Looks like the memcached client devs were too lazy to add ASCII support to this on older versions. Seems to be fine in newer ones (http://php.net/manual/en/memcached.touch.php).

We can't just use BINARY because we use twemproxy, which is ASCII only.

@SBisson it is present in production if you use Zend. I tested with HHVM (which doesn't have the issue) earlier without considering this.

On Vagrant, we probably can just use BINARY though.

Change 306488 had a related patch set uploaded (by Mattflaschen):
Memcached PECL: Allow using binary protocol

https://gerrit.wikimedia.org/r/306488

Change 306490 had a related patch set uploaded (by Mattflaschen):
Use binary protocol with memcached

https://gerrit.wikimedia.org/r/306490

Change 306488 merged by jenkins-bot:
Memcached PECL: Allow using binary protocol

https://gerrit.wikimedia.org/r/306488

Change 306490 merged by jenkins-bot:
Use binary protocol with memcached

https://gerrit.wikimedia.org/r/306490

I've got the same issue running /srv/mediawiki/php-1.28.0-wmf.20/extensions/WikimediaMaintenance/createExtensionTables.php, see T127792#2690863.

There's a load of these on wikitech

mwdeploy@silver:/var/log/apache2$ grep -c "touch is only supported with binary protocol" error.log
1404
mwdeploy@silver:/var/log/apache2$ zgrep -c "touch is only supported with binary protocol" error.log.*
error.log.1:5161
error.log.10.gz:5166
error.log.11.gz:5450
error.log.12.gz:5526
error.log.13.gz:5356
error.log.14.gz:5271
error.log.15.gz:5106
error.log.16.gz:5141
error.log.17.gz:4902
error.log.18.gz:5408
error.log.19.gz:5346
error.log.20.gz:5157
error.log.21.gz:4761
error.log.22.gz:4883
error.log.23.gz:4990
error.log.24.gz:4711
error.log.25.gz:5623
error.log.26.gz:5538
error.log.27.gz:5114
error.log.28.gz:4655
error.log.29.gz:4758
error.log.2.gz:5211
error.log.30.gz:4753
error.log.3.gz:5234
error.log.4.gz:5401
error.log.5.gz:5202
error.log.6.gz:5190
error.log.7.gz:4968
error.log.8.gz:5024
error.log.9.gz:5048

Just so my last analysis from T158613#3218329 doesn't get lost, I'm reposting it here:

In T158613#3218262, @Andrew wrote:

So the reason this doesn't make MediaWiki hhvm-only is because normal non-WMF deploys of mediawiki don't include twemproxy?

• With php-memcached v2.1.0 (5 year old release we have on silver via Ubuntu 14.04 apt repos), the touch() action is restricted to binary only -- https://github.com/php-memcached-dev/php-memcached/blob/r2.1.0/php_memcached.c#L1406-L1410
• In php-memcached v2.2.0RC1 (4 years ago) they actually flipped this and warn if binary protocol is in use conditional on the libmemcached version -- https://github.com/php-memcached-dev/php-memcached/commit/79af37192618b81252d235b985f87f33f5e48669

So, any php-memcached released since 2014-03-12 should work fine with the current MediaWiki core code. We just happen to live in the dark ages due to silver being a Trusty host. Jessie ships php-memcached v2.2.0 which should support touch() via the ASCII protocol that we use.

$ php -v
PHP 5.6.30-0+deb8u1 (cli) (built: Feb  8 2017 08:50:21)
Copyright (c) 1997-2016 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend Technologies
    with Xdebug v2.2.5, Copyright (c) 2002-2014, by Derick Rethans
$ php --re memcached | head
Extension [ <persistent> extension #53 memcached version 2.2.0 ] {

  - INI {
    Entry [ memcached.sess_locking <ALL> ]
      Current = '1'
    }
    Entry [ memcached.sess_consistent_hash <ALL> ]
      Current = '0'
    }
    Entry [ memcached.sess_binary <ALL> ]
$ dpkg-installed | grep memcached
libmemcached11:amd64 1.0.18-4
libmemcachedutil2:amd64 1.0.18-4
memcached            1.4.21-1.1+deb8u1
php5-memcached       2.2.0-2

I thought we shut this error up at least. It's back on wmf.5

As I said on IRC: why do we even attempt this codepath when we're not in binary mode?

In T143464#3346719, @demon wrote:

As I said on IRC: why do we even attempt this codepath when we're not in binary mode?

We would have to check the php-memcached version too because in v2.2.0RC1 the behavior flips and binary mode raises the warning and text mode works. A better question if we are worried about compatibility might be why are we using touch() at all.

I mean the performance gain over a get/set is pretty obvious. But if we can support it reliably we might need some sort of fallback.

Change 379677 had a related patch set uploaded (by Chad; owner: Chad):
[mediawiki/core@master] Possibly re-attempt memcached touch when we've failed

https://gerrit.wikimedia.org/r/379677

Change 379677 abandoned by Chad:
Possibly re-attempt memcached touch when we've failed

Reason:
Meh

https://gerrit.wikimedia.org/r/379677

Looks like T186802 is another instance of this. I only noticed it recently but can't swear that it's new.