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cmd/go: coverage profile should be cached with tests #23565
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CC @rsc |
Change https://golang.org/cl/90955 mentions this issue: |
I was hoping this change would make it into go1.11 but it seems its not working yet in |
@fgrosse Looks like it's being targeted for 1.12 now. I don't think it will be rescheduled this close to 1.11's release. |
Alright, thanks for the update on this issue.
Ben Brooks <[email protected]> schrieb am Mo., 6. Aug. 2018, 13:34:
… @fgrosse <https://github.com/fgrosse> Looks like it's being targeted for
1.12 now. I don't think it will be rescheduled this close to 1.11's release.
—
You are receiving this because you were mentioned.
Reply to this email directly, view it on GitHub
<#23565 (comment)>, or mute
the thread
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.
|
Is this still planned for Go1.12 ? I guess not... |
It wasn't used and it prevents tests from being cached. See golang/go#23565 for more details.
It wasn't used and it prevents tests from being cached. See golang/go#23565 for more details.
It wasn't used and it prevents tests from being cached. See golang/go#23565 for more details.
It wasn't used and it prevents tests from being cached. See golang/go#23565 for more details.
Any updates on this? Thanks |
Any plans on this? We have a huge go monorepo and this prevents us from leveragin test cache in our tooling. |
Is this something that could be still implemented or is the idea abandoned? |
This is a feature I'd love to see make it into go one day. We run our unit tests against a large monorepo and would like to be able to generate a coverage report for every PR but it's not feasible to do for the entire repo if the test results aren't cached. |
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Fixes golang#23565
If some job is not a build bottleneck - let's remove caching. The main focus points then are "build" and "race" then. To cache test results independently let's use 2 different cache prefixes. See https://markphelps.me/posts/speed-up-your-go-builds-with-actions-cache/. The idea is to always generate cash miss using the second precision key. After the miss we download latest uploaded one using "restore-keys". Potential improvements: 1. golang/go#23565 asks to cache -coverprofile results since 2018. 2. golang/go#61608 to cache -race results.
Could we, at least, add a note that test cache doesn't work with Maybe here would be the proper place? |
If some job is not a build bottleneck - let's remove caching. The main focus points then are "build" and "race" then. To cache test results independently let's use 2 different cache prefixes. See https://markphelps.me/posts/speed-up-your-go-builds-with-actions-cache/. The idea is to always generate cash miss using the second precision key. After the miss we download latest uploaded one using "restore-keys". Potential improvements: 1. golang/go#23565 asks to cache -coverprofile results since 2018. 2. golang/go#61608 to cache -race results.
'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Fixes golang#23565 Co-authored-by: James Roberts <[email protected]>
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Fixes golang#23565 Co-authored-by: James Roberts <[email protected]>
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Fixes golang#23565 Co-authored-by: James Roberts <[email protected]>
Change https://go.dev/cl/563138 mentions this issue: |
'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Fixes golang#23565 Co-authored-by: James Roberts <[email protected]>
'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Fixes golang#23565 Co-authored-by: James Roberts <[email protected]>
I agree with the ChangeList comment—this enhancement does more than just save developer time; it also offers significant environmental benefits. I urge the Go development team to consider this matter with the gravity it deserves. While I understand that it may not be as appealing as a new feature or a runtime issue, and thus might not be prioritized as highly, it nonetheless warrants serious consideration. |
@macnibblet you have some feedback on the CL. Not sure if you got notified. |
@ryancurrah I have, but I have been swamped with work, but this is still high up on my to do list. |
@macnibblet Brian, who is reviewing your CR is leaving Google. Maybe if we can get the CR comments addressed we can get it merged before he leaves. I have addressed his comments in my diff. diff --git a/src/cmd/go/alldocs.go b/src/cmd/go/alldocs.go
index dde47ac1b8..f45a85256a 100644
--- a/src/cmd/go/alldocs.go
+++ b/src/cmd/go/alldocs.go
@@ -1803,8 +1803,9 @@
//
// The rule for a match in the cache is that the run involves the same
// test binary and the flags on the command line come entirely from a
-// restricted set of 'cacheable' test flags, defined as -benchtime, -cpu,
-// -list, -parallel, -run, -short, -timeout, -failfast, -fullpath and -v.
