cmd/go: go test cached test times have increased 6x since Go 1.10 #26157
Comments
|
The regression occurred after 161874d |
|
git bisect suggests that ebb8a1f is potentially the cause. |
andybons
added
release-blocker
NeedsInvestigation
|
That change (https://golang.org/cl/115095) will definitely increase the time required for running tests for a package that has no tests. cmd/go will now build and run the test binary, when it didn't before. The question is: do we care? |
|
Even if it takes time to build and run the test binary, the result of building and running that binary should be cached; from the second set of timings, it appears that that is no longer the case. |
|
We cache compiler outputs, but as far as I know we don't cache linker outputs. When I run |
|
-count=n disables caching afaik
… On 3 Jul 2018, at 06:33, Ian Lance Taylor ***@***.***> wrote:
We cache compiler outputs, but as far as I know we don't cache linker outputs. When I run go test -test.count=1 bytes I see that it relinks bytes.test, even if it has been previously linked
—
You are receiving this because you authored the thread.
Reply to this email directly, view it on GitHub, or mute the thread.
|
|
|
|
What is the logic behind building a test binary then not running it?
…On 3 July 2018 at 10:23, Ian Lance Taylor ***@***.***> wrote:
-count=n disables the caching of the running of the test binary. It
doesn't disable the caching of the building of the test binary.
—
You are receiving this because you authored the thread.
Reply to this email directly, view it on GitHub
<#26157 (comment)>, or mute
the thread
<https://github.com/notifications/unsubscribe-auth/AAAcAyDRhtNl4djvzOQRP05GmydW3rJjks5uCrmagaJpZM4U99bT>
.
|
It's certainly possible that the inputs have changed in a way that doesn't change the test binary, in which case that is exactly what will happen. Still, you're right, it would be nice if we could skip building the test binary if the hash of the inputs points us to a cached test result. And maybe it is already supposed to work that way, I'm not sure. So I guess I was wrong in my comment above: there is something to do here. |
|
Duplicate (now) of #26242, which we will fix for Go 1.11. (To reply to Ian's comment, yes the implementation goes out of its way to avoid the compile + link if there's an up-to-date cached test result.) |
|
Change https://golang.org/cl/122518 mentions this issue: |
|
Thanks Russ!
… On 7 Jul 2018, at 03:32, Russ Cox ***@***.***> wrote:
Duplicate (now) of #26242, which we will fix for Go 1.11. (To reply to Ian's comment, yes the implementation goes out of its way to avoid the compile + link if there's an up-to-date cached test result.)
—
You are receiving this because you authored the thread.
Reply to this email directly, view it on GitHub, or mute the thread.
|
Original CL description:
When using test -cover or -coverprofile the output for "no test files"
is the same format as for "no tests to run".
Reverting because this CL changed cmd/go to build test binaries for
packages that have no tests, leading to extra work and confusion.
Updates #24570
Fixes #25789
Fixes #26157
Fixes #26242
Change-Id: Ibab1307d39dfaec0de9359d6d96706e3910c8efd
Reviewed-on: https://go-review.googlesource.com/122518
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Please answer these questions before submitting your issue. Thanks!
What version of Go are you using (
go version)?go version devel +da769814b8 Fri Jun 29 23:22:48 2018 +0000 darwin/amd64
Does this issue reproduce with the latest release?
No, this is a regression from Go 1.10.3
What operating system and processor architecture are you using (
go env)?darwin/amd64
What did you do?
I recently updated to the latest master branch, I hadn't updated for a month or so, and found that go test times for a project with mostly cached tests have increased from less than a second to near 6 seconds.
What did you expect to see?
time go1.10 test ./...andtime go test ./...should be equivalentWhat did you see instead?
Time to run cached tests under Go 1.10
Time to run cached tests under Go tip
The text was updated successfully, but these errors were encountered: