ok, at long last it's back:

http://wiki.diyfaq.org.uk/index.php/Main_Page

We have migrated to the most recent version - so some things may look
subtly different - but it ought to be pretty much as it was. The same
extensions are there as before, so things like visual editing, and the
"math" library should still work.

A quick recap on events...

We initially pulled it down from the server it was running on, since
that was having problems serving the main site it was supposed to be
running... and the wiki seemed to be making it worse.

After much investigation it turns out that the likely root cause of the
problem is not actually the wiki as such, but a kernel memory leak on
the server. Basically in the three years it has been up, it was very
slowly gaining an ever larger pool of "unrecoverable" kernel memory, and
hence there was an ever decreasing pool available for applications - and
the wiki was pushing it over the edge - causing users of the main
application to get "500" errors at random times.

So anyway we have re-hosted the wiki and brought it up to the current
version of MediaWiki. That then opened a whole new can of worms. Part of
that process needs to run a maintenance process on the database to make
the required changes for compatibility for the new version, and that
process was failing.

Eventually we traced that down to some database corruption going right
back to the very early days of the wiki when it used to be writeable by
anyone even without an account. There was a time it got lots of spam and
vandalism, and at some point some of that spam content had been deleted
in a way that broke referential integrity of the database. Had you have
tried to follow an articles history to view one of the affected spammed
pages, you may have seen an error, but otherwise it just lurked there
dormant and waiting to bite :-)

There were about 80 missing records in one table. In the end we manually
recreated those one by one to patch up the gaps. (there may as a result
be some old vandalised pages that will not link to the expected content
if you wade though the article histories (they would have been broken
before - but now they are just broken differently!))

Then for one final kick, we spent a few hours wading through wireshark
logs to try and work out why the new setup was serving pages that looked
fine in Firefox, but were unreadable in Chrome or Edge. It seemed like
there was something broken with the on the fly compression that is
applied on page downloads not being reversed correctly at the browser.
That turned out to be a bug in MediaWiki 1.35.1 that they somehow
managed to let right the way through the release process and into a
"live" version! So we have knobbled the relevant bit of MediaWiki code
to fix that, rather than change the whole version again.




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:

ok, at long last it's back:

Thanks John, looks good

On 01/04/2021 15:29, Andy Burns wrote:
John Rumm wrote:

ok, at long last it's back:

Thanks John, looks good

+1

--

Jeff

On 01/04/2021 13:20, John Rumm wrote:


err...a simple "thanks" seems rather inadequate.

But if you fancy a wall Yosser Hughes would be proud of just point me to
it.



--
Robin
reply-to address is (intended to be) valid

On Thursday, 1 April 2021 at 13:20:25 UTC+1, John Rumm wrote:
ok, at long last it's back:

http://wiki.diyfaq.org.uk/index.php/Main_Page

We have migrated to the most recent version - so some things may look
subtly different - but it ought to be pretty much as it was. The same
extensions are there as before, so things like visual editing, and the
"math" library should still work.

A quick recap on events...

We initially pulled it down from the server it was running on, since
that was having problems serving the main site it was supposed to be
running... and the wiki seemed to be making it worse.

After much investigation it turns out that the likely root cause of the
problem is not actually the wiki as such, but a kernel memory leak on
the server. Basically in the three years it has been up, it was very
slowly gaining an ever larger pool of "unrecoverable" kernel memory, and
hence there was an ever decreasing pool available for applications - and
the wiki was pushing it over the edge - causing users of the main
application to get "500" errors at random times.

So anyway we have re-hosted the wiki and brought it up to the current
version of MediaWiki. That then opened a whole new can of worms. Part of
that process needs to run a maintenance process on the database to make
the required changes for compatibility for the new version, and that
process was failing.

Eventually we traced that down to some database corruption going right
back to the very early days of the wiki when it used to be writeable by
anyone even without an account. There was a time it got lots of spam and
vandalism, and at some point some of that spam content had been deleted
in a way that broke referential integrity of the database. Had you have
tried to follow an articles history to view one of the affected spammed
pages, you may have seen an error, but otherwise it just lurked there
dormant and waiting to bite :-)

There were about 80 missing records in one table. In the end we manually
recreated those one by one to patch up the gaps. (there may as a result
be some old vandalised pages that will not link to the expected content
if you wade though the article histories (they would have been broken
before - but now they are just broken differently!))

Then for one final kick, we spent a few hours wading through wireshark
logs to try and work out why the new setup was serving pages that looked
fine in Firefox, but were unreadable in Chrome or Edge. It seemed like
there was something broken with the on the fly compression that is
applied on page downloads not being reversed correctly at the browser.
That turned out to be a bug in MediaWiki 1.35.1 that they somehow
managed to let right the way through the release process and into a
"live" version! So we have knobbled the relevant bit of MediaWiki code
to fix that, rather than change the whole version again.




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/


Thanks John looks as good as it always was.

Richard

Andy Burns was thinking very hard :
John Rumm wrote:

ok, at long last it's back:

Thanks John, looks good

+1

On 01/04/2021 16:12, Robin wrote:
On 01/04/2021 13:20, John Rumm wrote:


err...a simple "thanks" seems rather inadequate.

But if you fancy a wall Yosser Hughes would be proud of just point me to
it.




I think Yosser rebuilt this one that I posted about a couple of years ago.

https://www.youtube.com/watch?v=1PCj...annel=ViralHog

I'll take a photo of the rebuilt wall next time I pass.

--
Adam

On 01/04/2021 13:20, John Rumm wrote:

ok, at long last it's back:

http://wiki.diyfaq.org.uk/index.php/Main_Page

Brill, I've missed it!

On 01/04/2021 19:28, ARW wrote:
On 01/04/2021 16:12, Robin wrote:
On 01/04/2021 13:20, John Rumm wrote:


err...a simple "thanks" seems rather inadequate.

But if you fancy a wall Yosser Hughes would be proud of just point me to
it.




I think Yosser rebuilt this one that I posted about a couple of years ago.

https://www.youtube.com/watch?v=1PCj...annel=ViralHog

I'll take a photo of the rebuilt wall next time I pass.

Did the car owner contact TNP? He seems to have a warehouse full of car
body filler based on the number of purposes he recommends it for,
although I'm not certain that even a jumbo-sized pack would be enough to
fix that wing!

--

Jeff