+// restricted set of 'cacheable' test flags, defined as -benchtime, -cover,
+// -covermode, -coverprofile, -cpu, -list, -parallel, -run, -short, -timeout,
+// -failfast, -fullpath and -v.
// If a run of go test has any test or non-test flags outside this set,
// the result is not cached. To disable test caching, use any test flag
// or argument other than the cacheable flags. The idiomatic way to disable
diff --git a/src/cmd/go/internal/test/cover.go b/src/cmd/go/internal/test/cover.go
index f614458dc4..461b60c3ca 100644
--- a/src/cmd/go/internal/test/cover.go
+++ b/src/cmd/go/internal/test/cover.go
@@ -16,7 +16,8 @@ import (
var coverMerge struct {
f *os.File
- sync.Mutex // for f.Write
+ fsize int64 // size of valid data written to f
+ sync.Mutex // for f.Write
}
// initCoverProfile initializes the test coverage profile.
@@ -36,18 +37,19 @@ func initCoverProfile() {
if err != nil {
base.Fatalf("%v", err)
}
- _, err = fmt.Fprintf(f, "mode: %s\n", cfg.BuildCoverMode)
+ s, err := fmt.Fprintf(f, "mode: %s\n", cfg.BuildCoverMode)
if err != nil {
base.Fatalf("%v", err)
}
coverMerge.f = f
+ coverMerge.fsize += int64(s)
}
// mergeCoverProfile merges file into the profile stored in testCoverProfile.
// It prints any errors it encounters to ew.
-func mergeCoverProfile(ew io.Writer, file string) {
+func mergeCoverProfile(file string) error {
if coverMerge.f == nil {
- return
+ return nil
}
coverMerge.Lock()
defer coverMerge.Unlock()
@@ -57,28 +59,33 @@ func mergeCoverProfile(ew io.Writer, file string) {
r, err := os.Open(file)
if err != nil {
// Test did not create profile, which is OK.
- return
+ return nil
}
defer r.Close()
n, err := io.ReadFull(r, buf)
if n == 0 {
- return
+ return nil
}
if err != nil || string(buf) != expect {
- fmt.Fprintf(ew, "error: test wrote malformed coverage profile %s.\n", file)
- return
+ return fmt.Errorf("error: test wrote malformed coverage profile %s: %w", file, err)
}
_, err = io.Copy(coverMerge.f, r)
if err != nil {
- fmt.Fprintf(ew, "error: saving coverage profile: %v\n", err)
+ return fmt.Errorf("error: saving coverage profile: %w", err)
}
+
+ return nil
}
func closeCoverProfile() {
if coverMerge.f == nil {
return
}
+ // Discard any partially written data from a failed merge.
+ if err := coverMerge.f.Truncate(coverMerge.fsize); err != nil {
+ base.Errorf("closing coverage profile: %v", err)
+ }
if err := coverMerge.f.Close(); err != nil {
base.Errorf("closing coverage profile: %v", err)
}
diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
index 08fac5f395..f877d27c1a 100644
--- a/src/cmd/go/internal/test/test.go
+++ b/src/cmd/go/internal/test/test.go
@@ -126,8 +126,9 @@ elapsed time in the summary line.
The rule for a match in the cache is that the run involves the same
test binary and the flags on the command line come entirely from a
-restricted set of 'cacheable' test flags, defined as -benchtime, -cpu,
--list, -parallel, -run, -short, -timeout, -failfast, -fullpath and -v.
+restricted set of 'cacheable' test flags, defined as -benchtime, -cover,
+-covermode, -coverprofile, -cpu, -list, -parallel, -run, -short, -timeout,
+-failfast, -fullpath and -v.
