RegularExpression tests are failing in the CI builds

[jaredpar]

The tests look to be hanging / crashing. Here is the helix log

----- start Fri 24 Jan 2020 04:13:49 PM UTC =============== To repro directly: =====================================================
pushd .
/root/helix/work/correlation/dotnet exec --runtimeconfig System.Text.RegularExpressions.Tests.runtimeconfig.json --depsfile System.Text.RegularExpressions.Tests.deps.json xunit.console.dll System.Text.RegularExpressions.Tests.dll -xml testResults.xml -nologo -nocolor -notrait category=IgnoreForCI -notrait category=OuterLoop -notrait category=failing -notrait category=nonnetcoreapptests -notrait category=nonlinuxtests @mono.issues.rsp
popd
===========================================================================================================
/root/helix/work/workitem /root/helix/work/workitem
  Discovering: System.Text.RegularExpressions.Tests (method display = ClassAndMethod, method display options = None)
  Discovered:  System.Text.RegularExpressions.Tests (found 163 of 165 test cases)
  Starting:    System.Text.RegularExpressions.Tests (parallel test collections = on, max threads = 2)
   System.Text.RegularExpressions.Tests: [Long Running Test] 'System.Text.RegularExpressions.Tests.RegexCharacterSetTests.SetInclusionsExpected', Elapsed: 00:05:20
[Long Running Test] 'System.Text.RegularExpressions.Tests.RegexParserTests.Parse', Elapsed: 00:05:17
./RunTests.sh: line 161:    61 Killed                  "$RUNTIME_PATH/dotnet" exec --runtimeconfig System.Text.RegularExpressions.Tests.runtimeconfig.json --depsfile System.Text.RegularExpressions.Tests.deps.json xunit.console.dll System.Text.RegularExpressions.Tests.dll -xml testResults.xml -nologo -nocolor -notrait category=IgnoreForCI -notrait category=OuterLoop -notrait category=failing -notrait category=nonnetcoreapptests -notrait category=nonlinuxtests $RSP_FILE
/root/helix/work/workitem
----- end Fri 24 Jan 2020 04:23:55 PM UTC ----- exit code 137 ----------------------------------------------------------

Queues where the tests have failed:

• netcoreapp5.0-Linux-Release-x64-Mono_release-(Ubuntu.1910.Amd64.Open)ubuntu.1604.amd64.open
• netcoreapp5.0-Linux-Release-x64-CoreCLR_release-RedHat.7.Amd64.Open
• netcoreapp5.0-Linux-Release-x64-Mono_release-(Fedora.29.Amd64.Open)ubuntu.1604.amd64.open

Builds where the tests have failed;

• https://dev.azure.com/dnceng/public/_build/results?buildId=495817
• https://dev.azure.com/dnceng/public/_build/results?buildId=495434

[jaredpar]

FYI @stephentoub

[stephentoub]

Hmm, I'll take a look. Thanks.

[stephentoub]

ps Those tests are doing a lot of work. It's possible it's just too much for those machines.

[jaredpar]

@stephentoub FYI added one more failure queue to the list.

[stephentoub]

I see this in a failure on macOS on Mono:

dotnet: /__w/2/s/src/libraries/Native/Unix/System.Native/pal_time.c:165: int32_t SystemNative_GetCpuUtilization(ProcessCpuInformation *): Assertion `cpuUtilization >= 0 && cpuUtilization <= 100' failed.

[akoeplinger]

@stephentoub I've seen that in a couple of mono builds now but it's weird since that is in native code so shouldn't be mono-specific.

[stephentoub]

I've opened #2195 for the assert.

For this issue, I put up PR #2194 to address it. I'm pretty sure the test is just too expensive for CI; that one test class was doing ~58M regex matches, and I think the machines were just falling over (more frequently on mono, but the failures @jaredpar shared show it happening on coreclr as well).