[GHC] #14310: Assertion triggered by STM invariant.

[GHC]

#14310: Assertion triggered by STM invariant.
----------------------------------+--------------------------------------
        Reporter:  mbw            |                Owner:  (none)
            Type:  bug            |               Status:  new
        Priority:  high           |            Milestone:  8.4.1
       Component:  Compiler       |              Version:  8.2.1
      Resolution:                 |             Keywords:
Operating System:  Linux          |         Architecture:  x86_64 (amd64)
 Type of failure:  Runtime crash  |            Test Case:
      Blocked By:                 |             Blocking:
 Related Tickets:                 |  Differential Rev(s):
       Wiki Page:                 |
----------------------------------+--------------------------------------

Comment (by bgamari):

 Here is a representative snipped from the `+RTS -Dm` output of a run of
 the testcase,
 {{{
 ...
 7fcb1bfff700: STM: 0x42002fdea0 : stmCommitTransaction()=0
 7fcb1bfff700: STM: 0x505e28 : stmStartTransaction with 611 tokens
 7fcb1bfff700: STM: 0x505e28 : stmStartTransaction()=0x42002fdea0
 7fcb1bfff700: STM: 0x42002fdea0 : stmReadTVar(0x42002ff8f8)
 7fcb1bfff700: STM: 0x42002fdea0 : get_entry_for TVar 0x42002ff8f8
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=0
 7fcb1bfff700: STM: 0x42002fdea0 :
 read_current_value(0x42002ff8f8)=0x42002ff919
 7fcb1bfff700: STM: 0x42002fdea0 : stmReadTVar(0x42002ff8f8)=0x42002ff919
 7fcb1bfff700: STM: 0x42002fdea0 : stmReadTVar(0x42002ff938)
 7fcb1bfff700: STM: 0x42002fdea0 : get_entry_for TVar 0x42002ff938
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=1
 7fcb1bfff700: STM: 0x42002fdea0 :
 read_current_value(0x42002ff938)=0x42002ff95a
 7fcb1bfff700: STM: 0x42002fdea0 : stmReadTVar(0x42002ff938)=0x42002ff95a
 7fcb1bfff700: STM: 0x42002fdea0 : stmWriteTVar(0x42002ff8f8, 0x420002eee9)
 7fcb1bfff700: STM: 0x42002fdea0 : get_entry_for TVar 0x42002ff8f8
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=2
 7fcb1bfff700: STM: 0x42002fdea0 : stmWriteTVar done
 7fcb1bfff700: STM: 0x42002fdea0 : stmReadTVar(0x42002ff970)
 7fcb1bfff700: STM: 0x42002fdea0 : get_entry_for TVar 0x42002ff970
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=2
 7fcb1bfff700: STM: 0x42002fdea0 :
 read_current_value(0x42002ff970)=0x42002ff991
 7fcb1bfff700: STM: 0x42002fdea0 : stmReadTVar(0x42002ff970)=0x42002ff991
 7fcb1bfff700: STM: 0x42002fdea0 : stmWriteTVar(0x42002ff9b0, 0x420002efd2)
 7fcb1bfff700: STM: 0x42002fdea0 : get_entry_for TVar 0x42002ff9b0
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=3
 7fcb1bfff700: STM: 0x42002fdea0 :
 read_current_value(0x42002ff9b0)=0x4fe191
 7fcb1bfff700: STM: 0x42002fdea0 : stmWriteTVar done
 7fcb1bfff700: STM: 0x42002fdea0 : stmWriteTVar(0x42002ff970, 0x420002efe9)
 7fcb1bfff700: STM: 0x42002fdea0 : get_entry_for TVar 0x42002ff970
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=4
 7fcb1bfff700: STM: 0x42002fdea0 : stmWriteTVar done
 7fcb1bfff700: STM: 0x42002fdea0 : stmReadTVar(0x42002ff688)
 7fcb1bfff700: STM: 0x42002fdea0 : get_entry_for TVar 0x42002ff688
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=4
 7fcb1bfff700: STM: 0x42002fdea0 :
 read_current_value(0x42002ff688)=0x42002ff230