If a run of go test has any test or non-test flags outside this set,
the result is not cached. To disable test caching, use any test flag
or argument other than the cacheable flags. The idiomatic way to disable
@@ -1337,6 +1338,13 @@ type runCache struct {
id2 cache.ActionID
}
+func coverProfTempFile(a *work.Action) string {
+ if a.Objdir == "" {
+ panic("internal error: objdir not set in coverProfTempFile")
+ }
+ return a.Objdir + "_cover_.out"
+}
+
// stdoutMu and lockedStdout provide a locked standard output
// that guarantees never to interlace writes from multiple
// goroutines, so that we can have multiple JSON streams writing
@@ -1395,13 +1403,6 @@ func (r *runTestActor) Act(b *work.Builder, ctx context.Context, a *work.Action)
return nil
}
- coverProfTempFile := func(a *work.Action) string {
- if a.Objdir == "" {
- panic("internal error: objdir not set in coverProfTempFile")
- }
- return a.Objdir + "_cover_.out"
- }
-
if p := a.Package; len(p.TestGoFiles)+len(p.XTestGoFiles) == 0 {
reportNoTestFiles := true
if cfg.BuildCover && cfg.Experiment.CoverageRedesign && p.Internal.Cover.GenMeta {
@@ -1425,7 +1426,7 @@ func (r *runTestActor) Act(b *work.Builder, ctx context.Context, a *work.Action)
if err := work.WriteCoverageProfile(b, a, mf, cp, stdout); err != nil {
return err
}
- mergeCoverProfile(stdout, cp)
+ if err = mergeCoverProfile(cp); err != nil {
+ return err
+ }
}
}
}
@@ -1615,7 +1616,9 @@ func (r *runTestActor) Act(b *work.Builder, ctx context.Context, a *work.Action)
a.TestOutput = &buf
t := fmt.Sprintf("%.3fs", time.Since(t0).Seconds())
- mergeCoverProfile(cmd.Stdout, a.Objdir+"_cover_.out")
+ if coverErr := mergeCoverProfile(a.Objdir + "_cover_.out"); coverErr != nil {
+ return coverErr
+ }
if err == nil {
norun := ""
@@ -1637,7 +1640,7 @@ func (r *runTestActor) Act(b *work.Builder, ctx context.Context, a *work.Action)
cmd.Stdout.Write([]byte("\n"))
}
fmt.Fprintf(cmd.Stdout, "ok \t%s\t%s%s%s\n", a.Package.ImportPath, t, coveragePercentage(out), norun)
- r.c.saveOutput(a)
+ r.c.saveOutput(a, coverProfTempFile(a))
} else {
if testFailFast {
testShouldFailFast.Store(true)
@@ -1735,6 +1738,18 @@ func (c *runCache) tryCacheWithID(b *work.Builder, a *work.Action, id string) bo
// Note that this list is documented above,
// so if you add to this list, update the docs too.
cacheArgs = append(cacheArgs, arg)
+ case "-test.coverprofile",
+ "-test.outputdir":
+ // The `-coverprofile` and `-outputdir` arguments, which
+ // only affect the location of profile output, are cacheable. This
+ // is based on the process where, upon a cache hit, stored profile
+ // data is copied to the specified output location. This mechanism
+ // ensures that output location preferences are honored without
+ // modifying the profile's content, thereby justifying their
+ // cacheability without impacting cache integrity. This allows
+ // cached coverage profiles to be written to different files.
+ // Note that this list is documented above,
+ // so if you add to this list, update the docs too.
default:
// nothing else is cacheable
@@ -1847,6 +1862,26 @@ func (c *runCache) tryCacheWithID(b *work.Builder, a *work.Action, id string) bo
j++
}
c.buf.Write(data[j:])
+
+ // Write coverage data to profile.
