*: make test is failed about cgroup

[lhy1024]

Bug Report

What did you do?

make test

What did you expect to see?

success

What did you see instead?

failed after #5848 merged

--- FAIL: TestGetCgroupCPU (0.00s)
    cgroup_cpu_test.go:45: 
                Error Trace:    /home/lhy1024/pd/pkg/cgroup/cgroup_cpu_test.go:45
                Error:          Received unexpected error:
                                no cpu controller detected
                                github.com/tikv/pd/pkg/cgroup.getCgroupCPUHelper
                                        /home/lhy1024/pd/pkg/cgroup/cgroup_cpu.go:33
                                github.com/tikv/pd/pkg/cgroup.GetCgroupCPU
                                        /home/lhy1024/pd/pkg/cgroup/cgroup_cpu_linux.go:28
                                github.com/tikv/pd/pkg/cgroup.TestGetCgroupCPU
                                        /home/lhy1024/pd/pkg/cgroup/cgroup_cpu_test.go:44
                                testing.tRunner
                                        /usr/local/go/src/testing/testing.go:1446
                                runtime.goexit
                                        /usr/local/go/src/runtime/asm_amd64.s:1594
                Test:           TestGetCgroupCPU
[2023/02/09 14:11:28.732 +08:00] [WARN] [cgroup_memory.go:84] ["no cgroup memory controller detected"]
[2023/02/09 14:11:28.780 +08:00] [WARN] [cgroup_memory.go:55] ["no cgroup memory controller detected"]
[2023/02/09 14:11:28.796 +08:00] [WARN] [cgroup_memory.go:115] ["no cgroup memory controller detected"]
FAIL
coverage: 76.5% of statements
FAIL    github.com/tikv/pd/pkg/cgroup   0.184s

--- FAIL: TestFinalizer (0.01s)
    finalizer_test.go:40: 
                Error Trace:    /home/lhy1024/pd/pkg/gctuner/finalizer_test.go:40
                Error:          Not equal: 
                                expected: 1
                                actual  : 0
                Test:           TestFinalizer
[2023/02/09 14:18:20.957 +08:00] [INFO] [memory_limit_tuner.go:49] [debug.SetMemoryLimit] [limit=858993459] [ret=9223372036854775807]
[2023/02/09 14:18:21.022 +08:00] [INFO] [memory_limit_tuner.go:49] [debug.SetMemoryLimit] [limit=1181116006] [ret=858993459]
[2023/02/09 14:18:23.825 +08:00] [INFO] [tuner.go:117] ["new gctuner"] [threshold=524288000]
[2023/02/09 14:18:23.826 +08:00] [INFO] [gogc.go:43] [debug.SetGCPercent] [val=500] [result=100]
panic: Fail in goroutine after TestFinalizer has completed

goroutine 20 [running]:
testing.(*common).Fail(0xc000248680)
        /usr/local/go/src/testing/testing.go:824 +0x1a8
testing.(*common).FailNow(0xc000248680)
        /usr/local/go/src/testing/testing.go:847 +0x51
testing.(*common).Fatalf(0xc000248680, {0x93287f, 0x32}, {0x0, 0x0, 0x0})
        /usr/local/go/src/testing/testing.go:955 +0xaf
github.com/tikv/pd/pkg/gctuner.TestFinalizer.func1()
        /home/lhy1024/pd/pkg/gctuner/finalizer_test.go:35 +0x6f
github.com/tikv/pd/pkg/gctuner.finalizerHandler(0xc000216048)
        /home/lhy1024/pd/pkg/gctuner/finalizer.go:40 +0xc2
FAIL    github.com/tikv/pd/pkg/gctuner  2.954s

What version of PD are you using (pd-server -V)?

[lhy1024]

--- FAIL: TestTuner (0.39s)
    tuner_test.go:57: 
                Error Trace:    /home/lhy1024/pd/pkg/gctuner/tuner_test.go:57
                Error:          "296" is not less than or equal to "250"
                Test:           TestTuner
FAIL
coverage: 76.9% of statements
FAIL    github.com/tikv/pd/pkg/gctuner  3.353s

[lhy1024]

--- FAIL: TestGlobalMemoryTuner (2.20s)
    memory_limit_tuner_test.go:95: 
        	Error Trace:	/home/lhy1024/pd/pkg/gctuner/memory_limit_tuner_test.go:95
        	Error:      	Not equal: 
        	            	expected: 1181116006
        	            	actual  : 858993459
        	Test:       	TestGlobalMemoryTuner
    memory_limit_tuner_test.go:66: 
        	Error Trace:	/home/lhy1024/pd/pkg/gctuner/memory_limit_tuner_test.go:66
        	            				/home/lhy1024/pd/pkg/gctuner/panic.go:540
        	            				/home/lhy1024/pd/pkg/gctuner/testing.go:871
        	            				/home/lhy1024/pd/pkg/gctuner/memory_limit_tuner_test.go:95
        	Error:      	Not equal: 
        	            	expected: true
        	            	actual  : false
        	Test:       	TestGlobalMemoryTuner

[lhy1024]

--- FAIL: TestTuner (0.01s)
    tuner_test.go:40: 
        	Error Trace:	/home/lhy1024/pd/pkg/gctuner/tuner_test.go:40
        	Error:      	Not equal: 
        	            	expected: 0x1f4
        	            	actual  : 0x64
        	Test:       	TestTuner
FAIL

[lhy1024]

https://github.com/tikv/pd/actions/runs/4131564133/jobs/7139328066

[hnes]

The reason of "no cpu controller detected" error in TestGetCgroupCPU is because the kernel of the testing environment is too old and such old kernel is not supported very well by the current pkg/cgroup package. I think maybe this is not a very severe problem because we don't use GetCgroupCPU related functions currently.

[hnes]

In TiDB, these flaky tests in gctuner is marked as flaky and Bazel passes flaky tests if 1 out of 3 retries passes. There is also a tracking task list which aims to fix flaky tests and gctuner is one of them.