runtime: invalid pointer found on stack regression in Go1.15 triggered by mapassign in init #41816
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The problem is in the generated code for that init function. The bad pointer was found at This doesn't necessarily have anything to do with maps. A map operation just happened to be the thing that triggered a stack copy. What else is in that init function? It would be really nice if we could see it... |
martisch
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odeke-em
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@randall77 with identifiers renamed: type itemPair struct {
a schema.Item
b schema.Item
}
var uuidToPair = make(map[string]itemPair)
func init() {
now := time.Now().UTC()
specialA := datapkg.LookupItem(SpecialStrConstA)
specialB := datapkg.LookupItem(SpecialStrConstB)
items := datapkg.ListItems()
items = datapkg.FilterItemsByTime(items, now)
for _, v := range items {
itemUUID := v.Attrs.UUID
if itemUUID == "" {
continue
}
if isTypeB(v) {
pair := itemPair{a: specialA, b: v}
uuidToPair[itemUUID] = pair
for _, uuid := range v.Attrs.AuxUUIDs {
pair = uuidToPair[uuid]
pair.b = v
uuidToPair[uuid] = pair
}
continue
}
pair := itemPair{a: v, b: specialB}
uuidToPair[itemUUID] = pair
for _, uuid := range v.Attrs.AuxUUIDs {
pair = uuidToPair[uuid]
pair.a = v
uuidToPair[uuid] = pair // <-- this is where the panic/throw occurred
}
}
} |
ianlancetaylor
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Hm, nothing obviously bad. |
ianlancetaylor
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WaitingForInfo
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Timed out in state WaitingForInfo. Closing. (I am just a bot, though. Please speak up if this is a mistake or you have the requested information.) |
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What version of Go are you using (
go version)?Does this issue reproduce with the latest release?
Yes (this is the latest release).
What operating system and processor architecture are you using (
go env)?docker pull golang:1.15(as of Oct 6, 2020).go envOutputWhat did you do?
Run
go teston the same code that had been working from 1.10 through 1.14.The
<scrubbed>:91line in the stack trace refers to a map assignment within an init function. The map is declared in the global scope, and is a map of string keys to large (several hundred byte) struct values. The map was initialized at declaration time usingmakewithout an explicit capacity hint.What did you expect to see?
no panic/throw.
What did you see instead?
Repeatable, but not deterministic (happens 33% of the time) failures of the form:
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