+ if cfg.BuildCover {
+ // The cached coverprofile has the same expiration time as the
+ // test result it corresponds to. That time is already checked
+ // above, so we can ignore the entry returned by GetFile here.
+ f, _, err := cache.GetFile(cache.Default(), testCoverProfileKey(testID, testInputsID))
+ if err != nil {
+ if cache.DebugTest {
+ fmt.Fprintf(os.Stderr, "testcache: %s: test coverage profile not found: %v\n", a.Package.ImportPath, err)
+ }
+ return false
+ }
+ if err := mergeCoverProfile(f); err != nil {
+ if cache.DebugTest {
+ fmt.Fprintf(os.Stderr, "testcache: %s: test coverage profile not merged: %v\n", a.Package.ImportPath, err)
+ }
+ return false
+ }
+ }
return true
}
@@ -1993,7 +2028,12 @@ func testAndInputKey(testID, testInputsID cache.ActionID) cache.ActionID {
return cache.Subkey(testID, fmt.Sprintf("inputs:%x", testInputsID))
}
-func (c *runCache) saveOutput(a *work.Action) {
+// testCoverProfileKey returns the "coverprofile" cache key for the pair (testID, testInputsID).
+func testCoverProfileKey(testID, testInputsID cache.ActionID) cache.ActionID {
+ return cache.Subkey(testAndInputKey(testID, testInputsID), "coverprofile")
+}
+
+func (c *runCache) saveOutput(a *work.Action, coverprofileFile string) {
if c.id1 == (cache.ActionID{}) && c.id2 == (cache.ActionID{}) {
return
}
@@ -2014,12 +2054,29 @@ func (c *runCache) saveOutput(a *work.Action) {
if err != nil {
return
}
+ saveCoverProfile := func(testID cache.ActionID) {}
+ if coverprofileFile != "" {
+ coverprof, err := os.Open(coverprofileFile)
+ if err == nil {
+ saveCoverProfile = func(testID cache.ActionID) {
+ cache.Default().Put(testCoverProfileKey(testID, testInputsID), coverprof)
+ }
+ defer func() {
+ if err := coverprof.Close(); err != nil && cache.DebugTest {
+ fmt.Fprintf(os.Stderr, "testcache: %s: closing temporary coverprofile: %v", a.Package.ImportPath, err)
+ }
+ }()
+ } else if cache.DebugTest {
+ fmt.Fprintf(os.Stderr, "testcache: %s: failed to open temporary coverprofile: %s", a.Package.ImportPath, err)
+ }
+ }
if c.id1 != (cache.ActionID{}) {
if cache.DebugTest {
fmt.Fprintf(os.Stderr, "testcache: %s: save test ID %x => input ID %x => %x\n", a.Package.ImportPath, c.id1, testInputsID, testAndInputKey(c.id1, testInputsID))
}
cache.PutNoVerify(cache.Default(), c.id1, bytes.NewReader(testlog))
cache.PutNoVerify(cache.Default(), testAndInputKey(c.id1, testInputsID), bytes.NewReader(a.TestOutput.Bytes()))
+ saveCoverProfile(c.id1)
}
if c.id2 != (cache.ActionID{}) {
if cache.DebugTest {
@@ -2027,6 +2084,7 @@ func (c *runCache) saveOutput(a *work.Action) {
}
cache.PutNoVerify(cache.Default(), c.id2, bytes.NewReader(testlog))
cache.PutNoVerify(cache.Default(), testAndInputKey(c.id2, testInputsID), bytes.NewReader(a.TestOutput.Bytes()))
+ saveCoverProfile(c.id2)
}
}
diff --git a/src/cmd/go/testdata/script/test_cache_inputs.txt b/src/cmd/go/testdata/script/test_cache_inputs.txt
index 3705c700d1..1e9ed4cc93 100644
--- a/src/cmd/go/testdata/script/test_cache_inputs.txt
+++ b/src/cmd/go/testdata/script/test_cache_inputs.txt
@@ -114,6 +114,32 @@ go test testcache -run=TestOSArgs -failfast
go test testcache -run=TestOSArgs -failfast
stdout '\(cached\)'
+# Ensure that specifying a cover profile does not prevent test results from being cached.
+go test testcache -run=none -coverprofile=cover.out
+! stdout '\(cached\)'
+go test testcache -run=none -coverprofile=cover.out
+stdout '\(cached\)'
+
+# A new -coverprofile file should use the cached coverage profile contents.
+go test testcache -run=none -coverprofile=cover.out
+go test testcache -run=none -coverprofile=cover1.out
+stdout '\(cached\)'
+
+# Cached coverage profile contents should be the same as the first result.
+go test testcache -run=none -coverprofile=cover.out
+go test testcache -run=none -coverprofile=cover1.out
+cmp cover.out cover1.out
+
+# A new -covermode should not use the cached coverage profile.
+go test testcache -run=none -coverprofile=cover.out
+go test testcache -run=none -covermode=count -coverprofile=cover.out
+! stdout '\(cached\)'
+
+# A new -coverpkg should not use the cached coverage profile.
+go test testcache -run=none -coverprofile=cover.out
+go test testcache -run=none -coverpkg=math -coverprofile=cover.out
+! stdout '\(cached\)'
+
# Executables within GOROOT and GOPATH should affect caching,
# even if the test does not stat them explicitly.
|
I am willing to pitch in with reviews etc as well if you think it would help. Thanks. |
This is such a long-lasting painful issue 😭 For years, so close to solution, yet so far. |
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Note: This is a rebase and squash from the original PRs golang#50483 and golang#65657 that was created/closed by @jproberts and @macnibblet that I plan to maintain. I made improvements to the PR based on feedback from @bcmills. From @macnibblet: I don't know if anyone has considered the environmental impact (Yes, of course, dev experience too), but on a team with 3 backend developers, when I replaced our CI Golang version with this build, it reduced the build time by 50%, which would have equated to about 5000 hours of CI reduced in the past year. Fixes golang#23565 Signed-off-by: Ryan Currah <[email protected]>
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Note: This is a rebase and squash from the original PRs golang#50483 and golang#65657 that was created/closed/abandoned by @jproberts and @macnibblet that I plan to maintain. I made improvements to the PR based on feedback from @bcmills here https://go-review.googlesource.com/c/go/+/563138. y From @macnibblet: I don't know if anyone has considered the environmental impact (Yes, of course, dev experience too), but on a team with 3 backend developers, when I replaced our CI Golang version with this build, it reduced the build time by 50%, which would have equated to about 5000 hours of CI reduced in the past year. Fixes golang#23565 Signed-off-by: Ryan Currah <[email protected]>
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Note: This is a rebase and squash from the original PRs golang#50483 and golang#65657 that was created/closed/abandoned by @jproberts and @macnibblet that I plan to maintain. I made improvements to the PR based on feedback from @bcmills here https://go-review.googlesource.com/c/go/+/563138. From @macnibblet: I don't know if anyone has considered the environmental impact (Yes, of course, dev experience too), but on a team with 3 backend developers, when I replaced our CI Golang version with this build, it reduced the build time by 50%, which would have equated to about 5000 hours of CI reduced in the past year. Fixes golang#23565 Signed-off-by: Ryan Currah <[email protected]>
Change https://go.dev/cl/610564 mentions this issue: |
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Note: This is a rebase and squash from the original PRs golang#50483 and golang#65657 that was created/closed/abandoned by @jproberts and @macnibblet that I plan to maintain. I made improvements to the PR based on feedback from @bcmills here https://go-review.googlesource.com/c/go/+/563138. From @macnibblet: I don't know if anyone has considered the environmental impact (Yes, of course, dev experience too), but on a team with 3 backend developers, when I replaced our CI Golang version with this build, it reduced the build time by 50%, which would have equated to about 5000 hours of CI reduced in the past year. Fixes golang#23565 Signed-off-by: Ryan Currah <[email protected]>
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Note: This is a rebase and squash from the original PRs below that was created/closed/abandoned by @jproberts and @macnibblet that I plan to maintain. - golang#50483 - golang#65657 I made improvements to the change based on feedback from @bcmills in Gerrit https://go-review.googlesource.com/c/go/+/563138. From @macnibblet: I don't know if anyone has considered the environmental impact (Yes, of course, dev experience too), but on a team with 3 backend developers, when I replaced our CI Golang version with this build, it reduced the build time by 50%, which would have equated to about 5000 hours of CI reduced in the past year. Fixes golang#23565
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Note: This is a rebase and squash from the original PRs below that was created/closed/abandoned by @jproberts and @macnibblet that I plan to maintain. - golang#50483 - golang#65657 I made improvements to the change based on feedback from @bcmills in Gerrit https://go-review.googlesource.com/c/go/+/563138. From @macnibblet: I don't know if anyone has considered the environmental impact (Yes, of course, dev experience too), but on a team with 3 backend developers, when I replaced our CI Golang version with this build, it reduced the build time by 50%, which would have equated to about 5000 hours of CI reduced in the past year. Fixes golang#23565
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Note: This is a rebase and squash from the original PRs below that was created/closed/abandoned by @jproberts and @macnibblet that I plan to maintain. - golang#50483 - golang#65657 I made improvements to the change based on feedback from @bcmills in Gerrit https://go-review.googlesource.com/c/go/+/563138. From @macnibblet: I don't know if anyone has considered the environmental impact (Yes, of course, dev experience too), but on a team with 3 backend developers, when I replaced our CI Golang version with this build, it reduced the build time by 50%, which would have equated to about 5000 hours of CI reduced in the past year. Fixes golang#23565
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Note: This is a rebase and squash from the original PRs below that was created/closed/abandoned by @jproberts and @macnibblet that I plan to maintain. - golang#50483 - golang#65657 I made improvements to the change based on feedback from @bcmills in Gerrit https://go-review.googlesource.com/c/go/+/563138. From @macnibblet: I don't know if anyone has considered the environmental impact (Yes, of course, dev experience too), but on a team with 3 backend developers, when I replaced our CI Golang version with this build, it reduced the build time by 50%, which would have equated to about 5000 hours of CI reduced in the past year. Fixes golang#23565
This CL stores coverage profile data in the GOCACHE under the 'coverprofile' subkey alongside tests. This makes tests which use coverage profiles cacheable. The values of the -coverprofile and -outputdir flags are not included in the cache key to allow cached profile data to be written to any output file. Note: This is a rebase and squash from the original PRs below that was created/closed/abandoned by @jproberts and @macnibblet that I plan to maintain. - golang#50483 - golang#65657 I made improvements to the change based on feedback from @bcmills in Gerrit https://go-review.googlesource.com/c/go/+/563138. From @macnibblet: I don't know if anyone has considered the environmental impact (Yes, of course, dev experience too), but on a team with 3 backend developers, when I replaced our CI Golang version with this build, it reduced the build time by 50%, which would have equated to about 5000 hours of CI reduced in the past year. Fixes golang#23565
As briefly discussed here: https://twitter.com/_rsc/status/956888213314068481
I don't see why Go shouldn't cache the results of
-coverprofile
when running tests, as test coverage shouldn't vary from run to run, given the same set of arguments.What version of Go are you using (
go version
)?go version go1.10rc1 darwin/amd64
Does this issue reproduce with the latest release?
Yes
What operating system and processor architecture are you using (
go env
)?What did you do?
Call
go test -coverprofile=coverprofile.out ./...
multiple times.What did you expect to see?
Test results cached between runs.
What did you see instead?
Test results were not cached between runs.
The text was updated successfully, but these errors were encountered: