Repeated lockups with NFS home directory

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Repeated lockups with NFS home directory

Unread postby tim1mw » Wed, 21 Mar 2018, 16:34

Ever since the upgrade to 27.7.0, I've had repeated problems with PaleMoon locking up, sometimes every few minutes for periods lasting up to 30 seconds. Occasionally the lockups are fatal and I have to kill the browser. These problems have only affected my desktop system which uses NFS mounted home directories, my laptop does not and has no problems. Accessing ssl website and clicking on the bookmarks menu are particularly prone to trigger a freeze. The problem is sufficiently bad to make PaleMoon almost unusable at times, forcing me back to Firefox for many tasks.

I've tried everything to cure the problem, new profiles, removing addons etc. A few days ago I did some more searching and found that Firefox had a lot of trouble on systems with NFS home directories, which was primarily down to the use of SQLlite and it was recommended to use NSS_SDB_USE_CACHE=yes as an environment variable to fix this. I tried this for Pale Moon, but again no effect. As a last ditch attempt to fix the problem I tried moving the '.moonchild productions' directory off the NFS mounted drive onto a local partition (using a symlink on the NFS drive to point at it) and this has completely cured the problem. This is only a temporary solution, since it means that my PaleMoon profile is no longer being backed up.

So it seems that something in the 27.7.0 upgrade completely trashed performance of PaleMoon on NFS mounted drives. I note from the errata that SQLite was updated to 3.21.0, so I'm wondering if that version of SQLite has a major regression in NFS performance, or if there was a change in the way that PaleMoon uses SQLite as part of the upgrade. Is there any config setting I can use to fix the performance of PaleMoon on NFS, or am I stuck with this until the problem can be fixed in code? Has anybody else had this problem?

All comments and suggestions gratefully received.

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Re: Repeated lockups with NFS home directory

Unread postby New Tobin Paradigm » Wed, 21 Mar 2018, 17:18

Don't use a network for running profiles and application data.
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Re: Repeated lockups with NFS home directory

Unread postby tim1mw » Wed, 21 Mar 2018, 18:33

Why? everything else works just fine, Chrome has no trouble and Firefox fixed the issue they were having.

NFS homes directories are essential for my automatic backup and remote access, I've been running like this since 2001 and this is the first time I've had a problem. I used to work on the staff at the University of Birmingham, School of Computer Science, every single staff member and student has their home directory served via NFS to desktop systems, it's been that way there since the 1990's. If your attitude is that profiles shouldn't be on network drives then you've probably excluded many networked Linux/Unix shops as potential users of PaleMoon.

Sorry, but if the attitude is "don't use NFS", then my answer is that I'm not using PaleMoon, not using NFS is not an option. I had hoped for a more constructive answer to my first post here. Is there anybody else who would like to be constructive and help to solve the problem?
Last edited by tim1mw on Wed, 21 Mar 2018, 18:49, edited 6 times in total.

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Re: Repeated lockups with NFS home directory

Unread postby Walter Dnes » Thu, 22 Mar 2018, 05:19

Pale Moon (and Firefox) use SQLite. According to https://www.sqlite.org/faq.html#q5

SQLite uses reader/writer locks to control access to the database. (Under Win95/98/ME which lacks support for reader/writer locks, a probabilistic simulation is used instead.) But use caution: this locking mechanism might not work correctly if the database file is kept on an NFS filesystem. This is because fcntl() file locking is broken on many NFS implementations.

Can you check how well your nfs handles fcntl()?
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Re: Repeated lockups with NFS home directory

Unread postby Moonraker » Fri, 23 Mar 2018, 11:14

New Tobin Paradigm wrote:Don't use a network for running profiles and application data.

Sorry but that was a very useless reply and incredibly unconstructive.I think the original poster would of expected a more informative attempt at a solution rather than "dont use it.".
i assume customer service is not one of your strong points.
You will not attract new users with such a dismissive attitude.
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Re: Repeated lockups with NFS home directory

Unread postby New Tobin Paradigm » Fri, 23 Mar 2018, 15:10

It is common sense that a mozilla style application profile generally would not work as well under network filesystem conditions in general given disk cache, json, and sqlite storage.

Also, as Dnes actually correctly detailed, NFS its self can have its own major issues in general.

Additionally, and this is ONLY directed to Moonraker, you are not a customer, this is not a company and your assumption that user counts are top priority are flawed. I don't get paid to work here in fact last I checked I pay money out to help fund the project plus the countless unpaid manhours.

Regardless, if you are having a problem with my customer service, sir, you can always call 1-800-PISS-OFF because I don't have to do any of of the things I do and sure don't do them for the likes of you personally.
Last edited by New Tobin Paradigm on Fri, 23 Mar 2018, 15:18, edited 4 times in total.
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Re: Repeated lockups with NFS home directory

Unread postby Moonchild » Fri, 23 Mar 2018, 15:17

Stating a simple, direct recommendation is the correct response. Whether the technical details behind it are immediately stated or not doesn't take away from the usefulness of it.

Tobin, feel free to stop assisting users any time you please, because that kind of venomous attitude in response to your direct reply is certainly something *I* would consider reason enough to not help anymore.
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Re: Repeated lockups with NFS home directory

Unread postby Moonchild » Fri, 23 Mar 2018, 15:21

@tim1mw: the recommendation is indeed what Tobin said: Don't use NFS for live profile directories, or switch to a different implementation of NFS that doesn't choke up sqlite.
The fact that Firefox is less affected probably has something to do with Mozilla's ongoing JSON-ifying of everything, no matter the loss of performance involved.
Lacking an alternative NFS implementation on your system I'd suggest using a local shadow directory for your profile that you sync to your (NFS) home dir by stating the -profile CLI argument to Pale Moon to not directly use the home dir but the shadow instead.
Last edited by Moonchild on Fri, 23 Mar 2018, 15:24, edited 2 times in total.
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Re: Repeated lockups with NFS home directory

Unread postby daftman1 » Sat, 24 Mar 2018, 06:37

You could also use profile-sync-daemon to mount your profile dir in tmpfs and rsync the contents periodically and/or at logout/shutdown time back to the NFS.
It is normally used to save frequent writes on SSDs but from your description it could probably help in your case as well.

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Re: Repeated lockups with NFS home directory

Unread postby terranigma » Mon, 26 Mar 2018, 18:47

daftman1 wrote:You could also use profile-sync-daemon to mount your profile dir in tmpfs and rsync the contents periodically and/or at logout/shutdown time back to the NFS.
It is normally used to save frequent writes on SSDs but from your description it could probably help in your case as well.


An ext4 (or any other native linux FS) formatted image file can be used as a profile directory either. Loop device configurations will require root access anyway.

[1] https://wiki.archlinux.org/index.php/sparse_file
Last edited by terranigma on Mon, 26 Mar 2018, 18:49, edited 1 time in total.

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Re: Repeated lockups with NFS home directory

Unread postby tim1mw » Wed, 04 Apr 2018, 09:43

I'll admit to feeling hurt by Tobins response, I read between the lines that he was implying I was stupid to even consider using NFS homes (which are common practice where I have worked) so may not have been as polite as I should have been in my own reply. Perhaps that interpretation was wrong. However, I also believe that an answer which simply tells me not to do something without saying why I shouldn't do it is not an answer, eg he could have written this:

"Hi Tim, welcome to the forum. We don't currently support running Palemoon with NFS profiles because there are performance problems with some NFS implementations that can cause lockups".

Which says the same thing but also makes it clear that this isn't really Palemoons problem. I would have gone on to ask for more info on the NFS problem and we would come up with some ideas without the need for any unpleasantness. I appreciate that nobody here is paid to do this, I write and contribute to Opensource software as well and help others on forums such as this, as well as contributing in other ways without being paid.

I'll have a look at my NFS setup to see if fcntl() issues are causing a problem and can be fixed, that seems like the best approach. I'm not keen on shadow or synced profiles as a solution, but that's a personal preference, the suggestion is still appreciated and constructive and I may come back to it if there is not other way around this.

In my original post, I also mentioned how Firefox had fixed the problem through using the NSS_SDB_USE_CACHE=yes environment variable to switch on the caching behaviour of SQLite, which solves the problem. Is there any chance of a similar fix getting into Palemoon, does this already exist with a different name? If it's a case of "we simply don't want to do this", then that's perfectly fair, you're not obliged to support NFS homes.

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Re: Repeated lockups with NFS home directory

Unread postby Moonchild » Wed, 04 Apr 2018, 12:20

Hi Tim, Welcome to the forum. Don't use a network for running profiles and application data. *) **)

*) For technical details and reasons, use your knowledge of NFS or other networking file systems in general. If you currently lack this knowledge, educate yourself by performing several web searches and reading up on the inherent issues and drawbacks that may be involved.
**) This answer is purposefully generic due to the nature of people otherwise claiming BS reasons to diss our project for being too specific and it happening to be a different set of circumstances, which we can't possibly know, netting us with negativity anyway as well as wasted time and effort to provide a detailed answer that will likely be ignored anyway.
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Re: Repeated lockups with NFS home directory

Unread postby New Tobin Paradigm » Wed, 04 Apr 2018, 12:39

As a consolation prize I will be continuing to evaluate how my responses are phrased. Admittedly, I do fail on this sometimes..

However, do know that I tend to state exactly what I mean to say.. There is very little subtext if any with me. Implying implications isn't my go to first response to situations. I believe you read more into what I said than was intended. If you wanted clarification on the meaning of my words.. I would gladly explain what I mean in greater detail.

I am sorry if it affected you negatively because that was not my intention. As Moonchild states, these days it is more beneficial to offer a short and to the point answer then when requested or more likely pressed then go into greater detail. After years spent on this forum one fact is clear is that most people don't actually read what is said and even when they do they have no actual memory of doing so. It is a real problem because I have regularly gone into great detail on the forum only for people a few posts down to ask for the explanation again. Then someone else who didn't search the forum opens a new topic and it either gets linked to or restated again. And again.. And again..

I have a lot to do that things like this take time away from.. Right now, I am trying to port Pale Moon to the new Unified XUL Platform but instead of doing that this second.. I am writing this post.

If a drive by, correct, response can serve then it serves. If not then things can go into more detail by whomever responded first or someone else familiar with the issue at hand.

You have your answers and explanations way beyond NFS. Please try and have a good rest of your day.
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