SetUpTest first initializes the lastStack to nil, but wasn't doing so using
the stackMu. This should be a reasonable fix:
--- a/apiserver/logsink/logsink_test.go
+++ b/apiserver/logsink/logsink_test.go
@@ -60,7 +60,9 @@ func (s *logsinkSuite) SetUpTest(c *gc.C) {
        s.abort = make(chan struct{})
        s.written = make(chan params.LogRecord, 1)
        s.stub.ResetCalls()
+       s.stackMu.Lock()
        s.lastStack = nil
+       s.stackMu.Unlock()

        recordStack := func() {
                s.stackMu.Lock()

On Wed, Mar 14, 2018 at 4:11 PM, John A Meinel <email address hidden>
wrote:

> Public bug reported:
>
> github.com/juju/juju/apiserver/logsink_test.(*logsinkSuite).SetUpTest has
> a Data Race in develop:
> http://10.125.0.203:8080/job/RunUnittests-race-amd64/182/
> testReport/junit/github/com_juju_juju_apiserver_logsink/TestPackage/
>
> WARNING: DATA RACE
> Write at 0x00c4200d0210 by goroutine 70:
>   github.com/juju/juju/apiserver/logsink_test.(*
> logsinkSuite).SetUpTest.func1()
>       /workspace/src/github.com/juju/juju/apiserver/logsink/
> logsink_test.go:68 +0xc1
>   github.com/juju/juju/apiserver/logsink_test.(*
> mockLogWriteCloser).Close()
>       /workspace/src/github.com/juju/juju/apiserver/logsink/
> logsink_test.go:265 +0x129
>   github.com/juju/juju/apiserver/logsink.(*logSinkHandler).ServeHTTP.
> func1()
>       /workspace/src/github.com/juju/juju/apiserver/logsink/logsink.go:163
> +0x5c3
>   github.com/juju/juju/apiserver/websocket.Serve()
>       /workspace/src/github.com/juju/juju/apiserver/websocket/
> websocket.go:64 +0x1b1
>   github.com/juju/juju/apiserver/logsink.(*logSinkHandler).ServeHTTP()
>       /workspace/src/github.com/juju/juju/apiserver/logsink/logsink.go:168
> +0xba
>   net/http.serverHandler.ServeHTTP()
>       /snap/go/1404/src/net/http/server.go:2619 +0xbc
>   net/http.(*conn).serve()
>       /snap/go/1404/src/net/http/server.go:1801 +0x83b
>
> Previous write at 0x00c4200d0210 by goroutine 75:
>   github.com/juju/juju/apiserver/logsink_test.(*logsinkSuite).SetUpTest()
>       /workspace/src/github.com/juju/juju/apiserver/logsink/
> logsink_test.go:63 +0x165
>   runtime.call32()
>       /snap/go/1404/src/runtime/asm_amd64.s:509 +0x3a
>   reflect.Value.Call()
>       /snap/go/1404/src/reflect/value.go:302 +0xc0
>   gopkg.in/check%2ev1.(*suiteRunner).runFixture.func1()
>       /workspace/src/gopkg.in/check.v1/check.go:721 +0x184
>   gopkg.in/check%2ev1.(*suiteRunner).forkCall.func1()
>       /workspace/src/gopkg.in/check.v1/check.go:666 +0x89
>
> Goroutine 70 (running) created at:
>   net/http.(*Server).Serve()
>       /snap/go/1404/src/net/http/server.go:2720 +0x37c
>   net/http/httptest.(*Server).goServe.func1()
>       /snap/go/1404/src/net/http/httptest/server.go:280 +0xa2
>
> Goroutine 75 (finished) created at:
>   gopkg.in/check%2ev1.(*suiteRunner).forkCall()
>       /workspace/src/gopkg.in/check.v1/check.go:663 +0x430
>   gopkg.in/check%2ev1.(*suiteRunner).runFunc()
>       /workspace/src/gopkg.in/check.v1/check.go:673 +0x7e
>   gopkg.in/check%2ev1.(*suiteRunner).runFixture()
>       /workspace/src/gopkg.in/check.v1/check.go:717 +0x7e
>   gopkg.in/check%2ev1.(*suiteRunner).runFixtureWithPanic()
>       /workspace/src/gopkg.in/check.v1/check.go:735 +0xaa
>   gopkg.in/check%2ev1.(*suiteRunner).forkTest.func1()
>       /workspace/src/gopkg.in/check.v1/check.go:760 +0x217
>   gopkg.in/check%2ev1.(*suiteRunner).forkCall.func1()
>       /workspace/src/gopkg.in/check.v1/check.go:666 +0x89
> ==================
> OK: 6 passed
>         testing.go:699: race detected during execution of test
>
> ** Affects: juju
>      Importance: High
>      Assignee: John A Meinel (jameinel)
>          Status: In Progress
>
>
> ** Tags: intermittent-failure race-condition
>
> ** Changed in: juju
>        Status: Triaged => In Progress
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1755796
>
> Title:
>   (*logsinkSuite).SetUpTest data race
>
> To manage notifications about this bug go to:
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>