#14324: Consider deprecating STM invariant mechanism -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by bgamari: Old description:

fryguybob and I were recently discussing the STM invariant mechanism. This mechanism is, presumably, intended to expose problems from odd interleavings of transactions. However, fryguybob pointed out that the implementation currently takes so many locks that it very likely prevents these odd interleavings from occurring.

In addition, * the implementation doesn't handle nested STM invariants correctly (#7930) * the locking behavior of the implementation was, until very recently, utterly wrong (#14310) * the feature introduces quite a bit of complexity in the RTS * the interface has essentially no users, as evidenced by a Hackage search and the fact that #14310 went unnoticed for years

All of this raises the question: Is the STM invariants feature really where we want to spend our complexity budget? Perhaps it is time for this feature to quietly pass (after an appropriate deprecation period, of course).

New description: fryguybob and I were recently discussing the STM invariant mechanism (e.g. `Control.Monad.STM.check`). This mechanism is, presumably, intended to expose problems from odd interleavings of transactions. However, fryguybob pointed out that the implementation currently takes so many locks that it very likely prevents these odd interleavings from occurring. In addition, * the implementation doesn't handle nested STM invariants correctly (#7930) * the locking behavior of the implementation was, until very recently, utterly wrong (#14310) * the feature introduces quite a bit of complexity in the RTS * the interface has essentially no users, as evidenced by a Hackage search and the fact that #14310 went unnoticed for years All of this raises the question: Is the STM invariants feature really where we want to spend our complexity budget? Perhaps it is time for this feature to quietly pass (after an appropriate deprecation period, of course). -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14324#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14324: Consider deprecating STM invariant mechanism -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): I've opened a [[https://github.com/ghc-proposals/ghc-proposals/pull/77|GHC proposal]]. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14324#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14324: Consider deprecating STM invariant mechanism -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): The proposal has been [[https://github.com/ghc-proposals/ghc- proposals/blob/master/proposals/0011-deprecate-stm- invariants.rst|accepted]]. I will add the appropriate deprecation pragmas in `base-4.11.0.0` noting that removal will happen in three releases (presumably GHC 8.10). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14324#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14324: Consider deprecating STM invariant mechanism -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: closed Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.2.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4372 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: patch => closed * resolution: => fixed Comment: Merged in e5d0101121cf4ce4dffe59025360096ee57c5372. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14324#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14324: Consider deprecating STM invariant mechanism -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: GHCProposal Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #14310 | Differential Rev(s): Phab:D4372, Wiki Page: | Phab:D4760 -------------------------------------+------------------------------------- Changes (by bgamari): * status: closed => new * differential: Phab:D4372 => Phab:D4372, Phab:D4760 * resolution: fixed => * related: => #14310 Comment: We will follow-through with removal in 8.6.1. I've done this in Phab:D4760. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14324#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler