internal/poll: TestSplicePipePool failures on linux builders

[bcmills]

--- FAIL: TestSplicePipePool (1.07s)
    splice_linux_test.go:61: at least one pipe is still open
FAIL
FAIL	internal/poll	1.254s

2021-03-16T13:06:04-26c32de/linux-386-sid
2021-03-14T21:10:45-3cdd5c3/linux-arm

CC @panjf2000 @ianlancetaylor @bradfitz

[bcmills]

This test was added during the current release cycle (March 9, in CL 271537 for #42740), so marking as release-blocker for Go 1.17.

[panjf2000]

This looks more like an episodic failure?

[bcmills]

Yes, it is intermittent. An intermittent failure is nonetheless a failure.

[toothrot]

@bcmills @panjf2000 Friendly ping as this issue is labeled as a release-blocker for Go 1.17.

[bcmills]

@toothrot, I don't have the bandwidth to look into this at the moment. If no one else does either, then I suggest we roll back CL 271537 until it can be fixed.

[gopherbot]

Change https://golang.org/cl/308089 mentions this issue: Revert "internal/poll: implement a pipe pool for splice() call"

[ianlancetaylor]

2021-04-07T03:42:11-8462169/android-arm-corellium
2021-04-06T20:28:21-b56177a/android-arm-corellium
2021-03-30T23:55:42-0fdd371/android-arm-corellium
2021-03-26T06:03:20-98a9023/android-arm-corellium
2021-03-24T21:20:10-179bcd7/linux-arm
2021-03-18T19:15:12-e4253cd/android-arm-corellium
2021-03-18T18:50:58-b95e4b7/linux-arm
2021-03-17T22:14:28-f38b642/android-arm-corellium
2021-03-16T13:06:04-26c32de/linux-386-sid
2021-03-14T21:10:45-3cdd5c3/linux-arm

[gopherbot]

Change https://golang.org/cl/308329 mentions this issue: internal/poll: bump up the number of iterations in the test loop

[gopherbot]

Change https://golang.org/cl/317510 mentions this issue: internal/poll: cast off the last reference of SplicePipe in test