testing: No way to view untruncated output from benchmarks

[Minnozz]

What version of Go are you using (go version)?

go version go1.10.3 linux/amd64

Does this issue reproduce with the latest release?

Unknown, but the documentation has not changed.

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOCACHE="/home/barts/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/barts/go"
GORACE=""
GOROOT="/usr/lib/go-1.10"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go-1.10/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build014311929=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I'm running a benchmark with the verbose flag turned on (go test -bench . -v) that calls b.Logf() multiple times.

What did you expect to see?

All logging output, like with tests.

What did you see instead?

The first few log calls, followed by ... [output truncated])

[katiehockman]

/cc @mpvl

[Minnozz]

Truncating happens in testing.B.trimOutput(), called by testing.RunBenchmarks().

[EnchanterIO]

@Minnozz did you find out how to avoid truncating? Not sure how this behavior can be useful because if I log something in my benchmark... it's to read it when the benchmark finishes.

I guess this is done for performance reasons? Maybe if it would get done async it wouldn't be a problem? But I would say definitely optional.

[EnchanterIO]

Checking more the benchmark code, the maxNewLines could be 10 by default but configurable not hardcoded.