Panic observed when a building(SQ) index is used for serving the query while there is PQ already serving the same query load.

CREATE INDEX `bigann_100M_PQ` ON `default1`(`color`,`embedding` VECTOR) PARTITION BY hash((meta().`id`)) WITH { "defer_build":true, "nodes":[ "172.23.110.66:18091","172.23.110.67:18091","172.23.110.69:18091" ], "num_partition":8 "dimension":128, "similarity":"L2_SQUARED", "description":"IVF,PQ32x8", "scan_nprobes":20 }

SELECT RAW id FROM {collection} where color in ['green', 'red'] ORDER BY ANN(embedding, $qvec, 'L2_SQUARED', 20) ASC LIMIT 1000

CREATE INDEX `bigann_100M_SQ` ON `default1`(`color`,`embedding` VECTOR) PARTITION BY hash((meta().`id`)) WITH { "defer_build":true, "nodes":[ "172.23.110.66:18091","172.23.110.67:18091","172.23.110.69:18091" ], "num_partition":8 "dimension":128, "similarity":"L2_SQUARED", "description":"IVF,SQ8", "scan_nprobes":20 }

2024-08-20T13:39:56.945-07:00 [Fatal] IndexScanSource2 - panic sync: WaitGroup is reused before previous Wait has returned detected while processing defnId:8993416600612108291, instId:13902447290580810882, index:default1/bigann_100M_SQ, type:vectorscanreq, partitions:[5 8] user:Administrator, span:<ud>(range (nil,nil incl:none))</ud>, limit:9223372036854775807, consistency:any_consistency, requestId:eba5f3a5-9a70-49f5-8720-cd214e4583e8

2024-08-20T13:39:56.983-07:00 [Fatal] goroutine 3349050648 [running]:

github.com/couchbase/indexing/secondary/logging.(*destination).StackTraceAll(...)

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/indexing/secondary/logging/logging.go:179

github.com/couchbase/indexing/secondary/logging.StackTraceAll()

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/indexing/secondary/logging/logging.go:319 +0x3c

github.com/couchbase/indexing/secondary/indexer.(*IndexScanSource2).Routine.func1()

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline_vector.go:790 +0xaa

panic({0x17e3400?, 0x21af360?})

        /home/couchbase/.cbdepscache/exploded/x86_64/go-1.22.5/go/src/runtime/panic.go:770 +0x132

sync.(*WaitGroup).Wait(0xc009f39f80?)

        /home/couchbase/.cbdepscache/exploded/x86_64/go-1.22.5/go/src/sync/waitgroup.go:118 +0x74

github.com/couchbase/indexing/secondary/indexer.(*WorkerPool).Stop.func1()

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline_vector.go:576 +0x36

sync.(*Once).doSlow(0xc00b336ba0?, 0x0?)

        /home/couchbase/.cbdepscache/exploded/x86_64/go-1.22.5/go/src/sync/once.go:74 +0xc2

sync.(*Once).Do(...)

        /home/couchbase/.cbdepscache/exploded/x86_64/go-1.22.5/go/src/sync/once.go:65

github.com/couchbase/indexing/secondary/indexer.(*WorkerPool).Stop(0xc011709440?)

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline_vector.go:574 +0x3c

github.com/couchbase/indexing/secondary/indexer.(*IndexScanSource2).Routine(0xc00e906070)

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline_vector.go:924 +0xa05

github.com/couchbase/indexing/secondary/pipeline.(*Pipeline).runIt.func1()

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/indexing/secondary/pipeline/pipeline.go:75 +0x32

created by github.com/couchbase/indexing/secondary/pipeline.(*Pipeline).runIt in goroutine 1065688906

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/indexing/secondary/pipeline/pipeline.go:74 +0x79