promql.Engine calls At() after Next() returns false

[tomwilkie]

This is whilst testing #2850:

INFO[0999] mergeIterator.Next                            source="fanout.go:378"
INFO[0999] mergeIterator.Next true                       source="fanout.go:385"
INFO[0999] mergeIterator.Seek t=1499952745180            source="fanout.go:361"
INFO[0999] mergeIterator.Seek true                       source="fanout.go:368"
INFO[0999] mergeIterator.Next                            source="fanout.go:378"
INFO[0999] mergeIterator.Next true                       source="fanout.go:399"
INFO[0999] mergeIterator.Next                            source="fanout.go:378"
INFO[0999] mergeIterator.Next true                       source="fanout.go:399"
INFO[0999] mergeIterator.Next                            source="fanout.go:378"
INFO[0999] mergeIterator.Next true                       source="fanout.go:399"
INFO[0999] mergeIterator.Next                            source="fanout.go:378"
INFO[0999] mergeIterator.Next false                      source="fanout.go:399"
ERRO[0999] parser panic: runtime error: index out of range
goroutine 9853 [running]:
github.com/prometheus/prometheus/promql.(*evaluator).recover(0xc421daad00, 0xc421ded120)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/promql/engine.go:587 +0xd5
panic(0x25b2480, 0x353b0a0)
	/usr/local/Cellar/go/1.8.3/libexec/src/runtime/panic.go:489 +0x2cf
github.com/prometheus/prometheus/storage.(*mergeIterator).At(0xc421db0e70, 0x0, 0x0)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/storage/fanout.go:374 +0x65
github.com/prometheus/prometheus/storage.(*BufferedSeriesIterator).Values(0xc421db0ea0, 0x0, 0x0)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/storage/buffer.go:101 +0x33
github.com/prometheus/prometheus/promql.(*evaluator).matrixSelector(0xc421daad00, 0xc4205779d0, 0x284c0e6, 0x15, 0x0)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/promql/engine.go:854 +0x393
github.com/prometheus/prometheus/promql.(*evaluator).eval(0xc421daad00, 0x348b3c0, 0xc4205779d0, 0xc421ded120, 0xc421daad00)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/promql/engine.go:715 +0x5cb
github.com/prometheus/prometheus/promql.(*evaluator).Eval(0xc421daad00, 0x348b3c0, 0xc4205779d0, 0x0, 0x0, 0x0, 0x0)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/promql/engine.go:666 +0xd3
github.com/prometheus/prometheus/promql.(*Engine).execEvalStmt(0xc420776b70, 0x5102298, 0xc421da9260, 0xc421daaa40, 0xc420f3f630, 0x0, 0x0, 0x0, 0x0)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/promql/engine.go:384 +0x1617
github.com/prometheus/prometheus/promql.(*Engine).exec(0xc420776b70, 0x5102298, 0xc421da9260, 0xc421daaa40, 0x0, 0x0, 0x0, 0x0)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/promql/engine.go:340 +0x3a0
github.com/prometheus/prometheus/promql.(*query).Exec(0xc421daaa40, 0x3bc4d58, 0xc421daa940, 0x3bc4d58)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/promql/engine.go:178 +0x9e
github.com/prometheus/prometheus/web/api/v1.(*API).query(0xc4200740c0, 0xc420830300, 0x0, 0x0, 0x0)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/web/api/v1/api.go:190 +0x32e
github.com/prometheus/prometheus/web/api/v1.(*API).(github.com/prometheus/prometheus/web/api/v1.query)-fm(0xc420830300, 0xc421db22e0, 0xc420f3f5e0, 0x3)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/web/api/v1/api.go:140 +0x34
