Error map
fatal error: concurrent map writes Go: fatal error: concurrent map writes
Go · layer 4, Application & API
Centre: this error. First ring: errors it is linked with (7). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (7)
Go: cannot assign to struct field users["bob"].Age in map
Map values are not addressable, so you cannot modify a field of a struct stored directly in a map.
Go: panic: assignment to entry in nil map
You wrote to a map that was declared but never initialised.
Go: fatal error: concurrent map read and map write
One goroutine read from a map while another wrote to it; the runtime aborts.
Go: panic: send on closed channel
A goroutine sent a value to a channel after it had been closed.
Go: panic: close of closed channel (or close of nil channel)
`close(ch)` was called twice, or on a nil channel.
Go: panic: sync: negative WaitGroup counter
`wg.Done()` was called more times than `wg.Add()`.
Go: WARNING: DATA RACE — Write at 0x00c0000 by goroutine 7: / Previous read at ... by goroutine 6
The race detector (`-race`) observed two goroutines accessing the same memory concurrently with at least one write and no synchro…
Two steps away (10)
Go: ./main.go:5:2: "os" imported and not used
The file imports a package that no code in that file uses; Go treats this as a compile error, not a warning.
Go: ./main.go:12:2: undefined: handler
The compiler cannot find an identifier — a typo, a missing import, or it lives in another file/package that wasn't built.
Go: ./main.go:18:1: missing return
A function with a return type can reach its end without a return statement on some path.
Go: panic: runtime error: invalid memory address or nil pointer dereference
The program used a pointer, map, interface or struct field that was nil — usually an uninitialised value or an ignored error.
Go: panic: runtime error: index out of range [3] with length 3
Code accessed a slice, array or string element beyond its length.
Go: panic: runtime error: slice bounds out of range [:5] with capacity 3
A slice expression `s[a:b]` used bounds outside the slice's length or capacity.
Go: fatal error: all goroutines are asleep - deadlock!
Every goroutine is blocked waiting (on a channel, mutex or WaitGroup), so the program can never continue.
Go: context canceled (rpc error: code = Canceled desc = context canceled)
The context was cancelled before the operation finished — the caller gave up, the client disconnected, or a parent was cancelled.
Go: listen tcp :8080: bind: address already in use
The port your Go server wants is already taken by another process (or a previous instance of your app).
Go: panic: test timed out after 10m0s — running tests: TestFoo (10m0s)
`go test` killed the test binary because it exceeded the timeout (default 10 minutes), usually a hung test.
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