 7fcb1bfff700: STM: 0x42002fdea0 : stmReadTVar(0x42002ff688)=0x42002ff230
 7fcb1bfff700: STM: 0x42002fdea0 : stmWriteTVar(0x42002ff688, 0x420002a088)
 7fcb1bfff700: STM: 0x42002fdea0 : get_entry_for TVar 0x42002ff688
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=5
 7fcb1bfff700: STM: 0x42002fdea0 : stmWriteTVar done
 7fcb1bfff700: STM: 0x42002fdea0 : stmGetInvariantsToCheck, head was
 0x505e18
 7fcb1bfff700: STM: 0x42002fdea0 : lock_stm()
 7fcb1bfff700: STM: 0x42002fdea0 : lock_tvar(0x42002ff8f8)
 7fcb1bfff700: STM: 0x42002fdea0 : checking for invariants on 0x42002ff8f8
 7fcb1bfff700: STM: 0x42002fdea0 : unlock_tvar(0x42002ff8f8, 0x42002ff919)
 7fcb1bfff700: STM: 0x42002fdea0 : lock_tvar(0x42002ff970)
 7fcb1bfff700: STM: 0x42002fdea0 : checking for invariants on 0x42002ff970
 7fcb1bfff700: STM: 0x42002fdea0 : unlock_tvar(0x42002ff970, 0x42002ff991)
 7fcb1bfff700: STM: 0x42002fdea0 : lock_tvar(0x42002ff9b0)
 7fcb1bfff700: STM: 0x42002fdea0 : checking for invariants on 0x42002ff9b0
 7fcb1bfff700: STM: 0x42002fdea0 : unlock_tvar(0x42002ff9b0, 0x4fe191)
 7fcb1bfff700: STM: 0x42002fdea0 : lock_tvar(0x42002ff688)
 7fcb1bfff700: STM: 0x42002fdea0 : checking for invariants on 0x42002ff688
 7fcb1bfff700: STM: 0x42002fdea0 : Touching invariant 0x42002ffd50
 7fcb1bfff700: STM: 0x42002fdea0 : Not already found 0x42002ffd50
 7fcb1bfff700: STM: 0x42002fdea0 : unlock_tvar(0x42002ff688, 0x42002ff230)
 7fcb1bfff700: STM: 0x42002fdea0 : unlock_stm()
 7fcb1bfff700: STM: 0x42002fdea0 : stmGetInvariantsToCheck, head now
 0x420002c6d8
 7fcb1bfff700: STM: 0x42002fdea0 : stmStartTransaction with 610 tokens
 7fcb1bfff700: STM: 0x42002fdea0 : stmStartTransaction()=0x420002c6f8
 7fcb1bfff700: STM: 0x420002c6f8 : stmReadTVar(0x42002ff688)
 7fcb1bfff700: STM: 0x420002c6f8 : get_entry_for TVar 0x42002ff688
 7fcb1bfff700: STM: 0x420002c6f8 : FOR_EACH_ENTRY,
 current_chunk=0x420002c720 limit=0
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=5
 7fcb1bfff700: STM: 0x420002c6f8 : stmReadTVar(0x42002ff688)=0x420002a088
 7fcb1bfff700: STM: 0x420002c6f8 : stmAbortTransaction
 7fcb1bfff700: STM: 0x420002c6f8 : lock_stm()
 7fcb1bfff700: STM: 0x420002c6f8 : retaining read-set into parent
 0x42002fdea0
 7fcb1bfff700: STM: 0x420002c6f8 : FOR_EACH_ENTRY,
 current_chunk=0x420002c720 limit=1
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=5
 7fcb1bfff700: STM: 0x420002c6f8 : unlock_stm()
 7fcb1bfff700: STM: 0x420002c6f8 : stmAbortTransaction done
 7fcb1bfff700: STM: 0x42002fdea0 : stmCommitTransaction()
 7fcb1bfff700: STM: 0x42002fdea0 : lock_stm()
 7fcb1bfff700: STM: 0x42002fdea0 : locking invariants
 7fcb1bfff700: STM: 0x42002fdea0 : locking invariant 0x42002ffd50
 7fcb1bfff700: STM: 0x42002fdea0 : failed to lock 0x42002ffd50
 7fcb1bfff700: STM: 0x42002fdea0 : finished locking invariants
 7fcb1bfff700: STM: 0x42002fdea0 : FOR_EACH_ENTRY,
 current_chunk=0x42002ff3f8 limit=5
 7fcb1bfff700: STM: 0x42002fdea0 : unlock_stm()
 7fcb1bfff700: STM: 0x42002fdea0 : stmCommitTransaction()=0
 }}}
 AFAICT the log essentially consists of tens of thousands of repeats
 similar to this.

 The `failed to lock` line is quite intriguing;

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14310#comment:9>
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