[GHC] #16349: Nondeterministic T3424 timeouts on CI

[GHC]

#16349: Nondeterministic T3424 timeouts on CI
-------------------------------------+-------------------------------------
           Reporter:  RyanGlScott    |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.9
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 The `T3424` test suite occasionally times out on CI, forcing me to restart
 builds to get a green build status. Here is [https://ghc-
 gitlab.s3.amazonaws.com/6b/86/6b86b273ff34fce19d6b804eff5a3f5747ada4eaa22f1d49c01e52ddb7875b4b/2019_02_21/31580/50071/job.log
 ?response-content-type=text/plain%3B%20charset%3Dutf-8&response-content-
 disposition=inline&X-Amz-Expires=600&X-Amz-Date=20190221T105115Z&X-Amz-
 Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAI3NPPHETCY4XXTOA/20190221
 /us-east-1/s3/aws4_request&X-Amz-SignedHeaders=host&X-Amz-
 Signature=521f4993a8af6215a34603cb8dfb26f10e3f2a335229227e65b92aa4ced557e9
 one example] from a `validate-x86_64-linux-deb9-unreg` run:

 {{{
 Timeout happened...killed process "cd "rts/T3424.run" &&
 "/builds/ghc/ghc/inplace/bin/ghc-stage2" -o T3424 T3424.hs -dcore-lint
 -dstg-lint -dcmm-lint -no-user-package-db -rtsopts -optc-fno-builtin -fno-
 warn-missed-specialisations -fshow-warning-groups -fdiagnostics-
 color=never -fno-diagnostics-show-caret -Werror=compat -dno-debug-output
 "...

 Compile failed (exit code 99) errors were:
 [1 of 1] Compiling Main             ( T3424.hs, T3424.o )

 *** unexpected failure for T3424(normal)

 <elided>

 Unexpected results from:
 TEST="T3424"

 SUMMARY for test run started at Thu Feb 21 05:18:04 2019 UTC
  1:15:50 spent to go through
     6839 total tests, which gave rise to
    21103 test cases, of which
    13986 were skipped

       38 had missing libraries
     6977 expected passes
      101 expected failures

        0 caused framework failures
        0 caused framework warnings
        0 unexpected passes
        1 unexpected failures
        0 unexpected stat failures

 Unexpected failures:
    rts/T3424.run  T3424 [exit code non-0] (normal)
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16349>
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