github.com/prometheus/prometheus/web/api/v1.(*API).Register.func1.1(0x348b780, 0xc421db22e0, 0xc420830300)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/web/api/v1/api.go:125 +0x55
net/http.HandlerFunc.ServeHTTP(0xc4204a8810, 0x348b780, 0xc421db22e0, 0xc420830300)
	/usr/local/Cellar/go/1.8.3/libexec/src/net/http/server.go:1942 +0x44
github.com/prometheus/prometheus/util/httputil.CompressionHandler.ServeHTTP(0x3484140, 0xc4204a8810, 0x348c8c0, 0xc420f3f5e0, 0xc420830300)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/util/httputil/compression.go:90 +0x7c
github.com/prometheus/prometheus/util/httputil.(*CompressionHandler).ServeHTTP(0xc4204a8820, 0x348c8c0, 0xc420f3f5e0, 0xc420830300)
	<autogenerated>:5 +0x74
net/http.(Handler).ServeHTTP-fm(0x348c8c0, 0xc420f3f5e0, 0xc420830300)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/vendor/github.com/prometheus/client_golang/prometheus/http.go:182 +0x4d
github.com/prometheus/prometheus/vendor/github.com/prometheus/client_golang/prometheus.InstrumentHandlerFuncWithOpts.func1(0x348c800, 0xc421db22c0, 0xc420830300)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/vendor/github.com/prometheus/client_golang/prometheus/http.go:309 +0x224
github.com/prometheus/prometheus/vendor/github.com/prometheus/common/route.(*Router).handle.func1(0x348c800, 0xc421db22c0, 0xc420830200, 0x0, 0x0, 0x0)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/vendor/github.com/prometheus/common/route/route.go:50 +0x26a
github.com/prometheus/prometheus/vendor/github.com/julienschmidt/httprouter.(*Router).ServeHTTP(0xc42022e500, 0x348c800, 0xc421db22c0, 0xc420830200)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/vendor/github.com/julienschmidt/httprouter/router.go:299 +0x75d
github.com/prometheus/prometheus/vendor/github.com/prometheus/common/route.(*Router).ServeHTTP(0xc4204a71e0, 0x348c800, 0xc421db22c0, 0xc420830200)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/vendor/github.com/prometheus/common/route/route.go:88 +0x4c
net/http.StripPrefix.func1(0x348c800, 0xc421db22c0, 0xc420830200)
	/usr/local/Cellar/go/1.8.3/libexec/src/net/http/server.go:1977 +0xcf
net/http.HandlerFunc.ServeHTTP(0xc420b37f20, 0x348c800, 0xc421db22c0, 0xc420830200)
	/usr/local/Cellar/go/1.8.3/libexec/src/net/http/server.go:1942 +0x44
net/http.(*ServeMux).ServeHTTP(0xc4204a47e0, 0x348c800, 0xc421db22c0, 0xc420830200)
	/usr/local/Cellar/go/1.8.3/libexec/src/net/http/server.go:2238 +0x130
github.com/prometheus/prometheus/vendor/github.com/opentracing-contrib/go-stdlib/nethttp.Middleware.func2(0x3493f40, 0xc4201607e0, 0xc420830100)
	/Users/twilkie/Documents/src/github.com/prometheus/prometheus/vendor/github.com/opentracing-contrib/go-stdlib/nethttp/server.go:74 +0x45a
net/http.HandlerFunc.ServeHTTP(0xc420b37f80, 0x3493f40, 0xc4201607e0, 0xc420830100)
	/usr/local/Cellar/go/1.8.3/libexec/src/net/http/server.go:1942 +0x44
net/http.serverHandler.ServeHTTP(0xc4203b82c0, 0x3493f40, 0xc4201607e0, 0xc420830100)
	/usr/local/Cellar/go/1.8.3/libexec/src/net/http/server.go:2568 +0x92
net/http.(*conn).serve(0xc420c7a960, 0x3495a40, 0xc421a76a00)
	/usr/local/Cellar/go/1.8.3/libexec/src/net/http/server.go:1825 +0x612
created by net/http.(*Server).Serve
	/usr/local/Cellar/go/1.8.3/libexec/src/net/http/server.go:2668 +0x2ce
  source="engine.go:589"

[fabxc]

Fixed via #2946

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.