- Glasgow-haskell-users

Fwd: Removing latency spikes. Garbage collector related?
by Will Sewell 29 Sep '15

29 Sep '15

Thanks for the reply Greg. I have already tried tweaking these values a bit, and this is what I found: * I first tried -A256k because the L2 cache is that size (Simon Marlow mentioned this can lead to good performance http://stackoverflow.com/a/3172704/1018290) * I then tried a value of -A2048k because he also said "using a very large young generation size might outweigh the cache benefits". I don't exactly know what he meant by "a very large young generation size", so I guessed at this value. Is it in the right ballpark? * With -H, I tried values of -H8m, -H32m, -H128m, -H512m, -H1024m But all lead to worse performance over the defaults (and -H didn't really have much affect at all). I will try your suggestion of setting -A to the L3 cache size. Are there any other values I should try setting these at? As for your final point, I have run space profiling, and it looks like >90% of the memory is used for our message index, which is a temporary store of messages that have gone through the system. These messages are stored in aligned chunks in memory that are merged together. I initially though this was causing the spikes, but they were still there even after I removed the component. I will try and run space profiling in the build with the message index. Thanks again. On 28 September 2015 at 19:02, Gregory Collins <greg(a)gregorycollins.net> wrote: > > On Mon, Sep 28, 2015 at 9:08 AM, Will Sewell <me(a)willsewell.com> wrote: >> >> If it is the GC, then is there anything that can be done about it? > > Increase value of -A (the default is too small) -- best value for this is L3 > cache size of the chip > Increase value of -H (total heap size) -- this will use more ram but you'll > run GC less often > This will sound flip, but: generate less garbage. Frequency of GC runs is > proportional to the amount of garbage being produced, so if you can lower > mutator allocation rate then you will also increase net productivity. > Built-up thunks can transparently hide a lot of allocation so fire up the > profiler and tighten those up (there's an 80-20 rule here). Reuse output > buffers if you aren't already, etc. > > G > > -- > Gregory Collins <greg(a)gregorycollins.net>

3 5

ANN: CfN for new Haskell Prime language committee
by Herbert Valerio Riedel 23 Sep '15

23 Sep '15

Dear Haskell Community, In short, it's time to assemble a new Haskell Prime language committee. Please refer to the CfN at https://mail.haskell.org/pipermail/haskell-prime/2015-September/003936.html for more details. Cheers, hvr -- PGP fingerprint: 427C B69A AC9D 00F2 A43C AF1C BA3C BA3F FE22 B574

1 0

HEADS UP: Need 7.10.3?
by Austin Seipp 17 Sep '15

17 Sep '15

Hi *, (This is an email primarily aimed at users reading this list and developers who have any interest). As some of you may know, there's currently a 7.10.3 milestone and status page on our wiki: https://ghc.haskell.org/trac/ghc/wiki/Status/GHC-7.10.3 The basic summary is best captured on the above page: "We have not yet decided when, or even whether, to release GHC 7.10.3. We will do so if (but only if!) we have documented cases of "show-stoppers" in 7.10.2. Namely, cases from users where - You are unable to use 7.10.2 because of some bug - There is no reasonable workaround, so you are truly stuck - We know how to fix it - The fix is not too disruptive; i.e. does not risk introducing a raft of new bugs" That is, we're currently not fully sold on the need for a release. However, the milestone and issue page serve as a useful guide, and also make it easier to keep track of smaller, point-release worthy issues. So in the wake of the 8.0 roadmap I just sent: If you *need* 7.10.3 because the 7.10.x series has a major regression or problem you can't work around, let us know! - Find or file a bug in Trac - Make sure it's highest priority - Assign it to the 7.10.3 milestone - Follow up on this email if possible, or edit it on the status page text above - it would be nice to get some public feedback in one place about what everyone needs. Currently we have two bugs on the listed page in the 'show stopper category', possibly the same bug, which is a deal-breaker for HERMIT I believe. Knowing of anything else would be very useful. Thanks all! -- Regards, Austin Seipp, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

3 2

Re: HEADS UP: Need 7.10.3?
by Ruben Moor 16 Sep '15

16 Sep '15

Hello, I want to support the case of a GHC 7.10.3 release. The show-stopper for our company in 7.10.2 consists of ticket #10726 https://ghc.haskell.org/trac/ghc/ticket/10726 and ticket #10795 https://ghc.haskell.org/trac/ghc/ticket/10795 I.e. I am not able to compile my code on MS Windows and reached a point where my workaround is exhausted (reducing overall file path length in the project dependency). Luckily the fix has already been implemented and merged (into the 7.10 branch and HEAD). Cf. this commit https://github.com/ghc/ghc/commit/296bc70b5ff6c853f2782e9ec5aa47a52110345e and this stack issue: https://github.com/commercialhaskell/stack/issues/795#issuecomment-140618684 Thanks! Ruben Moor

1 0

HEADS UP (devs, users): 8.0.1 Roadmap
by Austin Seipp 14 Sep '15

14 Sep '15

Hi *, I've returned from vacation, and last week Simon, Simon and I met up again after a long break, and talked a bit about the upcoming release. The good news is that it is going to be an exciting one! The flip side is, there's a lot of work to be done! The current plan we'd roughly like to follow is... - November: Fork the new `ghc-8.0` STABLE branch - At this point, `master` development will probably slow as we fix bugs. - This gives us 2 months or so until branch, from Today. - This is nice as the branch is close to the first RC. - December: First release candidate - Mid/late February: Final release. Here's our current feature roadmap (in basically the same place as all our previous pages): https://ghc.haskell.org/trac/ghc/wiki/Status/GHC-8.0.1 As time goes on, this page will be updated to reflect Reality™ and track it as closely as possible. So keep an eye on it! It's got the roadmap (near top) and large bug list (bottom). Now, there are some things we need, so depending on who you are, please... - *Users*: please look over the bug list! If there's a bug you need fixed that isn't there, set it to the 8.0.1 milestone (updated in Trac). If this bug is critical to you, please let us know! You can bump the priority (if we disagree, or it's workaround-able, it might get bumped down). We just need a way to see what you need, so please let us know somehow! As a reminder, our regular policy is this: if a bug is NOT marked highest or high priority, it is essentially 100% the case we will not look at it. So please make sure this is accurate. Or if you can, write a patch yourself! - *Developers*: double check the roadmap list, _and if you're responsible for something, make sure it is accurate!_ There are some great things planned to land in HEAD, but we'll have to work for it. Onward! - A better LLVM backend for Tier-1 platforms - Types are kinds and kind equality - Overloaded record fields! - Enhancements to DWARF debugging - ApplicativeDo - ... and many more... Thanks everyone! -- Regards, Austin Seipp, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

1 0

simultaneous ghc versions
by Evan Laforge 03 Aug '15

03 Aug '15

The recent release of ghc 7.10.2 reminded me of something I meant to ask about a long time ago. Most of the binaries ghc installs are versioned (x linked to x-7.10.2), with some exceptions (hpc and hsc2hs). Shouldn't they all be versioned? Also, 'haddock' is inconsistent with all the rest, in that it's haddock linked to haddock-ghc-7.10.2. I've long used a few shell scripts (recently upgraded to python) to manage ghc installs. A 'set' which creates symlinks to make a particular version current, and an 'rm' to remove all traces of a version. But due to the inconsistency, I have to remember to run "fix" first, which moves the unversioned binaries to versioned names. As an aside, I have three scripts I use all the time: set version, remove version, and remove library. Come to think of it, shouldn't ghc include this, instead of everyone creating their own shell scripts by hand?

9 12

Re: [Haskell-cafe] ANNOUNCE: GHC version 7.10.2
by Ben Gamari 30 Jul '15

30 Jul '15

James M <jmartin(a)eecs.berkeley.edu> writes: > There was talk from an earlier email thread of releasing the Haskell > Platform at the same time as 7.10.2. > > I am referring to the weekly news of 2015/05/11: > https://ghc.haskell.org/trac/ghc/blog/weekly20150511 > > and this email thread: > https://mail.haskell.org/pipermail/ghc-devs/2015-May/008911.html > > > Was this plan abandoned? Or was there something unexpected that is delaying > it? > Not at all! There ended up being a bit of timing skew between the Platform and GHC releases but an approximately concurrent release is still the plan. The Platform folks are hard at work as we speak, in the final stages of pushing out their release. I expect it will be announced shortly. Unfortunately due to the late notice of the text issue, the initial release will ship with text-1.2.1.1, which is still affected by the rewrite issue. That being said, the impact of this issue is mostly on compile time, in most cases you shouldn't see much impact on runtime performance. Moreover, they will be working to push out another release with text-1.2.1.3 in the coming days. Cheers, - Ben

1 0

Re: [Haskell-cafe] ANNOUNCE: GHC version 7.10.2
by Brandon Allbery 30 Jul '15

30 Jul '15

On Thu, Jul 30, 2015 at 12:52 PM, James M <jmartin(a)eecs.berkeley.edu> wrote: > There was talk from an earlier email thread of releasing the Haskell > Platform at the same time as 7.10.2. I think the right place to ask this is libraries(a)haskell.org. I would imagine they're in final testing and/or getting release packages in place. (Note as previously mentioned that "text" was just updated, and the Platform needs that; this presumably means they had to start over making release packages.) -- brandon s allbery kf8nh sine nomine associates allbery.b(a)gmail.com ballbery(a)sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

1 0

ANNOUNCE: GHC version 7.10.2
by Ben Gamari 30 Jul '15

30 Jul '15

===================================================================== The (Interactive) Glasgow Haskell Compiler -- version 7.10.2 ===================================================================== The GHC Team is pleased to announce a new bug-fix release of GHC, 7.10.2. There have been a number of significant bug fixes since the 7.10.1 (with over 70 defects fixed). These include fixes affecting type-checker correctness, runtime stability, and compiler performance. For this reason we highly recommend that users of 7.10.1 upgrade quickly. Note that due to changes made in this release to GHC's optimizer, previously fragile-but-working rewrite rules may fail to fire. One example of this was found in the widely-used `text` package late in the release cycle, which manifested in long compilation times and poor code generation for `Text` literals (see [Trac #10528]). Users are advised to use text >=1.2.1.2 which includes more robust rewrite rules. The full release notes including a complete listing of the changes in this release can be found here, https://downloads.haskell.org/~ghc/7.10.2/docs/html/users_guide/release-7-1… [Trac #10528]: https://ghc.haskell.org/trac/ghc/ticket/10528 How to get it ~~~~~~~~~~~~~ Both binary and source tarballs of GHC itself are available on the release download page, https://www.haskell.org/ghc/download_ghc_7_10_2 For a more smoother, better integrated experience users are encouraged to find a Haskell distribution. While these alternatives may not yet include 7.10.2, they offer tools and libraries to quickly get users up and running, as well as potentially better integration with the host operating system and package manager. See, https://www.haskell.org/downloads for more details. Background ~~~~~~~~~~ Haskell is a standard lazy functional programming language. GHC is a state-of-the-art programming suite for Haskell. Included is an optimising compiler generating good code for a variety of platforms, together with an interactive system for convenient, quick development. The distribution includes space and time profiling facilities, a large collection of libraries, and support for various language extensions, including concurrency, exceptions, and foreign language interfaces (C, whatever). GHC is distributed under a BSD-style open source license. A wide variety of Haskell related resources (tutorials, libraries, specifications, documentation, compilers, interpreters, references, contact information, links to research groups) are available from the Haskell home page (see below), https://www.haskell.org/ Supported Platforms ~~~~~~~~~~~~~~~~~~~ The list of platforms supported by GHC and the people responsible for them can be found here, https://ghc.haskell.org/trac/ghc/wiki/Platforms https://ghc.haskell.org/trac/ghc/wiki/CodeOwners Ports to other platforms are possible with varying degrees of difficulty. The Building Guide describes how to go about porting to a new platform: https://ghc.haskell.org/trac/ghc/wiki/Building Developers ~~~~~~~~~~ If you enjoy using GHC, you will likely also enjoy contributing to it! We are always looking for new contributors. Instructions on accessing our source code repository, and getting started with hacking on GHC, are available from the GHC developer site, https://ghc.haskell.org/trac/ghc/ Mailing lists ~~~~~~~~~~~~~ We run mailing lists for GHC users and bug reports; to subscribe, use the web interfaces at https://www.haskell.org/mailman/listinfo/glasgow-haskell-users https://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs There are several other haskell and ghc-related mailing lists on www.haskell.org; for the full list, see https://www.haskell.org/mailman/listinfo/ Some GHC developers hang out on #haskell on IRC, too: https://www.haskell.org/haskellwiki/IRC_channel Please report bugs using our bug tracking system. Instructions on reporting bugs can be found here: https://www.haskell.org/ghc/reportabug Hashes & Signatures ~~~~~~~~~~~~~~~~~ In https://downloads.haskell.org/~ghc/7.10.2/ you will find a signed copy of the SHA256 hashes for the tarballs, using my GPG key, Benjamin Gamari <ben(a)well-typed.com> Fingerprint: FFEB 7CE8 1E16 A36B 3E2D ED6F 2DE0 4D4E 97DB 64AD

6 9

broken source link
by Christian Maeder 24 Jul '15

24 Jul '15

Hi, when trying to look up the original definition for Data.List.transpose in https://downloads.haskell.org/~ghc/latest/docs/html/libraries/Data-List.html I found that the source link https://downloads.haskell.org/~ghc/latest/docs/html/libraries/src/Data-OldL… does not work. Could this be fixed? Or should I look elsewhere for the sources? Cheers Christian P.S. my looking up transpose was inspired by https://mail.haskell.org/pipermail/haskell-prime/2015-March/003933.html

2 1