[GHC] #15010: Application (warp) server crashing periodically with "TSO object entered"

[GHC]

#15010: Application (warp) server crashing periodically with "TSO object entered"
-------------------------------------+-------------------------------------
           Reporter:  ramirez7       |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.4.3
          Component:  Runtime        |           Version:  8.0.2
  System                             |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Runtime crash
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 We are seeing one of our warp servers periodically crash with the
 following error:

 {{{
 Apr 06 10:44:28 stdouterr.log: binary-name-elided: internal error: TSO
 object entered!
 Apr 06 10:44:28 stdouterr.log:     (GHC version 8.0.2 for
 x86_64_unknown_linux)
 }}}

 We are sometimes seeing CPU/memory spikes concurrently with this error,
 but not always.

 We are running very similar servers for other applications and they are
 '''not''' experiencing this error. But this server is one of our highest-
 load ones.

 Other tickets I found with this error:
 * https://ghc.haskell.org/trac/ghc/ticket/12383
 * https://ghc.haskell.org/trac/ghc/ticket/8316

 But these seem to be happening in ghci and ghc itself, not in a binary
 compiled by ghc.

 Questions I have:
 * What exactly is this error?
 * Is there anything else we can do on our side to help debug? Any
 artifacts that should be produced upon crash?
 * Should we consider upgrading our GHC version from 8.0.2 to get a bugfix?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15010>
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