counts legs inside their SUBSCRIBE PROLOGUE only, so a leg still waiting for a ThreadPool thread and a leg already past its subscribe BOTH read 0 there; 'waiting for a pool slot' is the gauge that sees the pre-subscribe wait. High while subscribing is below the pool's cap is a THREAD shortage; both near zero means the legs are past their subscribe and the wait is downstream I/O. 🚨 READ THE OLDEST LEG FIRST: it is the only load-vs-leak discriminator available from a SINGLE line — every leg young is load the silo is absorbing, one leg minutes old is a slot that never came back and the label names it — whereas the episode stamp below needs a SECOND line to say anything. 🚨 Deepest is sampled AT THE CROSSING, so like …[truncated]
2026-09-22 22:53:51Z memex-portal-deployment-857546649-vf2q6 crit: MeshWeaver.Hosting.Orleans.RoutingGrain[0]
      [ROUTE] Routing back-pressure [49e69485#1 started 2026-09-22T22:53:51.3441960Z]: 64 route dispatches in flight (reporting threshold 64); ordered channels queued 0 over 0 stream destination(s), deepest per-channel queue 0, routing pool subscribing 0, waiting for a pool slot 58; oldest leg in flight 46 ms — dispatch → Manufacturing/WorkOrder/_Activity/compile-state (delivery yBHtHXBgrECgVryPR632UQ). Latest dispatch target Hosting/TriageStatus — the address that happened to cross the threshold, NOT a diagnosis. A slot is held from dispatch until the leg terminates, INCLUDING the unbounded wait for a ThreadPool thread before the leg's own timeouts start, so a CPU-starved silo raises this with nothing stuck. A CHANNEL is (destination, stream), so a deepest queue of 1 or more means legs of the SAME stream are blocked behind one another (head-of-line within one channel); 0 means nothing is waiting on anything, so read it as load. Many channels over FEW destinations is a multiplexer hub draining in parallel, which is load too — before issue #5009 those legs shared one channel and read as head-of-line. 🚨 THE TWO POOL GAUGES ANSWER DIFFERENT QUESTIONS AND ONLY ONE SEES THE WAIT NAMED ABOVE — issue #5018. 'subscribing' counts legs inside their SUBSCRIBE PROLOGUE only, so a leg still waiting for a ThreadPool thread and a leg already past its subscribe BOTH read 0 there; 'waiting for a pool slot' is the gauge that sees the pre-subscribe wait. High while subscribing is below the pool's cap is a THREAD shortage; both near zero means the legs are past their subscribe and the wait is downstream I/O. 🚨 READ THE OLDEST LEG FIRST: it is the only load-vs-leak discriminator available from a SINGLE line — every leg young is load the silo is absorbing, one leg minutes old is a slot that never came back and the label names it — whereas the episode stamp below needs a SECOND line to say anything. 🚨 Deepest is sampled AT THE CROSSING, …[truncated]
2026-09-22 22:53:51Z memex-portal-deployment-857546649-vf2q6 crit: MeshWeaver.Hosting.Orleans.RoutingGrain[0]
      [ROUTE] Routing back-pressure [49e69485#2 started 2026-09-22T22:53:51.6661150Z]: 64 route dispatches in flight (reporting threshold 64); ordered channels queued 0 over 0 stream destination(s), deepest per-channel queue 0, routing pool subscribing 0, waiting for a pool slot 47; oldest leg in flight 109 ms — dispatch → ReinsuranceDemo/Installer (delivery iC158yOvGU20qJHn4WOu4A). Latest dispatch target EventMonitoring/PerilEvent — the address that happened to cross the threshold, NOT a diagnosis. A slot is held from dispatch until the leg terminates, INCLUDING the unbounded wait for a ThreadPool thread before the leg's own timeouts start, so a CPU-starved silo raises this with nothing stuck. A CHANNEL is (destination, stream), so a deepest queue of 1 or more means legs of the SAME stream are blocked behind one another (head-of-line within one channel); 0 means nothing is waiting on anything, so read it as load. Many channels over FEW destinations is a multiplexer hub draining in parallel, which is load too — before issue #5009 those legs shared one channel and read as head-of-line. 🚨 THE TWO POOL GAUGES ANSWER DIFFERENT QUESTIONS AND ONLY ONE SEES THE WAIT NAMED ABOVE — issue #5018. 'subscribing' counts legs inside their SUBSCRIBE PROLOGUE only, so a leg still waiting for a ThreadPool thread and a leg already past its subscribe BOTH read 0 there; 'waiting for a pool slot' is the gauge that sees the pre-subscribe wait. High while subscribing is below the pool's cap is a THREAD shortage; both near zero means the legs are past their subscribe and the wait is downstream I/O. 🚨 READ THE OLDEST LEG FIRST: it is the only load-vs-leak discriminator available from a SINGLE line — every leg young is load the silo is absorbing, one leg minutes old is a slot that never came back and the label names it — whereas the episode stamp below needs a SECOND line to say anything. 🚨 Deepest is sampled AT THE CROSSING, so like the in-…[truncated]
2026-09-22 22:53:52Z memex-portal-deployment-857546649-vf2q6 crit: MeshWeaver.Hosting.Orleans.RoutingGrain[0]
      [ROUTE] Routing back-pressure [49e69485#3 started 2026-09-22T22:53:52.2124225Z]: 64 route dispatches in flight (reporting threshold 64); ordered channels queued 0 over 0 stream destination(s), deepest per-channel queue 0, routing pool subscribing 0, waiting for a pool slot 60; oldest leg in flight 21 ms — dispatch → Claims/Enquiry/_Activity/compile-state (delivery Ctiym1GC_EWpDVA9HQI6Xg). Latest dispatch target Ifrs17/RiskDriver — the address that happened to cross the threshold, NOT a diagnosis. A slot is held from dispatch until the leg terminates, INCLUDING the unbounded wait for a ThreadPool thread before the leg's own timeouts start, so a CPU-starved silo raises this with nothing stuck. A CHANNEL is (destination, stream), so a deepest queue of 1 or more means legs of the SAME stream are blocked behind one another (head-of-line within one channel); 0 means nothing is waiting on anything, so read it as load. Many channels over FEW destinations is a multiplexer hub draining in parallel, which is load too — before issue #5009 those legs shared one channel and read as head-of-line. 🚨 THE TWO POOL GAUGES ANSWER DIFFERENT QUESTIONS AND ONLY ONE SEES THE WAIT NAMED ABOVE — issue #5018. 'subscribing' counts legs inside their SUBSCRIBE PROLOGUE only, so a leg still waiting for a ThreadPool thread and a leg already past its subscribe BOTH read 0 there; 'waiting for a pool slot' is the gauge that sees the pre-subscribe wait. High while subscribing is below the pool's cap is a THREAD shortage; both near zero means the legs are past their subscribe and the wait is downstream I/O. 🚨 READ THE OLDEST LEG FIRST: it is the only load-vs-leak discriminator available from a SINGLE line — every leg young is load the silo is absorbing, one leg minutes old is a slot that never came back and the label names it — whereas the episode stamp below needs a SECOND line to say anything. 🚨 Deepest is sampled AT THE CROSSING, so like the …[truncated]