memcached performance on Mac OS 10.4

[Noah M. Daniels]

Two simple changes:

First, in memcached.c (in the memcached source directory) add  
(anywhere above line 105, which reads #ifdef TCP_NOPUSH) the line:

  #undef TCP_NOPUSH

I just added it on the line above the #ifdef line.

Rebuild memcached (just do a make && sudo make install, don't need to  
re-run configure if you've already done it)

then, set the environment variable EVENT_NOKQUEUE to 1

in csh and derivatives: setenv EVENT_NOKQUEUE 1

in sh and derivatives (like bash): export EVENT_NOKQUEUE=1

then start memcached, and it should be fast (it certainly made a  
difference here)


On Mar 2, 2006, at 11:42 AM, Peter Bengtson wrote:

> Can somebody summarize, please?
>
> 	/ Peter Bengtson
>
>
> 2 mar 2006 kl. 17.39 skrev Brad Fitzpatrick:
>
>> On Thu, 2 Mar 2006, Noah M. Daniels wrote:
>>
>>> Ok, that makes more sense... so I disable both kqueue and NOPUSH.
>>> Does libevent need rebuilt with certain flags? Or will setting the
>>> EVENT_NOPOLL environment variable be sufficient?
>>
>> If anything you'd want EVENT_NOKQUEUE, if that exists.  Should  
>> work, if
>> so.
>>
>>>
>>>
>>> On Mar 2, 2006, at 11:31 AM, Brad Fitzpatrick wrote:
>>>
>>>> On Thu, 2 Mar 2006, Brad Fitzpatrick wrote:
>>>>
>>>>> If you rebuild libevent with kqueue support, and disable  
>>>>> TCP_NOPUSH
>>>>
>>>> _without_ kqueue support, sorry.
>>>>
>>>>> support in memcached (which it tries to auto-detect), then
>>>>> memcached will
>>>>> be fast on OS X, but you're limited in your number of concurrent
>>>>> connections.  Or rather, it'll eat more CPU as you have more  
>>>>> clients
>>>>> connected because it has to poll()/select().
>>>>>
>>>>> The problem, as I understand it, is:
>>>>>
>>>>>    kqueue is auto-detected, but sucks on OS X.
>>>>>
>>>>>    NOPUSH is auto-detected, but sucks (on OS X and FreeBSD?) or  
>>>>> its
>>>>>      semantics diff from TCP_CORK on Linux.  not quite sure.
>>>>>
>>>>> In any case, a coworker of mine using memcached on OS X (for
>>>>> development,
>>>>> not production), had success with the above.
>>>>>
>>>>> - Brad
>>>>>
>>>>>
>>>>> On Sun, 15 Jan 2006, Peter Bengtson wrote:
>>>>>
>>>>>> I'm experiencing the previously reported 200 ms latency on each
>>>>>> memcached query. As five queries per second is far, far worse  
>>>>>> than
>>>>>> scrapping memcache altogether and running without memory  
>>>>>> caching, I
>>>>>> was wondering if the problems on Mac OS 10.4 have been addressed
>>>>>> and/
>>>>>> or worked around in any way since Gregory Block wrote the  
>>>>>> following
>>>>>> to this list in March last year:
>>>>>>
>>>>>>> I had a bug open on Radar regarding memcached causing core dumps
>>>>>>> when
>>>>>>> used in poll(), kevent(), or anything other than select.   
>>>>>>> I've been
>>>>>>> informed by the team that there's a fix in place for Tiger, and
>>>>>>> that
>>>>>>> they've tested under tiger and poll() without seeing the kernel
>>>>>>> panics.
>>>>>>>
>>>>>>> So...
>>>>>>>
>>>>>>> Until that fix is in place, it's memcached + select() on mac os
>>>>>>> x, or
>>>>>>> watch your kernel go tits up.
>>>>>>
>>>>>> Of course, libevent since v1.1 has a "workaround", but  
>>>>>> memcache when
>>>>>> using libevent 1.1a and started in the following fashion:
>>>>>>
>>>>>> 	/usr/local/bin/memcached -k -uroot
>>>>>>
>>>>>> still reports:
>>>>>>
>>>>>> 	[warn] kq_init: detected broken kqueue; not using.: Bad file
>>>>>> descriptor
>>>>>>
>>>>>> and then proceeds to respond exactly five times a second.
>>>>>>
>>>>>> Also, James Robinson wrote, on Aug 30:
>>>>>>
>>>>>>> stores of payload between 14000 and 195846 bytes all happen  
>>>>>>> on OS X
>>>>>>> without delay. Apparently OS X's TCP_NOPUSH is just plain
>>>>>>> busted, as
>>>>>>> seems to be the net wisdom garnered from google.
>>>>>>
>>>>>> So, I'm wondering what is happening here. Are the Mac OS 10.4
>>>>>> implementations of kqueue and TCP_NOPUSH still broken? Are  
>>>>>> there any
>>>>>> patches from Apple or any third-party solutions? And is the slow
>>>>>> speed we're seeing the result of select() being inherently  
>>>>>> slow on
>>>>>> Mac OS X? Is there another way of forcing memcached use poll()?
>>>>>>
>>>>>> 	/ Peter Bengtson
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>
>>>
>